subfloor backer boards

[pete k]

Hi guys/girls,
i have taken up the old flooring and found that the floor is not quite level across the 13m run and wanted to know is it possible to use sand cement to level the backer boards im about to put down as doing it in slc would be financial suicide due to the size, the floor is wood and concrete so was going to use pva primer first, any hints would be great thanks

pete

 

[White Room]

How deep is the floor out

 

[brian c]

a decoupling membrane Ditr matting for example might be an option.When you say not level,do you mean high spots in floor or dips? ..how high and where are they

 

[brian c]

posted same time Mark.Ditto :lol:

 

[pete k]

over the entire 13m its about 10mm , the concrete is a little higher than the wood floor so was thinking of bedding the backerboard onto sand cement to get the level

 

[brian c]

why not use a 9mm ply on the floor(wooden area) then the membrane over the lot

 

[pete k]

decoupling membrane? not sure what that is im affraid

 

[pete k]

when i put the laser on a level line down the 13m run you can see that hall has a fall going away from the back of the house, sorry if im confusing

 

[DHTiling]

Hi pete...As long as the floor is flat ,then that will be fine...use a slc to go from 10mm to feather edge...

 

[doug boardley]

and Pete....don't use pva:yikes::yikes: