Fixings for hardie backer to masonry (concrete) wall

[markharro]

I think I need something like this - https://www.fischer.co.uk/en-gb/products/frame-fixings/hammerfix-n/hammerfix-n-s-d but will the washer be an issue when we come to tile? Is this sort of thing better - https://www.fischer.co.uk/en-gb/products/frame-fixings/hammerfix-n/hammerfix-n-p - although again the plastic sleeve head will stand proud of the board. 

 

Maybe this - https://www.fischer.co.uk/en-gb/products/frame-fixings/hammerfix-n/hammerfix-n-s ?

[Mr Punter]

You may find it easier to use Wedi / Marmox type board as it is much lighter and easier to cut and fix.

[markharro]

Thanks but I have already got the Hardie board and fitted half of it to studwork - just got this tricky bit over about 1m2 of bowed concrete to sort out!

[Russell griffiths]

Can you not dot n dab it with flexible tile adhesive 

then when it’s gone off screw it up with any type of galvanised screw and plug. 

[Alan Ambrose]

Concrete screws or old fashioned wall plugs?

[markharro]

Thanks @Russell griffiths and @Alan Ambrose here is where I have got to so far. Next step to screw the board to the concrete. I have the fixings in the photo - the SS screws are 50mm. Will these be long enough? Also how many screws and what pattern for this section of board which is 800mm high by 900mm wide? thanks,

[markharro]

Is anyone able to comment on my post above?

 

[Russell griffiths]

Roughly every 200mm

you can go 150 around the perimeter, but if it’s well stuck on thats ott, every 300 would still be ok. 
are you boarding over that timber ?
if so I would have boarded that first to make sure your lower wall is in line. 

[markharro]

Thanks @Russell griffiths thats helpful. What about the screw length though - would 50mm be enough?

 

Yes boarding up over the timber. I see what you mean about starting there and working down.....next time I will know better. I have planed the studs so that an 18mm ply spacer should level the board with the one below - hopefully!