Mechanical fixings for hardiebacker on a masonry wall

[bradmole]

Hi, im in the process of doing out or bathroom, we have 2 stud walls and 2 masonry walls, i will be using moisture resistant plasterboard and hardybacker in the shower area.

I have read up about the hardiebacker and they say not to dot and dab it, but to use mechanical fixings and gap filling adhesive. Now i need to pack out the wall by about 20mm to clear pipes and a gap filling adhesive wouldnt get this so i was thinking of batoning part of the wall where the hardiebacker will be then screwing to that (but will only get 20mm of solid fixing), or dot and dab with mechanical fixings to baton or wall (even though they recommend not dot and dabbing)

What would my best options be do you think, also if mechanical fixing, how do you go about doing that and what fixings are best (they say stainless steel) i think id need around 70mm fixings to reach through and into the plugs.

Do i dot and dab wall then let it go off then fix through when set (if so then how do you get wall plugs in) or do i fix plugs first and drive in whilst dot and dab is wet?

Sorry if this sounds confusing i just want to do it right the first time and not have to worry.

Thanks, brad

 

[PrenticeBoyofDerry]

I have DnD cement boards and never had a problem, to mech fix, apply addy to areas that are to be mech fixed, let board/addy set, then drill hole for plug, the plug can then be driven in to wall and screwed (using the screw and slightly screwing in to wall plug, inserting in to pre-drilled hole and tapping the screw head with hammer deals with driving the plug home)

 

[^woody^]

Dab it and then use masonry screws which don't need a plug

 

[bradmole]

awesome thanks guys, i take it it would be a good idea to do this on all dot and dabbed masonry walls as they will be taking quite a weight with tiles etc?

 

[joe-90]

Not if they sit on the floor.

 

[noseall]

Dab it and then use masonry screws which don't need a plug

This how we do it too.

However, it works well with straight boards. If you are trying to dab any boards that are distorted or bent then there will not be enough suction in the board to allow it to pull straight. This is why we use aquapanel because it is rigid, straight and tends not to be distorted.