What are the usual brands of cement waterproofing admix ? I phoned a local BM and they were charging 45 quid (immediately discounted to 25 + vat !!) for 5 litres of SBR. Any cheaper alternative as I only need a few trowel-fulls of water-proofed mortar ? Thanks, Simon.
Diluted PVA, 1:4
Use a bit of PVA.
You can buy waterproofing admix (not SBR) in 5 litre containers from the likes of Wickes or B&Q. I don't remember the price, but it was nearer the £10 mark. It often comes combined with plasticiser (although both are available separately, but may be harder to find). SBR is more expensive, but I've never used it -- I believe it's used where the render is expected to be submerged and you also need a bonding agent.
PVA in mortar/render is not a waterproofer, and neither is EVA (sold as waterproof PVA, although it's not really PVA). They are bonding agents. PVA eventually disintegrates on constant/frequent exposure to water.
SBR doesn't "mix" with mortar in the way that pva does and tends to drain out of the mix after a few minutes. I think it probably forms a film on the substrate (usually a concrete floor) and the mortar sets independently on top of that, though with obviously enough resin to bind the particles. You can add some solvent based varnishes to mortar (e.g. Bondaglass G7) so I imagine any paint or varnish will make a waterproof mortar of sorts. Dunno, try it
So what would be best to add ot a 3:1 mortar mix to use as tile cement? I wont do it for anything but an experiment but cant help being curious.
NT
Dunno. Obviously the varnish is soluble in its solvent and the mortar is dispersed in water, so they are basically incompatible but can be forced to coexist in a thickish mix. Once the 2 solvents start to evaporate, it's anyone's guess what will form on top of what. Might be better to treat the wall with varnish mixed with dry sand to give a key to a normal mortar.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.