The Brew Cabin

I had a small patio area (stonemarkets weathered york random slabs) laid by a contractor about 5 years ago and he used a dry-mix mortar to point. After a couple of years it crumbled in parts and a year later the odd weed would come through. Worse still when I used a pressure washer to clean the patio the pointing was blasted out entirely in many places.

I have just laid the same slabs down the side of my house (and it certainly looks better than what the contractor did - and a lot cheaper!) but am unsure which pointing method to use. Is it unreasonable to expect the previous pointing method to withstand a pressure washer or is it just the way it was done that caused it to fail? I'm going to rake out all the old pointing and do the whole lot in one go - but which method should/would withstand the use of a PW? GeoFix was recommended to me but apart from the expense it doesn't appear to be that popular throughout this site - and a great site it is too.

I'd go for a standard Class II mortar, Tony. If the flags are well-bedded and there's no movement to engender cracks, it will be fine and will be able to withstand the blast from a typical domestic pressure washer. You could add a measure of SBR, a hardening agent, to get a better bond with the paving and an even harder finish, if you were concerned.

Dry jointing isn't suitable for riven paving that will be pressure washed - it's just a way of filling the gaps rather than creating a sound joint.

GeoFix, as you say, isn't the cheapest jollop on the market, and I have reservations about its use in wider joints because it does not bond to the paving itself. Even on relatively tight joints (6mm or less) I've managed to blast out GeoFix with a small Kew power washer.

I know mortar can be messy and is slow work if you're not used to it, but it's still the best option on these small domestic patios.

I was afraid you might recommend the usual mortar route which, by my experience, is a real pain the butt!! No matter how careful I seem to be I always end up with a certain amount of staining on the slabs. I will try your suggested two trowel method and hope that makes a better job of it.

Thanks for the quick response.

If you're really, really crap at mortar pointing, you can get a roll of 50-75mm wide masking tape or packing box tape and use that to protect the edges of the flags.

As we always said to the apprentices - TAKE YOUR TIME! And hurry up! ;)

Nice idea but the time it takes to mask up I could really, really take my time to absolutely ensure all the muck goes in the gaps and not over the flags! I wouldn't necessarily call myself a complete novice but I'm very picky when it comes to getting a good job done, which invariably means taking twice as long as maybe it should do - much to the annoyance of my wife although she always loves the results. Never bloody satisfied are they!!

Thanks again.