Lafarge Cement - patio laying

While for many the winter season presents an opportunity for rest and hibernation, for builders in the UK it means a chance to catch up on home and garden tasks that have been cast aside since the summer.

A new patio is a popular and relatively low-cost solution for improving the look of a garden. Nevertheless mlaying paving slabs can be both time consuming and problematic. Difficulties often arise from incorrect measuring and consistency of the bedding mortar which can result in an unattractive and irregular result.

The solution is a ready-to-use specialist product, such as Slablayer produced by leading cement suppliers Lafarge. The product is a cement-based solution for laying most types of patio paving. It requires no mixing, and gradually over a period of time, develops hardness to support paving slabs.

Slablayer is available from suppliers of Lafarge Cement products, in 20 kg tear-resistant plastic bags.

Step #1

To work out the quantity of materials you will need, and what laying pattern you want to use, make a scale drawing of your patio or pavement. Try to ensure that cutting of slabs to fit particular shapes or curves is kept to a minimum and consider using pre-cut slab shapes or different coloured patterns if necessary. Prepare the ground by removing all plant matter and topsoil, including a margin of 150mm or more beyond the edges of the area that the patio or paving will cover. Then, dig out to the depth required and lay a substrate of hardcore on top of the level soil. Compact and level the substrate with a roller, vibrating plate or a piece of timber. Once the sub base for the patio has been completed, a weed-suppressing membrane may be placed to prevent unwanted weeds growing through the pointing gaps in the patio. Ensure that enough material has been dug out to allow for the thickness of the slab itself and around 25mm for the Slablayer bed.

Step #2

Set out the work with string lines and level pegs. To avoid puddles on your patio you should plan a crossfall of 1 in 40, which equates to 25mm per metre to provide a run off for rain water. NB: Patios should always fall away from the house so that the rainwater does not flow towards the building, which could cause damp problems. You must also ensure that the patio or pathway does not rise to within 150mm of the damp proof course of the house. Place Slablayer to the required depth of at least 25mm and rake level. As a guide to quantity, three 440mm by 440mm paving stones can be laid with one bag when the Slablayer is used at this thickness. NB: If the temperature is below 5oC and falling, it recommended that construction is delayed until a warmer time of day.

Step #3

Sprinkle the surface with clean tap water using a fine rose or hosepipe until the Slablayer is wet through and rake level again. It is important that the Slablayer is wet throughout without creating standing pools of water on the surface. The size of the soaked area should be just enough to place several slabs easily.

Step #4

Slablayer is suitable for the vast majority of slabs. However, very porous slabs may need to be damped slightly to control excessive suction, as per usual bedding practice. Place the paving slabs, avoiding excessive strain on the back and ensure that they are level and flat. For larger slabs, this may require assistance from a friend or colleague. Use a rubber mallet to tap the slabs into place. Check that the level is correct with a straight edge board and spirit level. Repeat the process, easing slabs into position. Ensure that the joints are evenly spaced, and use spacers if necessary, and make sure that no cement material is on the slabs as this will result in staining.

Step #5

If you wish to point the slabs, wait one or two days after laying and fill the joints between them with Lafarge ready-to-use pre-mixed mortar mix. Alternatively a dry mix of Lafarge Slablayer can be poured over the area, brushed into the joints and compacted with the edge of a piece of wood. Remove any excess mortar from the surface of the slab. Sprinkle with clean water using a fine rose and point with a pointing tool. You should not walk on your newly laid patio for at least 48 hours to allow the material to set. We recommend covering the slabs with plastic sheeting for protection during this period. A pressure wash once every two or three years is generally sufficient to ensure the patio or pathway will continue to look great.

All equipment should be cleaned with water immediately after use. Do not flush down drains. Dispose of empty bags or surplus product to a place authorised to accept builders’ waste.

For a video guide, visit the Lafarge YouTube channel at:

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