Block Paving | Driveways | Sheffield South Yorkshire



Block Paving - Step by Step General Information: Paving blocks should be laid in accordance with BS7533 "Pavements constructed with clay, natural stone or concrete pavers - Part 3: Code of Practice for laying precast concrete paving, black and clay pavers for flexible pavements." All kerb units, edgings, dished channels and line drainage should be laid in accordance with BS7533: Part 6 - "Code of Practice for laying natural stone, precast concrete and clay kerb units". The following information is a guide. The British Standards should be referred to for detailed recommendations. Production Specification: Where appropriate Brett concrete block paving is manufactured in accordance with BS6717: -"Precast unreinforced concrete paving blocks - Requirements and test method". The British Standard required that the average tensile splitting strength is not less than 3.9MPa and for any individual block is not less than 2.9MPa. Tolerance is +3mm on thickness and +2mm on plan dimensions. Design Guide: This guide is based on BS7533: Part 2: = "Guide for structural design of lightly trafficked pavements constructed of clay pavers or precast concrete paving blacks" which should be referred to for more detailed information. For heavy duty use the following should be referred to BS7533: Part 1: - "Guide for the structural design of heavy duty pavements constructed of clay pavers or precast concrete paving blocks." Step 1 The all - important preparation 1. Mark out the area to be paved and remove all the topsoil or existing surfacing to a depth so that the finished level is at least 150mm below the damp proof course of any adjoining house or building. If the area is flat it will be necessary; for drainage purposes, to create a slight slope during the excavation, dropping 25mm over 1 metre across the width (1:40) and 25mm over 2 metres along the length (1:80). 2. Compact the excavated area with the plate vibrator, digging out any soft spots and filling them with sub-base material. 3. Install surface water drainage channel if required, ie if the paved area slopes towards the house/building or any other place where water run-off would not be welcome. Recessed manhole covers should also be installed at this stage if required. Note: Finished level of paving should be approx 5mm above any drainage point. Step 2 Install all edge restraints, whether kerb's or edgings, by setting firmly in concrete to correct levels. Step 3 Lay over the entire area to be paved a geotext membrane then lay the sub-base material within the edge restraints and compact it firmly with the plate vibrator; depending on how well it compacts, you may need to go over the whole area between 5 and 10 times. It is essential that this sub-base is firm and to the right level. Step 4 Spread the sharp sand to a depth of 50mm, compact it with the plate vibrator and spread a further 15mm of sharp sand over the area as a loose screed. Correctly level the screed with a rigid piece of timber or screed bar drawn along guide rails. Step 5 Lay one course of blocks on the sand along all the edge restraints. They may be laid long ways against the edge ('a stretcher course') or with short side against the edge ('a header course') depending on personal preference. Step 6 Lay the blocks hand tight only; with a joint gap of 2-5mm, starting in one corner, and at the bottom if there is a slope. Notes: 1. Randomly mix and lay blocks from at least 3 packs to ensure even distribution of colour and texture. 2. If laying in herringbone pattern pull a string line across the area at 90° or 45°, as appropriate, and lay the blocks along the line. To start a herringbone pattern either put stretcher blocks along the line with one corner against the edge restraint and fill in the voids later with cut blocks, or use Bishop's Hats, which sit flush against the edge restraint and give you the angle to work from. 3. Pieces smaller than one quarter of a block should be avoided where possible. Step 7 Sweep the area thoroughly after it has been laid - particularly if a block cutter has been used - to remove all chips and fragments. Then check to ensure there are no damaged blocks; if there are any, this is the time to replace them. Step 8 Compact the whole area with two or three passes of the plate vibrator. Step 9 Sweep Jointing Sand over the entire area, ensuring it gets right into all the joints between the blocks. Notes: 1. If there is a recessed manhole cover; care should be taken to avoid any sand getting in between the cover and the frame. Step 10 Vibrate the whole area gain to force down the Jointing Sand and fill any gaps which appear in the joints. Leave any surplus sand on the surface for the wind/rain to wash into joints. Alternatively sweep off the surface and re-sand if necessary.