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Posted: Tue Mar 11, 2014 8:32 pm
by harding
Hello all,

Hopefully this is an easy thing to answer... I have a large patio of flagstones that are in good condition and are solid and seemingly well laid.

The issue that I have is that the pointing is very wide (5cm gaps), and it is a bit low, so the gaps collect loads of rubbish, earth etc. Otherwise the mortar is in good condition, no cracks etc.

My question is can I just top up the mortar on top of the existing, or do I need to remove the mortar that's there? If I do, I think I'm going to have to leave it - its too big a patio/job.

any advice would be greatly appreciated.

Thanks
Lee

Posted: Tue Mar 11, 2014 8:59 pm
by r896neo
Sorry for the bad news but you need to remove it.

You really need 25mm minimum.

If you have at least 20mm to work with you could try a slurry grout like flowpoint but it may not hold properly and is a risk.

Posted: Wed Mar 12, 2014 9:54 am
by Tony McC
Yep, it's almost impossible to get a thin overlay 'top-up' for pointing; it needs some depth to stand a chance of lasting more than a couple of weeks, and 20-25mm is usually regarded as the minimum.

There's a case study of a patio rejointing project here

Posted: Wed Mar 12, 2014 10:29 am
by harding
oh well - thanks for the info... I think i'll leave it for now then :(

Posted: Sat Mar 15, 2014 8:29 pm
by sy76uk
Fine pea gravel looks nice in wide joint's sometimes.