Should Hardiebacker boards be used or not?

[jason67]

Hi All

I’ve just had a loft conversion with one of the rooms being a bathroom. The floor is P5 grade (the green tinted moisture resistant stuff) 22mm chipboard and has been layed absolutely flat. The walls are skimmed plasterboard.

I would like both floor and walls tiled but it's the floor I'm concerned about. I’m using Wickes ceramic Tiles 33x33cm (8mm thick) for the floor.

I’ve bought Hardibacker boards to lay on the floor, but havn’t fitted them yet as I was hoping my tiler would quote for this job along with the tiling. Would it be reasonable to assume that laying Hardibacker boards is a job that a tiler would undertake?

I had an experienced tiler come to give me a quote yesterday but was surprised to hear him say that I don’t need Hardibacker boards. He said that he uses a special rubber based adhesive to fix the tiles directly to the P5 chipboard flooring. I’m a little concerned that this is not the correct fixing method and that Hardibacker boards should be used.

Could anyone give me a little advice on this?

 

[Ian]

Should Hardibacker boards be used or not?

100% use the hardie boards. To suggest tiling straight to the chipboard is ridiculous. And yes, fitting the hardies is all in a tilers prep work.

 

[JamesHardie]

HardieBacker is a Cement based board that provides a suitable surface to tile on to. Unlike wood, it does not expand and contract with exposure to water. Attached is a copy of the HardieBacker installation instructions.

If you are looking for an additional document to source take a look at this NHBC Standards – Section 8, Part 3, Para D4

TILES ON WOOD-BASED SUBSTRATE
The floor should be designed to take the additional loads of tiles and any other materials (e.g. overlays). Tiles should be suitable for laying over a timber base.
The floor decking should be: chipboard floor decking overlaid with minimum 10mm plywood suitable for exterior conditions and fixed as above, or proprietary separating/de-coupling layers, tile backer boards or tile bedding reinforcement sheets used in accordance with the manufacturer's recommendations.

I hope this helps

 

[Gazzer]

Can someone explain this,

"Apply a gap filling bed of non-flexible tile adhesive to the subfloor using a 6mm notched trowel."

 

[Peter]

Interested in that too, surely it'd break down and crumble over time?

 

[White Room]

I'll stick to using spf.....

 

[JamesHardie]

HardieBacker is fastened to the subfloor with nails or screws, not exactly with the adhesive. The intent of the cement based adhesive is not to make the board stick to the subfloor, but rather to be used as merely a gap filler to minimize the imperfections of the floor. The installation system has been rigously tested and HardieBacker performs best when all of the steps in the installation guide are followed.

 

[White Room]

HardieBacker is fastened to the subfloor with nails or screws, not exactly with the adhesive. The intent of the cement based adhesive is not to make the board stick to the subfloor, but rather to be used as merely a gap filler to minimize the imperfections of the floor. The installation system has been rigously tested and HardieBacker performs best when all of the steps in the installation guide are followed.

Surprised of the use of nails though.....

 

[jimthetiler]

What ever you put on a wooden floor,its still a wooden floor and will flex and move and expand and shrink with the building.Tell your tiler he can still use his rubber adhesive once he has laid the backing boards that way you will have a fighting chance of the floor lasting a while,and another thing ,the smaller the tiles the better.

 

[jason67]

Thanks gentlemen for you advice.

Sounds like the Hardibacker boards should be used.

One thing I’m a little confused by; The Hardibacker instructions state “Apply a gap filling bed of non-flexible tile adhesive to the subfloor using a 6mm notched trowel.” Does this mean, in my case, that the non-flexible tile adhesive should be applied direct to the P5 chipboard flooring?

If it does, then I don’t understand why you can’t apply flexible adhesive directly to the P5 chipboard flooring and fix the tiles directly to the P5 chipboard flooring?