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Vapour Block Primers - How and When They Should Be Used

We're going to talk about vapour block primers and moisture barriers, and how they are used and when they should be used in your applications out in the field.

There's a lot of talk about using a vapour barrier on a mineral surface, and that is something that is either concrete or a screed, a sand cement screed rendered masonry. There are two things that retained dampness can create with waterproofing membranes, or screeds with tile systems.

One is, if you are using a membrane over a damp substrate, and you've got rising damp, obviously you can blister the membrane, particularly if it's outside. The other one, which we see often with tiling systems, is the efflorescence phenomenon. So, everyone's got deadlines, and jobs have to be done, and sometimes you've gone to do a job and it's retained moisture in the concrete or the screed. It could be dry, surface dry, but retained moisture's in there because the fact is you've got morning dew, the dew overnight, the morning dew is on there. Or it has rained, and then the rain evaporates, but it's been absorbed into that substrate because it's porous.

And so everyone's trying to find a quick way to finish the job. The best way to be doing this is with something like the Gripset E60, which is our water-based epoxy primer. It's a fantastic product. You can use it, it's a one to one ratio. You mix it up and you apply that, and it's perfect on mineral surface because it will have tenacious adhesion as an epoxy onto that substrate. Once it's dried, it has a chemical process because it's two components. Once that's dried you can get your membrane over there, and if there's any retained moisture in that screed or the concrete, it won't blister or impact the adhesion of the membrane on the substrate with blistering phenomenon.

The other part of it though to realize is that we're seeing more and more tilers now looking at things like a two-part epoxy on top of the screed. Because they've obviously laid a screed, they go over and under. There's a screed laid on a membrane, and then that screed might have retained moisture, and obviously it's waiting for it to evaporate and it doesn't dry as quick because it's a non-porous surface underneath that. Putting an epoxy primer on top allows you to get over that a little bit quicker. You should always have a moisture gauge with you, and if you don't have one, invest in one. If you're a serious water proofer, it's worthwhile investing in a moisture meter, and understanding what the moisture levels are in screeds, on concrete.

A good example of the trades that do this are the flooring guys and timber. They always measure the moisture levels in concrete before they lay things like timber or parquetry down. Waterproofer’s should be this as well. It's a really good quality measure. It will allow you to understand exactly what the level of moisture is in that substrate you're going on.

But the water-based epoxy on a screed that allows you to ensure that the screed is not taking ages to dry, even if you've got another membrane on there, or you’ve got to get your tile adhesive onto it. And so the other advantage of that is, is that if you're putting something like the epoxy on the screed, you're not going to get the efflorescence issue with salts coming out of the screed because it blocks it. And that is a big problem in the industry at the moment. Where you might have an external area where it is not leaking, but you've got all that efflorescence and salt staining through the grout joints coming up. That's really coming up through the cement bit of screed, through the coming in contact with tile adhesives, the grout, and then staining it. It's a big discussion point.

The other alternative we have, many of you have been using our Gripset P10, which is our polyurethane vapor barrier. This is not water based and it's not solvent based. It's 100% solids, and so when that goes onto a substrate like a screed or concrete, the difference between that and the Gripset E60, which we get lots of questions, E60 as an epoxy has high adhesion to the substrate. Gripset P10 penetrates because it's got very low particle size, and it will seep into even quite dense concrete surfaces. So when you will find a pull off test, you will see that it actually will pull the screed of the concrete out with it because it has penetrated quite deep. The difference with this is that it has a higher coverage per square meter, per litre. It's moisture-curing, so it will cure with the level of moisture in the screed or the ambient conditions.

So, if there's some damp area it actually dries better than in dry heat. But the big advantage of Gripset P10 is that being 100% solids, it's got outstanding resistance to solvents. So, this product is used a lot, even though we don't make a solvent based membrane or coating, but we use it a lot with flooring guys. Solvent based materials will bond to the Gripset P10 very well because it won't break it down. So, it's another option for you.

In the range, I have to say the E60 has to be the common practice where guys are using two pack water based epoxies on the substrates. And the other advantage of the two pack water base is that we've got a potable water certificate with the E60, so things like fish ponds, water features, etc., it's safe to use there. Water tanks, and there's no emission of any harmful chemicals at all. And it also blocks that moisture that's coming through from the sides or coming out through a fish pond or water feature, which often undoes a lot of membrane applications in those situations.

If you've got any more questions on the E60, or moisture barriers, or vapour barriers and when to use them, fire away at our technical services department. We're here to help.