Last edited 24 Jan 2019

How to lay block paving



[edit] Introduction

Block paving, or brick paving, is commonly used for constructing pavements, patios, driveways and so on. It is may be used due to its decorative aesthetic, ease of installation, and the fact that the bricks or blocks allow for easy remedial work by removing and replacing those that are necessary.

Block paving can be used to achieve many different laying patterns, the most common being the herringbone pattern due to its interlocking strength.

Block paving is a very popular choice for domestic driveways and this article will explain the various stages involved for this particular application (although other applications are very similar).

[edit] Excavation

The first stage, once the area required for block paving has been established, is to excavate to a depth that means the finished surface of the blockwork will be at least 150 mm below the damp-proof course of the adjacent building to the paving (and that it drains away from teh building). The typical excavation depth is 200-250 mm below the finished paving level (this comprises 100-150 mm sub-base, 40 mm sand bed and 50 mm block or brick).

The ground should be excavated to a gradual slope to allow surface water to run away and not pool on the surface. If a drainage system is to be installed, the slope can be directed towards that. The typical slope is a 1 cm drop for every 60 cm length.

A skip may need to be hired to remove the excavated material. The amount of excavated material needing to be removed can be calculated by multiplying the surface area by the dig depth, as well as accounting for 20-30% extra for the bulking-up of the spoil material.

[edit] Edge restraints

Edge restraints are required to frame the block paving. First, string lines should be set up as guides to level the edge courses and kerbs.

The edge course bricks and kerbs should be laid on a concrete foundation using a mortar bed, and hammered in gently, checking the line for the correct level. This edging should then be haunched by applying concrete to the outside up to approximately halfway (roughly 75 mm thick).

At this stage, any drainage should be installed and also haunched with concrete to protect it.

[edit] Sub-base and screeding

The sub-base layer should be a minimum of 100 mm-thick and firmed down using a compacting plate. Making sure the sub-base material is compacted provides a level and strong base for the block paving.

Coarse sand should be spread and levelled on top of the sub-base layer to roughly 25-40 mm deep. It should then be screeded to ensure a smooth and even surface on which the paving can be laid.

[edit] Laying the blocks

Blocks should be laid from one corner at the bottom of the slope. They should be around 10-15 mm above the measured line as this then allows for compacting once they are all in place.

The herringbone pattern provides the strongest interlocking bond and is achieved by setting the blocks at either 45- or 90-degrees to the perpendicular. Those laying the blocks should always work from the paving that has been laid, not the screeded laying course.

Once all laid, the blocks should be carefully checked for alignment by stretching a string line along the diagonal courses. Concrete blocks tend to drift less than clay pavers which can require re-adjustment.

The edges of the paving can then be cut in to fit snug to the edge course. Recess trays and gully covers should be fixed in place if required for drainage,.

[edit] Jointing and finishing

Jointing involves spreading kiln-dried sand over the surface of the block paving and sweeping this into the joints. This can be done whilst compacting the paving down using a compactor plate. Care should be taken to alternately pass over each section of paving at 90-degrees to the previous pass.

Jointing sand may settle over the first few weeks of the block paving being completed, and should be topped up as necessary.

Sealant can be applied to minimise staining.

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[edit] Related articles on Designing Buildings Wiki