Step-by-Step Guide to Block Pavement Construction

It's a good idea to have a plan before any ground is broken.

On this project, a construction drawing was prepared in advance (as part of the pavingexpert.com design service ), so that the client could be sure they were happy with the proposed dimensions and layout, and that the contractor knew exactly what was expected.

The cost of preparing such a drawing is often recouped in the time saved by not having to argue over just where the edge course was to go, and which bits were to have kerbs, etc. A good site layout plan is an extremely useful addition to a written specification and/or Bill of Quantities, as each party knows exactly what is to be constructed.

The area of the planned paving should be marked out in advance, allowing approximately 300mm over at each free edge to make the handling of materials and haunching of edgings or kerbs that much easier. Sand, a spray marker or string lines and stakes can be used to mark out the area - see Setting Out page.

Dig off as required, and dispose of spoil. On this project, a 3.5 tonne mini-digger was hired-in to undertake the excavation which with a total area of 115m² plus extra for drainage, flower beds, etc., would generate around 30m³ of spoil to be carted off-site to a licensed landfill site. The excavator would also help to spread the sub-base material.

The excavation depth for a typical domestic driveway is 200-250mm below finished paving level, based on 100-150mm sub-base, 40mm sand bed and 50mm block. Typical builders' skips hold approximately 4.5 m³ of excavated material, which, assuming a 200mm dig depth, works out that each 20-25 m² of paving will require 1 skip to dispose of spoil. Remember that excavated material bulks up by 20-30%, so each 1m³ dug out will become 1.3m³ for disposal.

Rather than rely on a fleet of around 7 or more skips, the spoil was collected by a Grab Wagon, which can collect roughly 9m³ at a time and works out cheaper than using skips.

Make sure any soft spots are excavated: they should be backfilled with compacted sub-base material. Remember, it's better to dig too deeply than too shallow.

See also sub-grades page.

Spread, level and compact a minimum 100mm thick layer of sub-base material.

The sub-base should be profiled or graded to match the planned profile of the finished paving and should be accurate to ±10mm. There should be no voids within the sub-base - any such voids should be filled with stone dust or grit sand and compacted before placing the laying course.

Set up taut string lines to guide line and level of edge courses and kerbs.

Edge course bricks and kerbs should be laid onto a concrete bed. Check that straight lines are indeed straight, and that the curves are 'sweet'. Once satisfied with the lines and curves, edge courses and kerbs should be solidly haunched with concrete at least 75mm thick.

The client requires a small clay bull-nosed kerb to the flower bed edges of the new driveway, so these are installed first, laying onto a concrete bed and buttering the joints between each of the kerb units to give a neat and tidy finish. They are then robustly haunched with fresh concrete.

Wherever there is a kerb, that will act as the restraining edge so the edge courses does not need to be laid on concrete, but this contractor prefers to have very firm and reliable edges, so the decorative edge course, comprising a 200mm wide ebony brown brick with a 100mm wide red-multi contrast and then a final 100mm wide ebony brick is laid on a lean-mix concrete.

Spread, level and compact laying course sand, and screed to correct level.

When compacted, the laying course sand should be 25-40mm deep. The key to successful screeding is creating a smooth, even and flowing surface on which to lay the bricks. The surface profile of the screeded laying course more or less matches that of the finished pavement, so attention to detail is essential.

The plan calls for a 45° pattern, so a starter course of blocks square to the building is established. 90° patterns are best started at a corner or main edge of the building.

Once all the full blocks are laid, they need to be checked for alignment by using a string line stretched along the diagonal courses and adjusting as necessary, using the alignment bar tool as shown in the photograph. Clay pavers often require significant re-alignment as the imperfect rectangles are prone to drifting off-line during the laying process. Concrete blocks, being moulded as perfect rectangles, usually suffer less drift and so require less re-alignment, but they should always be checked prior to cutting-in.

Once the alignment has been checked and verified, the edges can be cut in .

Fix Recess Trays and gully covers, if necessary.

Check paving for compliance .

The final task is jointing . This is done once all the cutting-in has been completed, and the compliance checks carried out.

Kiln-dried jointing sand is spread over the block surface and swept into the joints using a soft brush.

Excess jointing sand can be swept off the surface and it is now ready to be used.

The jointing sand may settle over the first few weeks and should be topped up as soon as this becomes apparent. Many block pavements, of both clay and concrete pavers, may exhibit efflorescence in their early life but this should disappear within 12 months.

Regular maintenance will keep the pavement in tip-top condition and some clients will want to consider the use of a sealant to protect their investment from accidental staining.