Hardie Backer Board Or Plywood Substrate

[DazJWood]

I am in the process of doing my bathroom. (Actually I have been since February but that's another story ). I have bought marble floor tiles and the plan was to lay these on a plywood base. The floorboards currently in the bathroom are of the 18mm chipboard variety but unfortunately a number of them are water damaged. The one under the bath was completely sodden so I have already ripped that one out. After researching this forum and a number of others on the net I had come to the conclusion that the ideal solution would be to take up all the chipboard flooring and replace this with WBP 22mm plywood and tile over the top.

I am now wondering about the use of Hardie Backer board. I've read through their leaflet and this seems like another ideal solution. I could replace the damaged chipboard flooring with the same and then go over the top with hardie backer board.

Does anyone have any comments, preferences on either solution?

The hardie cement board is only 6mm thick. Is this a sufficient thickness to tile over to avoid movement?

Thanks in advance,

Daz

PS. I'm no expert diyer so go easy on me if I've suggested a wrong idea :dizzy2:

 

[jay]

hi and :welcome:yes you could go with chipboard but as you have already seen it not the best once wet its stuffed best to replace with ply and then cement sheet have you sorted the leakes first it might be worth your while to waterproof floor and be done with it hope this helps:8:

 

[Bartlett]

Agree with above. Best get rid of the old floor now and do a thorough job. You might also want to add extra noggins to add a bit of support while you're at it. Definitely worth doing.
Are there any height issues? ie, at the doorway into the landing/next room? The backer board is thinner which may be better for you. Plenty of advice available on this forum (just search) about how to use this.

 

[doug boardley]

wbp plywood will suffice if you make sure you have plenty of noggins between the floor joists. I'd screw it down at 200mm centres. I'd also be tempted to use a waterproofing membrane such as durabase wp, here's a link
[ame=http://www.youtube.com/watch?v=pigKorqimGk]YouTube - Durabase wp wet room tanking membrane dura-wp[/ame]

 

[doug boardley]

I've edited my post, I'd stated "decoupling" when I meant "waterproofing" membrane

 

[DazJWood]

Hey thanks guys for all your quick responses! Much appreciated.

I'm still a bit unsure of which route to take though.

I've bought some of the homelux membrane to do my shower cubicle walls and above the bath. I wasn't going to put anything down for the floor though. (Plus how does it waterproof the floor if there are numerous holes for wastes and pipes).

The height between rooms should not be too much of a problem as long as I don't increase height too much. The marble tiles I have got are fairly thick though so I'd rather try and avoid raising the floor too much. Nevertheless I want the job to be the best it can be.

I'm still confused over what options I've got because it seems I have a few more lol. (Maybe I just need to stop dithering and just go for one!)

1) Should I remove existing chipboarding completely and then replace with 22mm ply and tile over.

2) Remove existing chipboard floorboard, replace with 18mm WBP ply and then fit hardie 6mm backerboards and then tile over.

3) Leave good chipboarding and replace water damaged ones with the same new ones. Then fit Hardie 6mm backer board and tile over.

4) Then I guess there is all of the above with the addition of a membrane (Homelux or the other membrane Doug above mentioned).

Thanks again for all your comments (and thanks for excusing my ignorance to all this )

Daz

 

[jay]

hi deffo remove chipboard option 2 completly screwed down with membrane would be my choice :8:

 

[DazJWood]

Thanks Jay,

While I'm on the subject of Hardie backer board and Homelux membrane: I was planning on using the Homelux matting onto plasterboard for my shower cubicle. Would I be better using Hardie backerboard (instead of plasterboard) and then Homelux membrane over the top for this application as well?

Thanks,

Daz

 

[jay]

yes as cement sheet will outlast plaster and carry more weight make sure you seal tap stems to surrounding walls so no water gets in :8:

 

[DazJWood]

Great thanks! What is the best way to seal the tap stems? (that does mean where the pipes come through doesn't it?).

 

[DazJWood]

I've bought Excel Bond Rapid Flex Adhesive for the marble floor tiles. Is this adhesive the correct stuff for going onto 6mm Hardie Board? When I bought the tiles I told the guy I was putting them down on at least 18mm plywood and he suggested this adhesive saying anything less than 18mm he'd recommend something different. As the Hardie board is only 6mm thick will this make a difference to using this adhesive?

Thanks,

Daz

 

[jay]

hi cut holes around taps fairly neat then use a paintable silicone to seal before waterproofing not sure on adh never used that brand just make sure its compatable with waterproofing:8:

 

[White Room]

Use white adhesive for light coloured marble and grey adhesive for dark marble, give the tiles a back skim on the rear of the tile to avoid any bleeding through

 

[DazJWood]

What does back skim mean? and with what?

 

[White Room]

With the adhesive your using a white or grey, a thin layer applied with the flat part of a trowel to the rear of a tile

 

[DazJWood]

Right I've now got rid of all my old flooring. Installed loads of extra noggins for support, installed a security light and a double socket (in my adjoining room and it's nothing to do with the bathroom but while I had the floor up I thought I may as well! :8.

I'll be putting the new flooring down soon, which will be 18mm ply (sealed with Bal SBR) and then I'm going to put Hardie Backer Board over the top and then marble tiles.

This may seem a stupid question (which I'm sure it is!) but do I need to use any particular screws? Im guessing for the ply I can just use any type of decent woodscrew? For the Hardie boards there are specific Hardie screws. Should I get some of those or can I use an equivalent? Are they just the manufacturer charging a premium because they can?

I guess I'm asking because I'm worried about using screws that may rust and leach into the marble.

Thanks,

Daz

 

[Dan]

Does it void warranty if you use other screw makes? You I'm pretty sure it's just screws that don't get damaged by water over time, though I could be wrong.

 

[Aston]

as long as they are classed as 'corrosive resistant' or 'corrosive resistant coated' then i dont think you will have any issues ..

hope this helps

 

[jay]

as above also the w/p over the top should reduce chances of rust:8:

 

[DazJWood]

as above also the w/p over the top should reduce chances of rust:8:

Excuse me for being thick but what's w/p? Are you refering to the Hardie backer board I'm putting down? This needs to be screwed down as well.

Thanks,

Daz

 

[jay]

hi sorry w/p -water proofing .membraine its standard over here in all bathroom floors to waterproof .it saves timber floors from water damage i dont think its compulsery over there but it will give you peace of mind if you do it and hardie backer board is best glued and screwed hope this helps:8: