Paint or membrane first

[maglite]

Hello All,

I was hoping that someone might be able to point me in the right direction.
We have had 6mm villaboard fitted to all the wet area walls.
Is it normal practise to apply some sealer/undercoat to the walls first or simply apply a coat of membrane direct to the bare villaboard.

Many thanks in advance.
Steve

[johnc]

There should be a sealer recommended for the membrane you have chosen. It's simply a case of applying the sealer, then straight over with first coat followed by a second after a specified time and the jobs done. Beats fibreglass and tile adhesive seems to like it.

JohnC

[ian]

I was hoping that someone might be able to point me in the right direction.
We have had 6mm villaboard fitted to all the wet area walls.
Is it normal practise to apply some sealer/undercoat to the walls first or simply apply a coat of membrane direct to the bare villaboard.

Go with a good membrane and follow the directions for the product. I've done this twice now, once for an external deck over the laundry and once for the upstairs bathroom.
In both cases the process was one coat of membrane as an undercoat, then a bond breaker at evey corner, then a second coat of membrane with reinforcing mesh, and then a third and possibly a fourth coat of membrane.
The bond breaker is essential if you want long lasting waterproof joints.

[maglite]

Many thanks JohnC & Ian,

There i was thinking that this would be relatively simple
Can you please fill me in on what the bondbreaker and reinforcing mesh actually does?
Is it reasonably easier to do yourself or would i be better off paying someone to do it ie builder or tiler.

Thanks
Steve

[Metung]

I'm certainly no expert but I would have thought that if you use the appropriate wall lining (Villaboard or whateveer) installed to the manufacturer's specifications, then you shouldn't have a problem. I can't see the need for extra impervious coatings, at least on the walls. The trick that was made known to me was to lay the sheets horizontal so that the sheet fibres were also horizontal and therefore less likely to tolerate rising damp. The big problem, I suspect, are areas where horizontal and vertical joints occur such as wall/floor, wall/ bath,shower and appropriate flashing should be able to deal with this.

[ian]

The bond breaker is a means of providing flexibility at the (typically) right-angle join between the floor and the walls and at internal corners (especially in a shower recess). This is intended to prevent the waterproof membrane cracking due to differential movement between the walls and floor and between adjacent walls. The reinforcing mesh (typically polyester or fibreglass) reinforces the membrane in areas of high stress (at the wall-floor join and between villaboard sheets) arround the openings in the floor.
In the two applications I've done the membrane was painted on using an ordinary paint brush. The intent was to creat a tub that would drain any moisture that got behind the tiles into the floor waste.
The problem with using a tiler or builder is the time required to apply the membrane. Appling 3 coats might only take 2 hrs on each of 3 successive days, but from the tradesman's perspective these are days when they would find it difficult to undertake another job during the balance of the a day so they will either be unwilling to do the job properly or will have to charge for a full day's work even though they only spend about 2 hours at your place. This makes the exercise expensive to you. This in turn can lead to the tradesman trying to confince you that you don't need the membrane - which you don't if your personal ethics will allow you to pass the water problem on to the next owner. If you elect the later route you may want to check what level of waranty owner builders / home owners are assumed to supply to the next owner.