Hardiebacker Board - Which Adhesive

[AdamW]

Evening all,

Ive just ordered hardiebacker board to install in bathroom.
Wall - Will be installed directly onto existing masonry
Floor - Will be installed on to 18mm WBP, with a further sub floor of 18mm WBP beneath.

I have read conflicting information with regards to which adhesive is best used. James Hardie recommend on their site non-flexible adhesive for the floor, and a high strength cartridge adhesive + mechanical fastener for the walls.

However, reading various forums online people have suggested normal plasterboard adhesive for walls or flexible tile adhesive, and flexible tile adhesive for the floor.

In my mind non-flexible tile adhesive is best for the floor, as it ensure the boards can not move (despite the fact I have a very rigid floor underneath the hardiebacker). For the wall I would have thought the same theory applies.

• Flexible or non-flexible tile adhesive for the floor?
• Cartridge adhesive or flexible/non-flexible tile adhesive for the walls (I will use mechanical fastener with chosen adhesive too)

Many thanks in advance for any help you can give.

 

[Stef]

I always use a flex addy but as you say you don't have to as Hardie state.
It sits better in my head that you are fixing to timber so a flex addy must be used.
I've been fixing Hardie for years without problem so I will keep fixing this way..

 

[Dave]

When fixing to floors , then the adhesive is to only to take up undulations in the substrate and you screw into place , so a standard adhesive will suffice but most are polymor modified these days for bonding to porcelain .
You mention nine flexi so the boards don't move , only an elastomeric adhesive will deform as you suggest , so using say an S1 will still be fine IMHO .

 

[AdamW]

Hi thanks for the replies.

Are you suggesting to mechanically fix the floor boarding too? The floor is very rigid, so I would expect non-flexible to be ok, but maybe non flexible is better? Are you able to suggest a good non flexible adhesive?


Ref the wall, they have come back to me and said as long as mechanically fixed, D&D is actually ok. They just don't advertise as such as people may only D&D with no mechanical fix.

 

[rj1884]

As mentioned the adhesive is to fill and voids etc and the boards are then screwed down as well

 

[Lodger]

Hi,

I have dot and dabbed Hardiebacker Board for a bathroom using board adhesive then when "completely" dry, use Marmox fixing dowels to mechanically fix them back.
just mark where the adhesive is applied to the face of the backer board so you can mechanically fix right above the adhesive areas.
Always prime the walls and I personally would prime the back of the tile backer boards so they don't come away from the wall when hammer drilling.
Always over do it I say!!

 

[AdamW]

Hi all,

I am finally getting round to fixing the hardiebacker board to the masonry wall now its all been tidied up. I have the adhesive and the mechanical fixings, and some Cementone SBR for priming.

Couple of questions about the application of the SBR.

- Is it applied as-is direct to the wall? Or does it need to be mixed with anything (Back of packaging has applications for bonding slurry, floor toppings/screeds & external waterproof renders listed which all require sand/cement etc)

- Is it applied and allowed to dry, before then installing the hardiebacker with the adhesive/screws?

- Worth priming backside of Hardiebacker before application or not?

Many thanks in advance for the help!

 

[AdamW]

Any advice guys on the SBR primer questions above?