Topping up pointing - Can i top up or do i need to remove?

[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

[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.

[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

[harding]

oh well - thanks for the info... I think i'll leave it for now then

[sy76uk]

Fine pea gravel looks nice in wide joint's sometimes.