Laying new slabs on old base

[JonnyM]

I have an area of patio where the paving has cracked and settled unevenly. The base is grit sand. I want to take up the old slabs and lay new on the old base butting up to the existing, good area of patio.
How should I prepare the base? Can I just put another layer of grit sand down and screed?
Thanks
Jon

[84-1093879891]

If the grit sand is clean and not riddled with roots or contaminated with soil from worms and the like, then it could be re-used. The simplest way would be to rake it loose, add a sprinkling of cement, mix that in and use it to lay the new flagstones. You'll probably need a few barrows of additional grit sand, so make sure you order some when you're at the BM yard.

[JonnyM]

Tony,
Thanks very much for the quick response. I havn't taken all the slabs up yet but under the ones I have it all seems pretty clean. Presumably I should dig out any areas where there is soil and backfill with the grit sand ?

Also my local branch of Jewson don't seem to have heard of Jointing Sand - is it called anything else?

Thanks again for your help - what a great web site!!!

Regards

Jon

[JonnyM]

Morning Tony, Just taken the old slabs up to find that most of the bedding is soft sand - suppost that's why it slumped!

Can I get away with removing half of the soft sand and replacing with sharp sand (and adding some cement)or is it all going to have to come out?

Why is life never simple?

Thanks

Jon

[84-1093879891]

You should be ok replacing half or more of the old soft sand with a grit/sharp sand, and adding a sprerinkling of cement (no need to use more than 10%) will help enormously.

As for Jointing Sand, I can't believe Jewsons haven't heard of it - I know that some of the numpties the employ behind the counter aren't exactly masterminds, but every BM in the land must be selling at least 20 bags of jointing sand every day of the week. The full name is "kiln-dried jointing sand for block paving compliant with Table D3 BS7533:Part 3", so they may know it as 'kiln-dried sand', or 'block paving sand', or 'dry sand', or 'silica sand', but they really ought to know what you meant when asking for "Jointing Sand"!