Correct adhesive for backer boards and porcelain

[Rolandk]

Hi,
just been checking on adhesives and a bit confused!
I have a concrete substrate (coarse and lumpy and the more I sweep it the more loose material it releases!) Also need to tile over a small amout of green chipboard. Electric UFH going in too. Plan is to SBR prime the concrete then board over the concrete and chipboard with 6mm Marmox boards. What is the best adhesive to use to stick the boards down to the 2 different substrates? I was going to screw down to the chipboard as well. Then the correct adhesive for porcelain (300mm x 600mm) tiles onto the Marmox? Total area around 30 sq m.

Was going to get Mapei products?

Thanks,
Roland

 

[Rich]

Mapei are very good. If you go with Mapei, I would use their primer/grout/silicone as well. Wher the concrete joins the chipboard, you will need to leave an expansion joint in the boards and in the tiles.

You will need a single part rapid adhesive, do you have a Tile Giant near you? If so pop in there and they will give you the right adhesive.

When you come to the chipboard, you must make sure that it is fixed down properly, if there is and bounce in the boards this must be sorted out before you over board. Then the cement boards need to be stuck down and screwed down into the chipboard.

 

[Rich]

I have just noticed your total area, you may have to use more expansion joints. You should use an expansion joint in an unbroken run of tiling up to a max 10m and you can pretty much half that for a floor with under floor heating.

 

[Rolandk]

Thanks for the info Rich,

Although the total area is quite large it's made up of a number of smaller areas but I'll bear in mind the 5m limit for expansion joints, should be easy enough to put them at doorway thresholds. Out of the Mapei range which particular primer and adhesive would you recommend. Good idea to get their grout and silicone as well as the colours will match better I guess.

Cheers

 

[Rich]

I would use Primer G and then Keraquick.

All instructions are on the bottle/bag

 

[Rolandk]

That's great thanks,
I'll get down to Tile Giant and sort it out. Hell this stuff is expensive isn't it? Cost as much to stick the tiles down as to buy them!! Appreciate the help,

Roland

 

[Daz]

Are you planning to tile directly over the 'lectric UFH or will you be applying a self leveller?
My recommendation would be to slc as this will encase the wires and eliminate any potential hotspots. It will, also, provide a nice smooth tile surface and make the floor more rigid so worthy of consideration.

With regards to cost, if you use cheap now it is likely that you will not be pleased with the results and you run a massive risk of longer term failure. Why should the fixing costs be any less than the cost of tiles, I'm confused?

 

[Rolandk]

Hi Daz,
thanks for the advice. I am undecided as to whether to use SLC. I am already adding more height to the floor than I wanted to as it needs to meet up with other floors and I expect the height difference to be around 20mm as it is. I just figured SLC plus the addy would add another 3-5mm? Mind you I hear what you are saying and I might go for the SLC after all.
I don't want to skimp on materials and do intend to use the Mapei stuff and Marmox boards, I was just surprised that all this will come to more than the tiles!! I'm sure a lot of people don't realise this when they get quotes for work and think it's mainly labour.
You only get what you pay for!

Cheers,
Roland

 

[Tats]

Minimum thickness for overlaying timber floors is 10mm when using a standard SPF addy like keraquick

 

[Rolandk]

Hi all,

just when I thought it was all sorted the other half says she's not keen on any expansion joints and wants a 'continuous' look!

Told her we have to have expansion gap where transition from concrete to timber substrates. As far as the rest is concerned the longest continuous length of tile over the concrete will be 8 metres. This passes thru 2 doorways where she doesn't want the expansion joints. Am I pushing my luck at 8 meters with no expansion joints and UFH on Marmox?

Thanks,
Roland

 

[Tats]

Yes you are, go for a sift movement joint ie silicone the same colour as your grout this blends in better and if well done you won't notice it very much

 

[Mike]

mapei have matching grout and silicon, i.e. the same code number, i did the silver grey a few weeks ago, i think it was 111

 

[Rolandk]

That's great guys, thanks. So I can plan the best place to put the joint what is the max tile run I should do before the joint needs to go in?

Cheers,
Roland

 

[Tats]

I'd go 5 m or nearest whole tile and put joint in there. Make sure that where the silicone goes is free from addy at that point should be just the screed showing so clean all addy out let dry then silicone at the end

 

[Rolandk]

Ok will do thanks,

Roland