I am looking for some advice on some pointing that has been started on a Multi Mint Sandstone patio.
The landscapers have used a white Gunable pointing (Larsen GPM). After several issues that required them to pull up and replace damaged stone where they tried to use the product like you would when tiling, resulting in a thin grey film on the stone surface, they tried to follow the instructions and use a gun which has resulted in the below. I'm not happy with the finish but would really appreciate a second opinion.
its not the best and not the worst
the key thing with gun point is that it has to be carefully squirted in and left till just the right moment and then struck
when we use it ( I dont like it) we have 1 knocking up,1 squirting (me) and 1 cleaning the empty tubes
its labour intensive
I have seen much worse but this is way off the best
LLL
Thanks for that. Is there an alternative you would recommend. We wanted a white product but happy to compromise in order to get a better finish. Can the issues be rectified?
In my laymans mind the issue being the joint is not uniform and the stone has white stains where the product has been dripped. I guess I just need to know if my expectations are realistic. This is a £15k plus job for 60m2 of patio and some other hard landscaping.
The suggested solution from the landscaper is that it needs to be sealed so they can then point it like you would a wall tile with a float and a wet mix of the gun point mortar and that the sealant will prevent the mortar from staining the stone.
They already used this method minus sealing it which resulted in perfect pointing but left a white mist over the stone. See below image of this - they decided this was wrong and tore up and discarded 10m2 of paving.
Is it possible to get this kind of finish but without resorting to what I consider to be complete disregard of the instructions for the product?
It just seems like they don't really know what they are doing!!
Should we be looking at a different product or getting someone in who knows what they are doing with this product?
it does seem that they are not sure about this product
I know some blokes use Ardex grout for patios but I never have
my favourites are the 2 part resin mortars vdw 815 and romex D1 but i dont think the range comes in white
the laying of your flags looks pretty good but the pointing is a let down
trying to use larsen as a slurry is not a good idea
sealing first wont work as most good sealers are impregnators
LLL
Thank you. Ok final question and I know it's not an easy one to answer - but what would you suggest is the best solution.
1 - have them finish the pointing as they have done to date to the best of their ability and live with it - they have done about 20m2 of the 60m2
2 - have them use an alternative product as you mention - but this will require removing the pointing or relaying the paving I asssume?
the larsen could only be removed with an angle grinder now which is fraught with danger
when the larsen is squirted in they need to have clean water and a soft brush to hand for any spillages
generally we would install a bags worth and then go over the work with a jointing iron,but leaving the snots in situ
once these snots have dried off we would then brush them off diagonally with a soft coconut broom
cheers LLL
lutonlagerlout wrote:my favourites are the 2 part resin mortars vdw 815 and romex D1 but i dont think the range comes in white
You *can* get coloured versions but they are not 'off-the-shelf' in Britain or Ireland. You have to ask the importers to acquire some on your behalf and pray they can get the requisite quantity rather than be obliged to buy a full pallet. It ain't cheap!
The gun-pointed mess is practically irretrievable, unless you rely on grinding or shot-blasting, which will affect the texture of the stone...and again, it ain't cheap.
The idea of sealing the stone and then grouting with something like Ardex or Mapei needs very, very careful choice of sealant. Many wiill NOT prevent mortar staining from such fine-grained grouts, and the ones I've seen work reasonably well have all been the very glossy, wet-look products, which, IMO, ruin the look of the stone.
A contact in the yorkstone trade reckons one of the better mono-fluoro-silicates works with many of the proprietary jointing mortars, but he's not sure about the tiling grouts.
For me, white mortar, or any attempt at coloured mortar jointing, is a waste of time, money and effort. It *will* be mucky brown in 3 months' time, unless you plan on spending every other weekend washing down the whole pavement....life's too short!
We have been in communications today and they have now proposed we use a Buff Weatherpoint 365 which they have apparently used many times before. Assuming this is appropriate I just need to see what they propose for the current slabs (basically who is going to pay to replace them) - but that's a conversation for tomorrow morning!
So they have spoken to London Stone who supplied the Stone and been told it definitely should have been sealed before pointing. This is not what I was told or indeed what people seem to suggest on this forum. I understood it was better to leave it to effloresce etc and seal after several months.
Regardless I don't see this as an excuse for the messy pointing. They are now proposing to remove it by hand with a chisel and then to clean with an acid....
The most problems we encounter are mortar/resin staining issues on Honed Sandstones, I personally would not install a Honed sandstone patio unless it had been pre-sealed as there is too much risk of things going wrong. The 2 part epoxy resins are great but can be risky on honed sandstones, the single part polymeric like Easy Joint and Weatherpoint are ok and less likely to stain but ar not as durable. We found the best finish we got on honed sandstones was using a flexible exterior tile grout like Flexjoint and made sure we had plenty of sponges available and water to clean as we went along. Also as the tile grout is non permeable you don't get any picture framing occurring afterwards which we have also found when using single part polymerics or the 2 part epoxy resins.
Thanks for that Dave. The guys tried to remove the GPM both by hand and with a grinder but this left marks on the stone from the blade or just chipped the edges. They have agreed to take it all up and replace it which is heartbreaking but seems to be the only solution. They are going to use Weatherpoint which they have used many times before and hopefully there will be no further issues. I genuinely didn't realise there were so many factors to consider and can see now why it's so important to plan exactly what products to use and think through any potential pitfalls before embarking on the job or face the consequences.
