Warped backer board | warped no more ply after priming!

[SteUK]

Evening all, me again!

Just primed (3 to 1 sbr) one side of a sheet of my backer board in preparation for putting some up tomorrow and it has warped! I can press it flat to the wall but it has me concerned. How much warp is too much? Is this normal?

Thanks!

 

[Dave]

What backer board ?

 

[SteUK]

6mm No more ply (for my uneducated sins)

 

[Dave]

Soooo, why did you prime it ?

 

[Dave]

Just checked NMP website , for complete waterproofing prime with SBR 3:1 lol lol.... Nah!!!!!!!



As for your question , the screws will flatten it out .

 

[SteUK]

Hehe. Yeah. They say prime both sides with 3 to 1 mix of sbr.

Even with my diy knowledge I laughed when I read that. Don't worry, I have a mapei tanking kit for around the bath (and over shower) area 😉

It's probably only warped 5mm on the short end and 10mm on the long edge. I was going to put it up with adhesive then screw down when set. Guess I will have to kind of level it out with screws before the adhesive sets. But be careful not to go mad with the driver!

 

[judge]

Hi ste,Im pretty sure 6 mm is flooring grade.(never used it ) with hardi its 6 for floors and 12 on the walls

 

[SteUK]

Hi judge,

Thanks for the input!

Manufacturers say their 6mm is fine for walls. Though they say dot and dab is how to fix to solid walls, which I cannot get on board with...so putting down a full bed of adhesive and mechanically fixing as per instruction as well.

 

[Rizzle from the Portizzle]

so this board does not like water on one side only reminds me of a sponge .the water resistant a great get out always read the small print if you go to b&q you will find water proof bucket adhesive read the small print water resistant .shame on mapie so when do they put the truth in big letters

 

[White Room]

so this board does not like water on one side only reminds me of a sponge .the water resistant a great get out always read the small print if you go to b&q you will find water proof bucket adhesive read the small print water resistant .shame on mapie so when do they put the truth in big letters

Your'd then read it Ray.....

 

[Rizzle from the Portizzle]

Your'd then read it Ray.....

i own i huge magnefying glass can take up to four strong tilers to lift you need one more to look through with a telescope and wright down what they see 😱

 

[Just Rizzle]

so your going to install some moisture resistance board then tank it out .the board is a mear 6mm thick wouldnt you better off in my opinion plaster boarding with 12 mm plasterboard and tank that out your going to get the same result or are you the plaster board is twice as thick so should be less flexable. as far as I was aware no more ply is more for floors than walls.
I would plaster board and cover with kerdi membrain

 

[Dave]

I assumed it was for the floor .?

I'm with Ray on this one.

 

[SteUK]

I am never one to usually go against advice of those with more knowledge and experience than me, but in this case all the materials have been bought and advice taken from the manufacturers, who say it's fine in all their literature and back it with lifetime guarantee!

Got 4 boards up now...and I have another question regards tanking! (Sorry!)

Should I be taping over all the washers/screws as well as corners? Should I tape the board to the bath?

Thanks!

 

[Dan]

With the tanking tape? Bath yes. Screws won't hurt but no not usually.

 

[SteUK]

Thanks Dan!

Is the procedure from board to bath...

- silicon gap between board and bath.

- masking tape along bath with gap from board less than tile+adhesive.

- waterproofer, tape, waterproofer.

- tile

- Cut just inside masking tape with sharp knife.

- Silicon the gap from tile to bath.

?

 

[Dan]

Use a tile thickness and a pencil to mark a line down the bath. Put tanking tape up to that line. Tank everything.

Tiles with adhesive then will come over that line.

Grout as normal.

Then small Silicon bead in corner and to bath. Use masking tape for that if you're not comfortable getting it spot on without.

 

[SteUK]

😀

Thanks Dan!

 

[Dan]

Any time.