Watered down PVA on new walls?

[blueharvester]

I'm about to tile the kitchen spashbacks. The walls are newly pastered. I've just finished tiling the utility room splashbacks with the same tiles but a tiler friend has told me that I should've sealed the walls first with watered down PVA, is this correct i.e. should I PVA the kitchen walls before tiling?

Also, on the utility room walls I scored the walls with a sharp object in order to give more grip, was this the right thing to do?

 

[Jasonb]

Most tile adhesive makers do not reccommend the use of PVA but check what it says on the back of your particular brand of adhesive. In most cases you can tile straight onto the plaster.

No need to score the surface either.

Jason

 

[blueharvester]

Most tile adhesive makers do not reccommend the use of PVA but check what it says on the back of your particular brand of adhesive. In most cases you can tile straight onto the plaster.

No need to score the surface either.

Jason

Thanks for this Jasonb, I'll do what you say and check the adhesive.

 

[blueharvester]

Most tile adhesive makers do not reccommend the use of PVA but check what it says on the back of your particular brand of adhesive. In most cases you can tile straight onto the plaster.

No need to score the surface either.

Jason

The adhesive I'm using is made by BAL and the instructions say that a primer is required if the plaster is highly polished. How can I tell if the plaster is highly polished?

If it is highly polished it says to use "BAL BOND SPR" or "BAL PRIME APD", are these the same as PVA?

 

[Jasonb]

If the surface has been heavily troweled it will have a slight sheen or polish.

The SBR looks very much like PVA but will soak into the surface and once dry is water resistant so won't become "live" with the moisture from the adhesive. The APD (which I would tend to use) is an acrylic polimer and looks like liquid laytex.

If you are not a fast tiler the primer will also have the advantage of slowing the drying time of the adhesive so you get a bit more working time, either way don't spread more than you can tile in 10mins.

Jason

 

[blueharvester]

... don't spread more than you can tile in 10mins.
Jason

Oh I didn't realise that you were not supposed to let the primer dry. I thought you apply all of the primer to the entire wall, let it dry, and then start the tiling, and the moisture in the adhesive would then bond to the primer.

 

[Jasonb]

May not have been clear.

Apply primer and let dry.

Only spread enough adhesive that you can fix tiles to in 10mins otherwise it starts to skin over and th etiles won't bond to it.

Jason

 

[blueharvester]

May not have been clear.

Apply primer and let dry.

Only spread enough adhesive that you can fix tiles to in 10mins otherwise it starts to skin over and th etiles won't bond to it.

Jason

I get ya. However, up until now I have been applying the adhesive to the back of the tile not to the wall. Is this wrong?

 

[Moz]

yes ....
very wrong ....plaster the mud/adhesive with the ridged trowel to wall the place tile to wall ..

an never use builder PVA with tile mud/adhesive ....
use "BAL PRIME APD"

 

[Jasonb]

However, up until now I have been applying the adhesive to the back of the tile not to the wall. Is this wrong?

The bond between wall & adhesive will not be as good that way.

Apply a layer of adhesive to the wall with the smooth edge of the trowel as this pushes it well onto the wall, then using the notched side of the trowel rake out the adhesive. Push the tile into the adhesive with a slight twisting motion to make sure it gets a goodbond.

Jason

 

[blueharvester]

The bond between wall & adhesive will not be as good that way.

Ok I see. However, as I said, I've done it that way in the utility room i.e. put adhesive onto tiles first, and the bond seems to be very good. But does this mean that there is a chance that the tiles will fall off in years to come?

 

[gcol]

For what it's worth, any problem I've had with adhesive failing has been in it adhering to the tile, not the wall. So if you've applied it to the tile, don't worry - we all need to do that at times anyway. And before you say, "I left the adhesive on the wall too long before applying the tiles", I didn't. Faulty adhesive, but it showed on the adhesive/tile bond - the adhesive/wall bond was ok. What I'm saying is that your tiles should be ok. Reading this through, it's not too clear but I can't be ar$ed changing it now.