aj mccormack and son

Block Paving - Page 03
The Brew Cabin
block paving


spacer spacer spacer spacer spacer spacer
Forum Question 45 degree herringbone - D Feather
Tony, I posted an article some time ago on your site asking for advice about setting out this pattern. I have a big drive space, roughly 100msq, and it isn't a regular shape.

Well I have just finished laying all the blocks (Marshalls Ashbourne Red multi's) and I chose to run the pattern up from the driveway entrance. It looks great and I am chuffed to bits with it. I want to thank you and your site for all the advice and tips I have gained. This is my first time at this and I would be prepared to take anything on now.

Thanks once again, best wishes to you and your family.

forum answer Tony McCormack
I remember the problems and headaches it was giving you at the time. Great to hear you've got the drive you wanted and it's looking so good.

Send me a picture and I'll add it to the DIY Drives page.

Forum Question Is BP suitable for a very steep drive? - Portpatrick
I live in a house that is at the top of a very steep drive (about 45 degrees). The driveway was constructed 2 years ago and comprises of two rows of 3x2 concrete slabs layed end to end embedded in concrete. The slabs cover the route taken by the cars wheels and hardcore is positioned between and outside the slabs so that the width of the drive is about 8'. The ground is very rocky and drainage is not good, although rainwater seems to drain through the hardcore ok. The grass on either side of the drive can become very wet and soft during wet periods.

We dislike the look of the drive at the moment and would like to replace it with clay block paving that we think looks much more attractive. I however have 2 concerns:-

1.  Because of the steepness of the hill and because the cars enter the drive at an angle I am concerned that the block paving might 'move' given time. Is this likely? Could the whole area of paving be surrounded by concrete (as the 3x2s are at the moment) to prevent movement ? I have been looking around now for some considerable time and have never seen a drive as steep as ours with block paving.

2.  We live on the south west coast of Scotland where it rains a lot - especially during the winter months - and it can be damp. I understand the clay blocks can be affected by moss etc. moreso than the concrete blocks. I am concerned that due to the slope and poor drainage the water might drain 'down the hill' and over the blocks rather than between the blocks thus making the moss problem worse. Is this likely?

We really do like the look of the clay blocks, however if you feel they are unsuitable for our circumstances what surface would you recommend?

Thankyou for any assistance.


I've just realised that the steepness of the slope I quoted is wrong. The drive is approximately 24 metres long and in that distance drops about  5 - 6 metres, with the gradient at the bottom being slightly steeper at the bottom than at the top. So I suppose the gradient is about 1:4 at worst - nothing like 45 degrees! - but still quite steep.

forum answer Tony McCormack
Portpatrick asked...

Could the whole area of paving be surrounded by concrete (as the 3x2s are at the moment) to prevent movement?

The perimeter of a clay brick (or concrete block driveway should always be laid on and haunched with concrete. There are exceptions, but they are few and far between.

In your situation, I would insist on a firmly bedded and haunched edging course, particularly at the bottom and the sides.

I am concerned that due to the slope and poor drainage the water might drain 'down the hill' and over the blocks rather than between the blocks thus making the moss problem worse. Is this likely?

It's more than likely; it's absolutely certain!

Despite what seems to be a common misconception amongst members of the public, surface water does NOT drain through the joints of block paving. There's a study been done by the TRL (IIRC) and they calculate that 98% of the water that lands on a flexible block pavement will run-off - only 2% finds its way via the joints to the laying course and sub-base. Surface water does NOT drain through a block pavement. Some provision for collection and disposal of the SW must be made - gullies, linear drains and/or channels will be needed.

However, as you correctly state, clay pavers can be particularly prone to mosses, more so than concrete pavers, and not just the joints, but the surface of the pavers itself. Now, given the very steep nature of your driveway, this will be countered to some extent by the water cascading over the pavement during the  wet weather. Once the slope of a block/brick paved driveway gets above about 1:10, a sort of self-cleansing property becomes apparent, and mosses, algae and other vegetation find it hard to survive. That's not to say they find it impossible, just harder than it would be on, say, a 1:60 driveway.

This is easily remedied, though. Use of a quality urethane-based sealant will counter colonisation by mosses and other weeds, and, more importantly on your steep drive, will prevent the essential jointing sand being scoured out by the run off.

My opinion is that you should have no qualms about using clay pavers for your driveway. Laid properly, they will outlast us all, but I can't recommend too strongly the use of a quality, tested-and-approved sealant, not just to maintain its good looks, but to ensure its longer-term structural integrity.

One last point - you may want to consider using rigid construction for your driveway, rather than flexible. I can't say which is more appropriate without being familiar with the site, but it's certainly worth interrogating your contractors when you get them round to price up the job. A steep driveway in clays is a prime candidate for rigid work.

Portpatrick Thanks for such a prompt and informative reply. Your site is crammed full of useful information - especially for folk like me who do not have much of a clue.
Forum Question European fan pattern in clay cobbles - Teddington
Great site!! very helpful.

I am about to embark on laying my patio. Its 8m by 3m (24m^2 approx.) I wanted to use Marshals  56x56x60 clay cobble. Looking at your setting out Info for the fan it would mean using a 560mm radius. Is that right and will that look okay?

If yes do you have any tips and tricks, especially for setting out on site. I planed to have a border running the perimeter of the patio of 2 clay cobbles deep. This was to enclose the design. I realise that on the edge I will need to split the cobbles to fill the gaps, but within the complete fans do you need split cobbles?

I understand this is not the easiest pattern. I have laid simple blocks before but I think the fan design would look great.

Hope you can help.

forum answer Tony McCormack
It's a total doddle laying fans with the little clay cobbles, but use a 1120mm radius rather than 560mm, as a 560mm radius is too small to be noticed and will look 'bitty' on a patio.

In fact, you could probably get away with a 1m radius, giving you 3 full fans to one width of the patio, excluding the border edging. I have a drawing somewhere - give me a couple of hours to finish what I'm supposed to be doing and I'll see if I can find it and post it to this thread.

I have used a fan pattern with the clay cobbles on a number of occasions and they have to be the easiest paving unit to use with what is normally a complex pattern. You will need to split a few cobbles, but they are easily and accurately cracked with a lump hammer and bolster, and, because they have a raggedy-rusticky jagged edge anyway, you don't need to be exact. smile

For the border, I'd strongly recommend using a 200x100 clay paver. It forms a definite frame, rather than a bitty border, especially if a contrasting colour is used. There are some pix on the portfolio page that show the cobbles with a full-sized clay pavior as a border/soldier edging.

More later....

Images as promised....

This first one is a layout for a 560mm radius layout....

Fan layout

...while this second image is for a larger 870mm radius fan, which would give you 3 full fans across the patio, assuming a 200mm wide soldier course at the perimeter.

larger fan

Any help?

I'd definitely use the larger fan. The 560mm radius will look too small and will lose itself. The fans need to be large enough to impress upon the eye, but not so big that you have to stand at the top of the next street to understand the layout. The ideal fan size for a patio project is usually between 900mm and 1500mm radius.

Teddington Thank you very much for your time and trouble. Once I have drawn out my deign I would like to send it to you so that you could see if it was viable! I am not sure if I should use ordinary cobbles or Tumbled cobbles. Which do you prefer or is it just a matter of individual taste? Colour!! we have a red brick house initial thoughts were for a red/brown cobble but now I have seen blue/grey I quite like. Does it look okay to mix red and blue?

Thanks again for you rapid help

Tony McCormack Tumbled cobbles? Do you mean the Tegula Cobbles from Marshalls? They are somewhat bigger than the little clay cobbles - 80x80, IIRC. They look great as fans, but the colour isn't as strong as the clays.

The teg cobbles are quite subtle and don't look as natural as clay cobbles, but then, they don't get colonised by mosses quite as quickly as do the clays.

I'd make my choice depending on the look I was trying to achieve - rustic and lived in, definitely the clays: clean, up-to-date but traditional, the Teg Cobbles. Cost wise, I don't think there's more than coppers difference between the two.

Have you seen either of these products "in real life" or have you only seen publicity shots in the catalogues?

Teddington |I have only seen them on your site.
The tumbled cobbles were from Baggeridge Brick plc.
But you are right we will hve to see actual samples before we decide.
The idea of the fan again came from your site. I feel the only problem is seeing a sample will be difficult to imagine the finished design in our garden.
Tony McCormack Aaaah! I know the ones you mean - they come in 3 sizes, 50x50, 75x75 and 100x100. I designed a job using the 100x100s in a fan pattern last year.

If you contact Baggeridge they'll tell you where you can see the cobbles 'in situ'. They keep a list of projects where their products have been used. Try to view a job that's at least 12 months old, preferably 2 years or more, as the character 'mellows' with time as dust and detritus become ingrained and make the units look much more 'lived-in', IYKWIM.

Teddington We have now decided on using Marshalls Clay Cobbles, (56x56x60) and I think the Multi red colour. However I have just been looking at the price and I can not belive how expensive they are!! £620 for 11.2m². That is 3 times more expensive than block pavers (200x100mm) and over twice as expensive as good quality slabs!!!
Am I right or have I mis-calculated? I was very suprised.
Tony McCormack That's a bit on the expensive side, but that might be because you only need a relatively small quantity. Try shopping around, and don't rely on just one price, especially if it's from Travis Bloody Perkins.

It's worth asking a local paving contractor for a price, as I know a client that has bought them for less than 30 quid per m² in the last 12 months. They might be able to get you a keener price by adding whatever you need to a local order.

Teddington Was that £30 plus VAT ????

The prices I have been quoted is 12p to 16p per cobble plus VAT. I only need 15m² so i suppose that is a realativly low order. The prices were form Builder Centre

Tony McCormack 24 quid plus VAT = £28.20 per m²

That was for delivery to Sheffield (from Accrington, where they are made) and was for 112m², IIRC. I'm pretty sure they were bought through a local BM not[ one of the nationals such as TP or Builder Center(sic)

I'll see if I can get hold of the contractor tomorrow and find out just who they went through, if you'll pardon the expression. smile

Teddington Down to basics!!

I am sure it is on your site but.....

I have 15m² of old concrete patio. This is broken out. there is some existing sub grade material so i am putting down Type 1 to a depth of around 75mm. then a bed of sand to about 50mm. the bedding sand will be about 53mm below the edge course so that the 56x56x60mm clay cobbles will be 7mm proud this will be taken down by using a rubber backed wacker plate. Therefore, how much sand and Type 1 do I need?? I thought 2T of Type 1 and 1T of bedding sand. Is 1T what is delivered in those material bags? I ask all these questions because I am not sure if clay cobbles have a different procedure than claypavs.

Thank you again for being so helpful

Tony McCormack 2T of DTp1 should just about be enough. Depending on how accurate these Agg Bag tonnes are (some are sold by volume rather than weight) and the moisture content/rock type, I calculate you need around 2.1 Tonnes.

However, 1 Tonne of bedding sand won't be enough for 15m². You need nearer 1.5 tonnes, again depending on moisture content, which means buying 2 agg bags full. Given that you are tight with the sub-base material, you really can't afford to run short of bedding. Get 2 T of sand - the surplus can always be used for making haunching concrete or even added to the garden to improve a clay soil. smile

Teddington I have now finished the garden and would just like to say thank you very much for all your very helpful advice. It all worked very well and I am very keen now to do the front. I have emailed you some photos as it must be nice to realise that you really do make a difference.

Thanks again and I will be back.

Tony McCormack Your pictures do you enormous credit and they shall be appearing on the DIY Paving Page in the next few days.

Congratulations on such a great job!

Forum Question Random Patterns - Bee
Hi there fellow Forumites, my first time so please bear with me

Please can anybody advise me how to achieve a random pattern in a narrow space?

I live in a small, stone backtoback terrace with only 1350mm between the house and the original, low stone wall. (I have just fenced in front of the wall.) To complicate matters further I live on a steep hill, so will have to step the patio by breaking it into lengths of 2300mm and 3070mm, with a pathway between which is 1210mm by 1600mm (as obviously no wall there).

At the side of the house it steps up again and is 3200mm long, going from 1600mm wide (where the wall stops) back to 2440mm wide - I have decked the car sized space behind it to overcome the levels problem and finished it off at an angle to give a bit of interest.

So my space is 9780mm long in total, and ranging from 1350mm to 2440mm wide.

I am on quite a tight budget but would like to do something in keeping with the stone of the house; I have painted the decking a dull (wishy-washy!) green and the fence ?Acorn Brown? so was thinking of something like the Marshalls Heritage Old Yorkstone or Calder Brown, but have spent hours on Visio and still don't have a pattern that fits.

To make matters even worse, I am trying to establish the reason for a damp cellar - at it's worst it has about an inch of water on the floor and it has damp walls. I had a guy round who put dye in the drains but couldn't find any leaks, so I've just lived with it, but I figure I should sort it out before laying a patio. The two small areas in front of the house are currently deep earth, with about 6 inches of gravel on top (don't blame me, previous owners!). Originally I think there would have been below street-level windows. I know the house had a chemical DPC thingy done before I moved in but so far I have cleared the gravel and can't find the holes - I can't see them from inside the cellar too. Should I persevere and dig up a couple of feet of earth to look for the source? What then? Can I re-fill? How do I ensure adequate drainage? (Most houses in the street have above pavement-level flags or concrete.)

Oh it's all too much for a helpless female! wink

Thanks in anticipation for all your help and suggestions.

forum answer Tony McCormack
Hi Bee,

Firstly, it's possible to create a random layout in such a narrow space, if you choose the right flags. I could do you a custom design, for a nominal fee - smile

Alternatively, you are best using a CAD system, drawing the components to scale, and then playing about with them in a scaled drawing of the patio/path area. much as described on the Random Layouts page.

If your budget will stretch to it, have a look at Marshalls Chancery range. They are much more authentic looking, compared to their Heritage paving. Or you might like the Millstone from Stonemarket or even the Old Town from Bradstone.
Further, given you've such a tight area, I'd have a look at using something like the Tegula block pavings. Because they are relatively small units, they have the effect of making small spaces look bigger than they actually are, and a transverse (running across) pattern would prevent it all looking terribly narrow.

There's not much of a price difference between high-quality patio flags and tumbled blocks when used on an area such as this, and the Tegs are much easier for a DIY'er to lay.

Secondly, your damp problem. If you are re-paving the likely leak area, it's worth pricing up a drainage composite, such as Terram 1BZ, which can be laid horizontally, beneath the new paving to prevent any surface water finding its way through the paving and into your cellar. However, you may well find that it's groundwater from elsewhere that's penetrating the walls, and so a vertical drainage composite or impermemable membrane might be a better option.

Have you done any trial holes?

Bee Hi Tony

Thanks for your reply.

I do like the look of the Tegula blocks and thought they would be a good idea, but am (pleasantly) surprised you think they are easier for DIYers.

I'm going to visit a merchants and do a "touchy feely" test on some alternatives, as brochures only help so much. I also want to check the colours out.

My yard is currently lacking variety in shapes and heights - I have seen the info on Fan patterns and think this would look great in front of the decking, sort of disappearing under it. With 3200mm wide I think I could manage something.

(Hell I'm getting too ambitious I think! Before you know it I'll be building a Pergola for height.)

I will educate myself regarding the damp problem, using your comments as a starter for ten.

I guess that I could do some trial holes if I knew what and where I should be doing!

Tony McCormack It's tricky choosing from what you see at a Merchants yard, as you can't really judge what the blocks look like once they're laid and have been in place for a few months. My dad was saying yesterday that, if you had to choose a block paving from a single brick sample, you'd never choose the Tegula as it looks rough and dusty and knackered, but once it's laid, and the rain has washed off the dust, it's one of my favourite blocks.

If you contact Marshalls, they'll tell you where you can see it locally in situ, as it were, which is a much better way to choose.

For a fan pattern, you really need a minimum area of approx 5m x 3m. Anything less looks unfinished, unless you use under-sized fans, and then the whole job looks bitty. The trick with small spaces is not to try and dop too much. Keep it simple and it makes the space look bigger than it actually is.

Trial holes - basically, as small a hole as you can manage going down tight against the wall(s) with the damp problem. You're looking for owt obvious, like crumbling or rotten brickwork, open joints, fissures or cracks etc, or any standing water. It's one of those tasks that is best judged by someone with lots of experience, I'm afraid, but you might see something. At least it costs nowt! smile

Bee Good Afternoon Tony,

This has now turned more into a Damp/drainage issue than a Paving issue, although hopefully it will progress to the latter again soon!

Now I've cleared the cellar out I've found the holes from the Damp Course Injections, and they are thankfully above ground level.

I've dug down the area outside where the cellar wall is dampest (it's currently damp to the touch and eye). The area round where a window has been blocked up is dry to touch, the soil around it looks quite dry too - this is exactly where the vent from the gas boiler is situated.

However close to that is a drain, as it's the kitchen wall, and the soil there is very wet. I daren't dig much more as there's gas pipes and all sorts around there! Do you recommend I get a professional to take a look (again)?

One more thing I wonder if you could advise me on? I have dug out the paperwork from when I bought the house in 1992, as I remembered I was assigned the guarantee for the DPC. Between it being done in 1984 and me buying the house, the contractor ceased trading, but the guarantees were assigned to another contractor. (What a coincidence though, both the Director and Company Secretary have exactly the same names in both companies) smile

The original document mentions a 30 year guarantee, but surprise surprise I can't find the second company anywhere! Any ideas how I might find them, if they are operating under yet another name?

Just another thing I have realised, the person I bought the house from had the second company round in 1990 to check something out - I have a report saying they were satisfied the "moisture levels at ground floor level were minimal and related to condensation only". Now I'm wondering what prompted this inspection, as I've never had damp ABOVE ground level!

More or less settled on the Tegula BTW smile

Tony McCormack Hi Bee,

with regard to the damp, is there any chance it could be the drain you mention that is leaking? If you add a drain-tracing dye to whatever empties into that drain, it would show up in the ground water if there was a problem with the pipework, such as a leaky collar, or a cracked pipe.

Tracing the old dpc company - they are/were notorious for allegedly going bust shortly after making a huge wedge of money, much like some of the PIC Contractors we have nowadays. Companies House is your best bet in tracking them down.

If the drain is definitely above suspicion, then it might be worth getting a "no-obligation" damp survey done and see if that turns up anything.

I'm sure you'll enjoy the Tegula - let me know how it goes.

Forum Question Paving against DPC - Dave
I am currently having concrete block paving laid by a professional paving firm (Oyster Paving of Reading).

The edge course has been laid. The paving slopes across the front of the house. At one side it is two courses below the DPC, but at the other edge it is only 1/2 course. The blocks are flush to the front house wall. Is this acceptable?

I thought that paving should always be at least 2 courses below, but as this is a paving company I would hope that they know what they are doing.

forum answer Tony McCormack
It should be at least 150mm (2 courses of brick) below dpc, but there may be extenuating circumstances. Have you asked them why they've done it that way?
Dave Thank you for your reply.
No, I only noticed on my way out to work this morning.
Problem is, they could give some reason and I don't know enough to know if it is valid. Site is pretty level.
It was not mentioned before, in fact they were talking about installing a soakaway, but were going to wait until they had got all the levels before finally deciding on the best way to drain the drive. They haven't dug a soakaway yet.
Tony McCormack Ask them for an explanation and, if you think it has a definite whiff of bovine manure about it, tell me what they said and I'll tell you how plausible it is.
Dave Tony,

Thank you very much for taking the time to reply. Your help is greatly appreciated. Your site is probably the most informative and useful I have come across.
Their explanation is that in order to get the levels to match in with existing path (at the low end of the new drive), plus other suitable slopes to road and garden, they needed to rise this corner. The drive slopes both across the front of the house and away from the house at this point. They claim that by having this slope across the front (2 courses in about 30 ft) water will not collect and hence no damp.
Sounds reasonable to me (and the work they have done looks good), but I am still a bit concerned.
I thought one of the reasons for having drives 2 courses below DPC was to stop damp caused by rain splashing up from the path onto the brick work, or is this and old wives tale?

They state that, if I want, they will move back the drive edge from the house by the width of one block and infill with gravel, should I go for this (it won't look so good, but if it stops damp?)?

Thank you,

Tony McCormack The 150mm below dpc rule is, as you rcorrectly state, to prevent or minimise damp problem from splashback, and although the gradient they've created will not allow water to hang in that area, the fact that they're what? only 30-40mm below dpc is worrying and not something I would accept and certainly not something that would be permitted on a commercial or civil contract.

The gravel strip is, to my mind, a cheap cop out and again, I wouldn't be happy with it. You're paying for block paving, not bloody gravel!

I'm not familiar with the layout at your property, but the correct procedure when there's insufficient fall to drain an area of paving is to create a low point and add an extra gully, NOT elevate the paving up towards the dpc. How feasible this would be on your project, I can't say.

At the end of the day, it's your paving and you have to live with it. If you're happy, then fair enough, but, you must bear in mind that any encroachment of the '150mm below dpc' standard is the sort of thing a surveyor picks up on if you come to sell the property and then you're left with the choice of reducing your asking price or paying for remedial work.

My question to them would be why they haven't created a low point and installed an extra gully. This should have been allowed for in their original survey and pricing of the work.

Forum Question Contractors - Guy - 18 April 2002
Have not had much success in finding a contractor to pave my rear garden. Surface area approx 16 square metres and would like a light coloured block. One contractor offered massive cost for (basic/cheap) slabs and two more failed to arrive depite staying at home for the meetings. Any help would be very much appreciated. Thank you.
forum answer Tony McCormack - 18 April 2002
16m² isn't much of an enticement to many contractors, I'm afraid, Guy. I don't know too many contractors down there in London Village, but those I do have contact with tell me they are rushed off their feet at the moment and are only looking at 'prestige' jobs, by which they mean larger contracts or those that will get them noticed.

Maybe someone else reading this forum will be able to suggest a good contractor. Is it North London where you live, or are you south of that little stream that runs through the middle of the village? wink

18 April 2002
Explains why the contractors never turned up! Looks like a DIY job using slabs rather than blocks, how long should I assign to get the job done, a weekend? Can you reccommend any decent light coloured slabs???

Many thanks yet again...I think my last reply missed the correct thread and was mailed by mistake...

Tony McCormack
18 April 2002
If you're not mad keen on the DIY, you'll probably find block laying is a damn sight easier than flagging (or 'slabbing' as it's called in the south). I know from the feedback I get from other DIYers that they tend to enjoy the block laying, but flagging sends them mad, trying to get the bedding just right.

As for light coloured flags - depends what you're looking for. Something simple? Summat textured? Olde Worlde riven? Funky and contemporary? There are so many to choose from - I started building a 'gallery' of all the different types of blocks and patio flags about 6 weeks ago and it's still nowhere near finished!

Best suggestion is to get yourself a few catalogues. The Marshalls and Bradstone offerings are essential reading (although the Marshalls 2002 is so arty-farty, it's hard to judge the actual paving!) as they cover the widest ranges, but there's some really good products from companies such as Stonemarket, Bowland, Atlas, Charcon etc.

Tell me more about how you envisage the patio, and I'll see if I can suggest a few 'candidates'.

18 April 2002
Looks like 'Destroy It Yourself' may well be the route to completion and I take your advice for the block over flag issue.

So, assuming a 'block' finish is required, rather than flag, and the blocks should be light in colour and suitable for a North facing garden... what types might you recommend from your magnificent database?!I think at this stage a simple design would be best so blocks all round please!

Tony McCormack
18 April 2002
Olde worlde or modern? And what coloour is the house brick or dominant colour of the walls? Have you got a piccy?
19 April 2002
Many thanks again for your assistance. I have despatched a mail inculding a picture as requested.
Forum Question Ups and downs of BP - Loki - 19 April 2002
Hi Tony
I have to block pave a drive that is 70 ft long and 20 ft wide I have the digger digging it down to 10inches as I write this however i am a little concerned as to getting the levels right with the mot and sharp sand because the drive is like a big bowl , it falls down from the pavement by about 3 ft over the first 15 ft then it runs flat and goes back up by 3 ft for the last 15 ft to meet the rear garden so my levels are set by the pavement and the rear garden whats more the drive runs at the side of the house and the entrance to the house is mid way along the drive so my levels are set there by the dpc and the door so i will have to stay with the bowl effect with the new drive i was thinking of using marked pegs to know exactly how much mot is going where, and am i wondering about any tips u may have for me when doing this this type of drive thx m8y smile
forum answer Tony McCormack - 19 April 2002
The easiest method of checking both depth and excavation and the level of the sub-base material is to use a set of boning rods.

Set up a back sight at, say 1200mm above dpc on the corner of the house, then position a 1200mm fore sight on the public footpath, propped up with bricks or fixed to a footplate. Then, using a traveller set to (1200+100=1300mm) you can check the level of the top of the sub-base by sighting through, positioning the traveller anywhere you like between fore- and back sights.

You can repeat this for the back section, setting a fore sight at the garden and a back sight at the house.

If you want to form a hog-back curve in the profile, then have a look at the Profiling Kerblines[ page for further guidance.

Once the sub-base in laid, I prefer to lay my edging courses next, on a cement-bound bed and then use them as screed guides for the rest of the paving. That way. I can play about tweaking the profiling to achieve the sweet curves I prefer, and if necssary, the sub-base can then be checked again by stretching a string line from edging to edging course and 'dipping' to check, adding or taking away from the sub-base as required. Remember, a sub-base can be +/-10mm, but the more accurate you are, the less likely is the incidence of differential settlement in later years.

If you're not familiar with these terms, just let me know. I'm guessing you're a Contractor and will be familiar with boning rods, diff. settlement  and hog curves, but if it's all Greek to you, post back and I'll explain it all in Layman's terms. smile

21 April 2002
thx tony for the answer its nice to get a bit of reasurance from an expert such as yourself, we have a laser level which i will hopefully be able to implement in this job as well

thx again.

Forum Question Hardcore - Scud1365uk - 26 April 2002
I have broken up an old concrete path prior to replacing with block paving. I have kept much of it to use as hardcore but some peices are rather large(it was 18 inches thick in places). Is there a maximum size for chunks of hardcore or is it a case of if it fits in the hole use it? ........Thanks
forum answer Tony McCormack - 27 April 2002
Ideally, it should all be broken up so that no lumps are bigger than 50-60mm. If you have lots of big lumps, you can end up with significant differential settlement within the sub-base, which is then reflected in the paving.

To put that in layman's terms, the smaller bits in the sub-base may settle by, say, 10%, but the big lumps will not settle, or will settle only, say, 3%, so that what was a level sub-base soon becomes an uneven sub-base, and this difference in settlement is carried through to your paving, turning a level pavement into an uneven surface.

If you're intent on using the old concrete as a fill/sub-base, it's really worth the extra effort of breaking it up properly, with a sledgehammer, if necessary and getting a good, even sub-base. The analogy I always use is that of an underlay beneath a carpet - it doesn't matter how much you spend on the carpet and how well it is laid, if the underlay is crap, the final carpetting will be crap too.

Forum Question Like a fool... - Guy - 30 April 2002
Many thanks for your recent recomendation for my patio (the Marshalls Tegula Drivesett) and a fine choice it is. Your initial reply to my question regarding referral was negative due to the small size of the patio (16SqM). Like a fool I got my AutoCad clicks wrong and the area is more like 40SqM - would this be a more suitable size? Many thanks again for all your help.


forum answer Tony McCormack - 30 April 2002
That'll teach you to fool around with AutoCad! wink

40 m² would certainly be more appealling to a Contractor than 16m², but it's still on the small side. Were you looking for a Contractor?

01 May 2002
Yes please! I was looking to DIY at first but only because contrating might have been problematic. If you could advise on a contarctor (or two) it would be most useful. I live in Clapham parish.

Thanks as always...

Tony McCormack
01 May 2002
The following are Interlay members. I don't know any of them personally, but, as a rule, Interlay members are among the best contractors in the country.....

Eurobright Construction Ltd.
36 Gresham Road, Custom House, LONDON. E16 3DU
Tel: 020 7473 5491
Fax: 020 7473 5491

MJB Contracts Ltd.
Sinclair House, The Avenue, West Ealing, LONDON. W13 8NT
Tel: 020 8842 0043
Fax: 020 8842 0043

Tarmac Situsec
40-45 Herringham Road, Charlton, LONDON. SE7 8SJ
Tel: 020 8858 9409
Fax: 020 8305 2002

....or you could try the Marshalls' Register on their website - type in your postcode and it will give you a listing of your nearest Marshalls' approved contractors.

You should still get at least 2 quotes, just to be sure you're getting a fair price for your area.

Let me know how you get on.

Forum Question Existing base for block paving - NoviceJohn - 03 May 2002
Hi Tony,

you may recall helping out on my cracked concrete drive question a few days ago. on a related topic i had originally had in mind to lay classico bricks on a small section outside the kitchen door by removing the concrete base in the same manner as i originally planned for the drive i.e using the angle grinder to cut the segment shape out of the concrete and replacing with the blocks. i now know this is not a good idea!

as i have now put the driveway (which encompasses the area near the kitchen door ) on hold until i can renew the lot i wondered if it might be feasible to still put down the blocks (albeit temporary) using the concrete as a base?. on renewal of the driveway i would then set them correctly on the right sub-base.

i am looking to do an arc to form a sector of approx. 3 metres, would keep a 'gulley' next to the house for drainage and away from damp proof course and effectively have a raised area to the depth of the blocks.
i would retain the blocks in an outer line of slightly deeper blocks.

if this is feasible
1 - would i set it on a sand base
2 - would you have any suggestions on how to deal with the step into the kitchen which in theory would also need to be raised but would then have a knock on effect to the door size.

i know it is not ideal but if i could do something as a holding job i would be at least covering up some of the dreadful concrete until i replace the lot.

hope you can help, many thanks


forum answer Tony McCormack - 03 May 2002
Have a read of the Laying Blocks over an Existing Base page, John - does that help?

As for the kitchen step, I'm not with you. If you elevate the level of the patio by laying Classico Paving over the ex concrete, how will this impinge upon the kitchen step? If you have, say, a 150mm step from ex patio to kitchen threshold, then by laying the pavers over the ex patio, that would elevate the paving level by approx 90mm, reducing the step height to 60mm (more of a trip than a step), but there's no need to start fiddling with doors, as far as I can see!  smile

Novice John
06 May 2002
Thanks for your response and referall to LAYING BLOCKS OVER EXISTING BASE.i did not give you sufficient information on the existing 'step' which in practise is only a 'trip' as its depth ex-patio is only 40mm.
Tony McCormack
06 May 2002
So, is the existing concrete patio only 40mm below the kitchen step threshold, John? Bloody 'eck! There's summat not right there. Extrenal ground or paving level should be 150mm below internal floor level. sulk
Novice John
06 May 2002
Unfortunately my whole house extension was carried out by a company that at the time used to tether their horses up outside and for some reason wore masks throughout the whole job.perhaps i should have suspected something at the time !

the kitchen door though that i describe enters a utility room before the kitchen proper so at least i have a flood barrier.
however i am stuck with what i,ve got,any suggestions on how to overcome?

Tony McCormack
06 May 2002
Aaah! Wayne, Autrey & Rogers, the famous Western Builders known to many as John, Gene and Roy. wink

There's been a lot of new developments in treshold drains to aid compliance with Part M of the Building Regs for disabled access,. RMC have a channel called 'ReadyStep', IIRC and Hepworth have a slot drain that can be used. These help create a safe flood barrier at doorways where the internal floor level is flush with, or only slightly higher than, the external paving level.

They're worth taking a look at - your local BM should have one or more sytems in stock, and they're all under 30 quid, or thereabouts.

I'll dig out more info, if you need it, but your BM should have the tech literature and all the fancy pictures you need.

Novice John
07 May 2002
Thanks for the info. on drains.
however it would seem that i still would not overcome the problem of the paving blocks being some 55mm higher than the step level and therefore a trip risk. this would mean i presume that i could not put the pavers on top of the concrete sub-basewithout structural alterations to the step and door ? (which would make it a non-starter)
Tony McCormack
07 May 2002
If your patio paving is going to be higher than the internal floor level, then it's time to start again and get the levels right, John. You're just asking for trouble making a patio 50+ mm higher than the step.
Forum Question Stone block paving - Richard - 08 May 2002
Hi Tony,

Saw a recently block-paved area that looked excellent, and wondered if you could help identify the product?

They had used what seem to be real stone blocks, 150mm x 225mm and 225mm x 300mm and 50mm thick. The surface was "really grippy", and a mix of grey/browny flecked colours.

Any idea what this was? I guess if it was stone the cost would be £££££!


forum answer Tony McCormack - 10 May 2002
There's a few UK manufacturers that are knocking out sawn stone setts that can be laid in the same manner as block paving. Marshalls do them, as do Farrar's in Keighley. Both of these are genuine York Stone setts and of the highest quality.

However, there are also a lot of imports coming in from India, China, South America and also from Southern Europe. Some of these may well be quality products, manufactured from a suitable local stone by dirt cheap labour then shipped over here and sold at a price slightly below that of UK-original materials, but a lot of what I have seen has been of dubious quality. Flakey, crumbly or overly laminated and aimed at the unsuspecting Garden Centre market rather than the more knowledgeable Builders' Merchants.

As most of the imported material does not carry any agrement certificates or verifiable BS or even ASTM compliance, you have to be very wary about what you buy and who you buy from. BMs are usually very careful when it comes to their suppliers, and most of the specialist stone merchants will give an honest opinion on their stock, but the GCs will sell whatever they think the general public will like the look of, regardless of long-term quality.

From your description, I suspect these are the genuine yorkstone setts. Have a look at Farrar's website as they offer a nice range of widths and lengths.

15 May 2002
Hi Tony,

I looked at Farrar's website (never heard of them before). The thumbnails were a bit small, but their setts didn't quite look like the stuff I saw. The edges were a sharp 90° rather than a chamfered edge. I'll try and find what it was and post back.


Tony McCormack
15 May 2002
A chamfered edge? Marshalls offer that, as a special option - have you looked at their site?

Can you get a picture, Richard?

Forum Question Soft Sand - Keith Miller - 08 May 2002
I have a lot of soft sand left over after building a wall in the garden. Can I use this at all when laying block paving?
forum answer Tony McCormack - 10 May 2002
No. Soft sand has too high a clay content to be used as a bedding material. It will turn to mush when wet and squeeze up through the joints, leading to settlement.
Keith Miller
10 May 2002.
OK thank you.
Forum Question How many tons of scalpings and sand? - Gary Webster - 12 May 2002
My local building supplier supplies Scalpings and sharp sand by the ton. Is there a calculation or general rule for how much I will need for my drive (approx 10 squared meters).  

Many Thanks, Gary Webster.

forum answer Tony McCormack - 12 May 2002
Hi Gary,

I answered this in my reply to your email, yesterday (Saturday)

This information is given on the Sub-base page and on the Screeding page.

Forum Question Power washing - Paul C - 13 May 2002
I just had a new cement paver driveway put in. I would like to have it sealed. The contractor reccomended a power wash before sealing to remove any cement stains from installation and any others that occured since installation two weeks ago. My concern is that power washing will remove some of the joint sand. Would joint sand have to be replaced and/or vibrated in again after a power wash?
forum answer Tony McCormack - 14 May 2002
Yes - power washing will blast out the jointing sand, and it will soak the blocks, so they'll need to dry before sealing.

I wouldn't seal a driveway so soon after laying. I'd leave it until the back end of the summer, give the jointing sand time to settle and bed in properly and to ensure I'm not sealing in effloresence, which is a common feature of concrete (not bloody cement!!!) pavers.

Forum Question That sinking feeling! - Ian - 15 May 2002
Hi, My block paving driveway has sunk slightly in a 1.5 sq.m. section (where my wife parked her car with a heavy load in the boot!) - could you please advise me how to carry-out a DIY repair job and without having to resort to hiring a whacker plate.

Also any recommendations about best brand of weedkiller for the drive which won't discolour the pavers?

forum answer Tony McCormack - 15 May 2002
Hi Ian,

look at the Repair and Maintenance page for guidance on how to lift and relay the sunken paving. You can re-consolidate using a rubber "clonker" (see Tools page) or even by hammering a timber board laid over the replaced paving.

Don't forget the jointing sand - it's absolutely essential!

Weedkiller - we normally use Sodium Chlorate, but Pathclear or Tumbleweed is fine.

Forum Question Losing joint sand - Almara - 27 May 2002
The foot of my block paved driveway is on a slope and the joints are wider than elsewhere in the driveway and as a result I lose jointing sand in heavy rain. I recently had driveway power washed and sealed - fresh jointing sand was added after sealing and if anything the problem is worse. Have you any tips/sugggestions as to how I might keep sand in place.



forum answer Tony McCormack - 27 May 2002
Hi Alex,

Is there some reason why the joints are wider at the threshold of your driveway? They should all be the same size, really - around 3mm.

Anyway, there's a couple of ways to keep the jointing sand in place. The simplest is to use a "Joint Stabilising Fluid", such as Keybond by Marshalls. This is, basically, a PVA glue that is diluted with clean water and allowed to soak into the joints whereupon it sets and binds the sand grains together.

The other option is to use a paving sealant (see Sealants page). This does more or less the same job of binding the sand grains together, but also creates a seal over the entire pavement.

Whereas the keybond-type products seal only the joints and have no discernable affect on the appearance of the paving itself, the acrylic or urethane sealants give the blockwork a sort of 'varnished' appearance that, to be honest, isn't to everone's taste.

From personal experience, the urethane sealants do the best job, but, if you don't want the semi-glossy look, try the keybond and see how it fares over the first season. We find that, for the best protection, the Joint Stabilising Fluids need re-applying every couple of years, but they are only a fraction of the cost of a quality acrylic/urethane sealant.

It should be noted that with clay pavers, the 'varnishing' effect of sealants is far less noticeable than it is with concrete blocks and, because the joint widths are so variable (6-10mm wide in extreme circs), it's well worth considering the use of a decent Sealant on this type of paving.


Almara - 29 May 2002 Thanks for the very prompt and helpful response to my "loose sand" query - I'll certainly give Keybond a try.

You ask if there's any reason why the joints are wider - I'm not sure why. There is some subsidence in that area - is it likely that this is causing the joints to widen or will it be the wider joints causing the subsidence? In either event, would it make sense to deal with the subsidence before resorting to Keybond?



Tony McCormack
29 May 2002
Bit of a chicken and egg problem that one, Alex. The settlement could cause the joints to open up, but open joints make it easier for water to invade the bedding and sub-base which could cause settlement. Whatever, it needs looking at before you spend good money on the Keybond or a sealant.

Take up a few of the blocks (see Maintenenace and Repair page) and check the bedding/sub-base before relaying the blocks to the correct level. Once you've got the blocks back to the correct level,and the joints re-sanded, then you can apply the Keybond.

Forum Question Driveway Ruts - Jerry - 29 May 2002
My paving stone driveway is 10 years old and has developed tire ruts no more than 25 mm deep. The sub-base is 100 mm crushed stone with 35-40 mm sharp sand as the base and in the joints. The drive slopes gradually from the garage to the street and drains OK. The problem here in New Hampshire is what we call "frost heaves", where the ground rises during deep freezes and resettles when it thaws. Driving over that gradually creates slight ruts
Can I re-level the pavers with a vibrator plate (wacker) without removing the pavers? If so, wet or dry? Ocassionally, I'll lift pavers in an area, add sand, and level with a rubber mallet, but that's too much work to do over the whole length. Besides, the ruts eventually come back. Renting a wacker plate would be much easier, but I need to know if it will work or not. Or should I just learn to live with the ruts?
forum answer Tony McCormack - 29 May 2002
Hi Jerry,

there's no effective way to eliminate the ruts (known as channellisation) without removing the blocks. I'd suggest lifting up an area at least one block wider than the affected area, and taking a look at the sub-base layer. You may need to consider scraping out the bedding sand and topping-up the sub-base rather than keep adding sand.

If the sub-base itself is badly affected, it might be worth lifting the lot and putting in a separation membrane (see Geo-Membranes page) beneath the sub-base, relaying the sub-base, the bedding and then the blocks - not the sort of job you can do in an hour or two, I know, but probably more effective in the long term.

Anyway, assuming the sub-base is reasonable, and doesn't need to be excavated - add more sand to the bedding layer, lightly compact it with the plate compactor and then screed it out to level. Replace the blocks, brush in the jointing sand, compact the lot with the plate, and then treat yourself to a well-earned pint. smile

Try and find genuine jointing sand rather than using the same stuff that's used for bedding. The grain size really is critical to generating sufficient friction between adjacent blocks to help them carry the load. If, as you hint, they've previously been jointed with any old sand, then that won't be helping matters.

If the channellisation keeps re-appearing, it suggests the sub-base is inadequate and may need to be replaced to below the frost limit, which will be what is known over here as a right bloody ball-acher!

Have you had a sealant applied to the blocks at all, Jerry? That can help reduce some channellisation, but I've not much experience of frost heave damage, so I can't swear it would be a definite help.

30 May 2002
Hi Tony:
Thanks for your prompt and informative reply. Yours is one of the few web sites where I can get detailed, expert advise; most others simply push their product as the answer to every inquiry. Although your answer wasn't what I'd hoped, it saved me the frustration of using the wacker alone and finding out that it doesn't work.

When the tarmac was removed before laying the pavers, we found the sub-base itself exhibited ruts. The contractor filled and leveled it before laying the sand bed for the pavers. I suspect it has happened again either due to soil pumping from the bottom or sand migration from the top; probably both. If I have it properly repaired, I'll have separation membranes laid on both sides of the sub-base.

I'll have to look for "jointing" sand.  Bagged sand here is either smooth (play) or sharp (masonry). Contractors who buy bulk sand probably have more grades to choose from. I have applied solvent-based acrylic sealers (5 gallons @ $25 USD/gallon) twice, with unsatisfactory results. I have a hexagonal pattern in red and gray pavers. The sealer looks great for the first few months (the wet look deepens the red), but then the red pavers wear and fade unevenly. The acrylic coating gradually whitens. more pronounced in the surface indentations than on top of each red paver. I also sprayed it once with solvent alone with the same results. Based on your sealants page, polyurethane would probably be a better choice. Can that be applied over acrylic, or would I have to stripe it off?

The orginal contractor (from Portland, ME), the paver and sealant manufacturers (both from Montreal) are all out of business. And even with as little as I know, its more than the local suppliers and contractors I've talked to about paving stone driveways. So its likely to be quite some time before I'm confident about hiring another contractor to do a proper repair. (Over here we'd call that work a ball-buster.)

Meanwhile, I think I'll have a pint anyhow. (I like Samuel Smith Oatmeal Stout, when I can find it.)

Forum Question Lay Blocks On Concete? - Big Chas Broon - 30 May 2002
My driveway is concrete and I would like to know if it is possible to lay blocks on this rather than dig it up (obvioulsy I will need a bedding layer of sand). The concrete is sound. In the past year I have several Skip lorries on it and a readymix wagon with 10 tonnes of concrete in it.

There is also a border at the side of the drive this is about 1M wide and is only 30mm higher than the main part. Is it possible to take this taper this out with sand or should the higher part be taken out completely?


Ooops. I've had a good look at the site now and realise that the answer to the first part of my question is already answered, (see Laying on a base page) I need to core drill 50-75 mm holes at 2m centres for drainage.

What a great site there is so much here. I have been considering laying my own block drive for a while but was a bit nervous but I reckon that with the advice here I cant go too wrong.

I'd still like to know about this small, tiny step of 30mm can this be taken out with the screeding layer or should the sand be of a uniform thickness?

forum answer Tony McCormack - 31 May 2002
The bedding layer needs to be fairly uniform in depth or you get differential settlement. +/- 10mm is the limit, really, so I'd suggest you get rid of the 30mm lip.

You only lay block paving once - might as well get it right. smiley

Forum Question Level for Block Paving against DPC - AC
Advice is usually that patios etc should be two courses below the DPC assuming that the DPC is a thin layer between brick courses. However, the DPC in the outer skin of our bungalow is made up of two courses of engineering bricks.  What level should a patio be in this case?  Thanks.
forum answer Tony McCormack
There's probably a polymer dpc on top of the two courses of Engineering Brickwork. Is there any other paving around the house? If so, check the level - it will probably be levelled with the bottom of these 2 courses, ie, 150mm below the dpc.

How old is the property?

AC Hi Tony,

The house was built in the late 40's as far as I know. Because of the sloping plot, there are various bits of paving, concrete etc which are at various levels from 4 courses below the bottom of the eng bwk (foundation level) to level with the top of the eng bwk.

I cannot see any sign of any polymer DPC on top of the eng bwk but note that the polymer DPC in the inner side of the cavity is level with the bottom of the eng bwk in the outer side of the cavity. Inside the house the solid floors are damp proofed by a tar layer holding down the wooden floor blocks, which is level with the polymer DPC in the inner face of the cavity.

So a patio level with the bottom of the eng bwk would be at the same level as the floor indoors. Would this be too high, since our soil is heavy clay, prone to waterlogging in winter.

Thanks - Andy

Tony McCormack I had it in my mimd that this may be a more modern property, Andy, with a cunningly disguised dpc, but it's obviously not.

From what you tell me, I would work on a max paving level of 150mm below internal floor level, ie, 2 courses below the eng bwk. If you wanted to go lower than that, it wouldn't be a problem, but most properties built since the mid 1930s rely on a minimum level diff of 6" (150mm) between internal floor level and external ground level.

How does that fit in with your plans?

Forum Question Bases for block paving vs. flagstones - Matt Taylor
I have been looking at your site. Lots of great information here and well explained too!

I have a patio around the rear of my house that I want to redo. I was thinking of either flagstones or block paving. One question that came to my mind regards the foundation. With flagstones, you recommend just sand as the base (possibly with some cement added). However, with block paving, you recommend first a layer of hardcore and then sand on top of this. Why does block paving require an extra layer?

Thanks for your help,

forum answer Tony McCormack
There are a several reasons, Matt. The first is that block paving uses much smaller elements that are not able to spread the load as does a larger unit flag. This only applies to flags that are 450x450mm or more. The small element pavings, ie, flags of less than 450mm x 450mm, also need a sub-base layer to help them carry the imposed loads.

Secondly, a sub-base helps ensure a regular thickness of laying course material can be used. which, in turn, helps avoid what is known as differential settlement. It  also eliminates any deviations in the level or 'hardness' (CBR) of the sub-grade, creating a suitable and solid surface for the actual paving.

Thirdly, most block paving is subjected to vehicular traffic and so a sub-base is essential otherwise the paving would just 'rut'.

While the 3rd reason doesn't apply to patios, the first two reasons apply to ALL block pavements, even simple patios or paths. Obviously, on your own property, you could choose to disregard this advice, but then your paving will settle over time and end up looking a right bloody mess!


Previous Page | Main Index | Block Paving Index | Next Page arrow

spacer milonic
Brew Cabin Archive
navigation dhtml
courtesy of Milonic