Hardiebacker only screwed to chipboard. No adhesive

[leothetiler]

Hi,

I went to look at a job today, and the homeowner is a keen DIYer. He has been renovating the bathroom. Old tiles removed which were stuck directly on chipboard and hardibacker screwed down. 6mm board over a particularly lumpy floor from the old adhesive, but board not stuck down at all just screwed.

I am worried about the air pockets under the board. The new tiles are large porcelain. Should I tell the homeowner to take up the boards again? Or would the addition of ditra onto the backerboard make it a sound surface to tile? Your advice would be appreciated.

 

[beanz]

They've got to come up mate.

 

[White Room]

A above....

 

[Ian]

Yep, fit them properly or you're likely to get a failure.

 

[Stef]

Lift the Hardie & scrape that floor as flat as you can get it then glue & screw the Hardie back down.
If needed slc if its still not flat.

 

[Dougs Third Go]

as all above, glued and screwed is the only way to go.

 

[prceramics]

i have been to a fail where the hardi was only screwed down with no addy

 

[JamesHardie]

Hi Leo-

The first step in installing Hardiebacker to the subfloor is to make sure you have a structurally sound subfloor that is not damaged, loose, warped, uneven, and that it has a clean and flat surface. Your concern about the airpockets is a valid one. You must lay the backerboard into a bed of tile adhesive, it is essentially used as that gap filler. Using a bed of adhesive is industry standard when installing a cement board, and we cannot warrant the board without.

I'm including a link to our website where you can download the installation guide as reference, or perhaps it will help you when you go back to the homeowner. JamesHardie | HardieBacker® EZ GRID® 6mm for Floors

Hope this helps!

 

[Mr Tiler]

Hi Leo-

The first step in installing Hardiebacker to the subfloor is to make sure you have a structurally sound subfloor that is not damaged, loose, warped, uneven, and that it has a clean and flat surface. Your concern about the airpockets is a valid one. You must lay the backerboard into a bed of tile adhesive, it is essentially used as that gap filler. Using a bed of adhesive is industry standard when installing a cement board, and we cannot warrant the board without.

I'm including a link to our website where you can download the installation guide as reference, or perhaps it will help you when you go back to the homeowner. JamesHardie | HardieBacker® EZ GRID® 6mm for Floors

Hope this helps!

is it the actual 'air' in that cheeky little pocket underneath the board that is the problem or is it just the fact that there is a void underneath which could result in bouncing movement which will eventually cause the tile/s in that area to come loose? thanks

 

[JamesHardie]

Yes, I would agree with your statement. We call the adhesive layer a gap filling bed of adhesive, and it can be flexible or non-flexible. The purpose isn't to make the board stick, it's to fill the gaps or voids between the subfloor and the backer.

 

[Mr Tiler]

Yes, I would agree with your statement. We call the adhesive layer a gap filling bed of adhesive, and it can be flexible or non-flexible. The purpose isn't to make the board stick, it's to fill the gaps or voids between the subfloor and the backer.

brill mate that's exactly how I think of it. cheers

 

[Rookery]

Yes, I would agree with your statement. We call the adhesive layer a gap filling bed of adhesive, and it can be flexible or non-flexible. The purpose isn't to make the board stick, it's to fill the gaps or voids between the subfloor and the backer.

I've always used this method to fix Hardie but have sometimes wondered if, when boarding a perfectly flat chipboard floor, why use adhesive as there are no gaps to fill?

 

[Mr Tiler]

I've always used this method to fix Hardie but have sometimes wondered if, when boarding a perfectly flat chipboard floor, why use adhesive as there are no gaps to fill?

in my opinion if a floor is perfectly flat just use a smaller trowel size at least as it surely helps to glue and screw rather than just screw

 

[Herbis]

Yes, I would agree with your statement. We call the adhesive layer a gap filling bed of adhesive, and it can be flexible or non-flexible. The purpose isn't to make the board stick, it's to fill the gaps or voids between the subfloor and the backer.

Sorry to revive a (very) old thread, but I can't seem to find an answer for my question anywhere online - including by contacting James Hardie Support - so hoping you can help?

I have a P5 chipboard floor and 6mm hardie backer to go over it. There are seemingly no options to apply tile adhesive on to the P5 - no manufacturer recommends their product is used in this way, even with primers. How, therefore, is it possible to apply a bed of tile adhesive when going over P5 chipboard? Is it sufficient to use a grab adhesive instead?

Thanks!