I will soon be laying approx 20 square metres of porcelain floor tiles in the back garden. I have now lifted the previous block paving to make way for these tiles.
My plan was to remove the sand down to the MOT layer, add and wack more MOT, and then lay the tiles using the recommended mortar mix. However I'm now wondering whether I can lay the tiles and the mortar mix straight onto the sand layer as it looks well compacted after years of block paving and foot traffic compression? It would save me digging it all out and skipping it, and paying for more MOT and wacker hire.
Could anybody advise whether this is safe? Are there any good reasons not to do this?
Thanks
Re-use block paving sub base
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Tony McC
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Remove the sand and get rid.
It is considered bad practice to re-use sand previously used as a laying course of (block) paving for various reasons, not least of which is that the loading of the paving (even when it hasn't been used for vehicular traffic) causes the sand grains to crush and reduce their interlock capability. While such sand remains undisturbed beneath the original paving, there is only a low risk of it migrating or of it being washed through by groundwater. However, once it has been disturbed, it's regarded as unsuitable for use as an unbound bedding material.
It would be fine to reclaim the sand and use it in a mortar, if you wished, as that would rely on the cement to bind the sand grains, but its days as a loose material are over, or they should be!
There are other issues, although they are of lesser concern for a patio project - contamination by organic matter; accumulation of excess fines; stratification.....these are all important for high-use commercial pavements but of minimal consequence for your sort of project. Even so, given the cost of porcelain, it really isn't worth spoiling the ship for a ha'p'orth of tar!
It is considered bad practice to re-use sand previously used as a laying course of (block) paving for various reasons, not least of which is that the loading of the paving (even when it hasn't been used for vehicular traffic) causes the sand grains to crush and reduce their interlock capability. While such sand remains undisturbed beneath the original paving, there is only a low risk of it migrating or of it being washed through by groundwater. However, once it has been disturbed, it's regarded as unsuitable for use as an unbound bedding material.
It would be fine to reclaim the sand and use it in a mortar, if you wished, as that would rely on the cement to bind the sand grains, but its days as a loose material are over, or they should be!
There are other issues, although they are of lesser concern for a patio project - contamination by organic matter; accumulation of excess fines; stratification.....these are all important for high-use commercial pavements but of minimal consequence for your sort of project. Even so, given the cost of porcelain, it really isn't worth spoiling the ship for a ha'p'orth of tar!
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Spoony
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Tony McC
- Site Admin
- Posts: 8346
- Joined: Mon Jul 05, 2004 7:27 pm
- Location: Warrington, People's Republic of South Lancashire
- Contact:
The re-use of bedding *is* covered on the main website, in the "Refurbishment of Block Paving" sub-section - https://www.pavingexpert.com/refurb_04#bed-preparation
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