Skill Builder Guides & reviews for building and construction
When it comes to sealants there are very few on the market that can match CT1, says Roger Bisby.
Not only is it strong and flexible it can also seal damp surfaces. I have tried many products that claim to do this but not all of them work. I first started using it when I was working on swimming pools because it was the only one the pool companies recommended for use in chlorinated water.
WT1 is essentially the same product as CT1 but it is in a can rather than a tube. This allows you to use it on flat roofs, concrete floors and balconies as well as walls. You can even use it to tank out a ply-lined wet room prior to tiling.
Having used other liquid membranes I was initially thinking of applying it with a roller but I soon discovered that it is easier to pour it from the can and then use a trowel or a squeegee to spread it out.
The self-smoothing properties allow you to spread it out as you would a self-levelling screed and then you can leave it to settle down. If there are cracks or holes in the surface it will find them and seep down so you’re better off sealing anything obvious before you start.
The self-smoothing properties allow you to spread it out as you would a self-levelling screed and then you can leave it to settle down. If there are cracks or holes in the surface it will find them and seep down so you’re better off sealing anything obvious before you start.
In many cases you will want to continue the membrane up the wall in one continuous flowing coat. In fact, it is better to start on the wall and then work your way onto the flat surface.
You can brush it on the wall – if you are covering lead this might be the only way, but if the wall is straight you can also trowel it up from bottom to top. Bear in mind that it will slump if you put on too thick a coat, so if you are looking for a belt and braces treatment you are better off putting another coat on later on. You can then over-paint it when it dries.
If you have a leaking felt roof you have the choice of stripping the felt off or going over the top with WT1. If there are blisters it is best to cut them and then feed the compound under the felt to stick it down before you go over the whole roof.
If you want to strip the roof back to the plywood deck you can then clean off the worst of the bitumen and then apply WT1 over the plywood to form a finished surface. Personally, I would use a non-woven membrane embedded in the WT1 over any joints in the plywood and then apply another coat over that.
There are a great many other uses for WT1 but if you are not sure about its suitability, the company has a good technical department to give you advice.
