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  • paul barker

The use of paving primer, and why it’s necessary for most patios nowadays

As time has gone by paving slabs have got thinner, it wasn’t unusual 10 years ago to get paving slabs that were 40mm thick. Now you order paving slabs and they come 20mm, 18mm thick generally. In some regards that’s a benefit to the installer as they are lighter and easier to cut, but being thinner does have its downsides.

We will use sandstone as an example. Sandstone is pourus, it absorbs water, along with anything that’s in the water. So if you imagine a sandstone paving slab 20mm thick being laid on a bed of damp sand and cement mix, the paving will suck up some of the moisture from the mix. Problems arise when the slab sucks up so much that it can be seen from the surface of the slab.

Unfortunately, in this picture not only have they not used a primer, they havnt laid the slab on a full bed, making it look even worse. Once it’s there , your stuck with it,

What is a primer?

A primer is painted onto the underside of the slab before laying onto a full bed of mortar. It seals the slab from water being sucked up into it and at the same time acts as a very strong glue that creates an extremely strong bond with the cement mix below.

So in summary, use a primer, avoid the reflective staining on the surface of the slabs and at the same time apply some belts and braces!!

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