Hardibacker

[Rad2474]

I've got a small floor area to tile for my daughter.The floor is weroc but she dosen't want the edge to high by using ply.(it's a kitchen diner area) So i suggested 6mm hardibacker but i've never fitted this before so what's the best way to fit it. Thnx Paul.

[figaro]

I've got a small floor area to tile for my daughter.The floor is weroc but she dosen't want the edge to high by using ply.(it's a kitchen diner area) So i suggested 6mm hardibacker but i've never fitted this before so what's the best way to fit it. Thnx Paul.

Probably be easier to convince her to have a bit of vinyl lay instead

[kilty55]

hi mate,,ive only ever fixed hardibacker to walls and just use screws/washers to hold it tight in place same as ply

[Dave]

Hi paul mate.....it's not a floating floor is it..?

If not then make sure it is screwed down well and then use Mapei keraquick and latex plus.....use a 4mm trowel and stick the hardi 250(6mm) down with that....Use suitable screws fixed about every 200mm and 50mm in from the edges...

Then you are set to go...

Follow the directions for mixing the powder and latex...

[oogabooga]

The old Hardi seems to have varied fixing instructions throughout the world. NZ is fixings at 75mm centres around the perimeter and 150 mm through the field of the board. And you can go as close as 15mm to the edge, but stay 50mm away from the corners (to prevent corners breaking off).

Good to see you guys put addy under the board, not doing so results in a lot of floor failures.

[Dave]

Hardi 250 fixing instructions...


https://www.pureadhesion.co.uk/store...structions.pdf

[doug boardley]

you don't have to use keraquick annd latex plus tho' do you Dave? as I normally just use a spf (normally onto weyroc/ply floors)

[Dave]

Keraquick will cope on its own doug.....but as it's paul.. i wanted him to make sure his daughter didnt kill him if it goes wrong...

[mart08]

I find the hardie screws a load of rubbish so i use an alternative. A good flexi rapid set and screw down every 200 and 50 from edges.

[aflemi]

just had 1st day of 2-week PTS Harlow training course. We covered floor substrates and only ply was mentioned. I asked if backerboard could be used in place of ply to keep height down and was told no, ntg better than ply.
I appreciate backerboard does not add strength/rigidity to a wooden suspended floor, in what circumstances would you use it and is it widely used?

[Dave]

Cement boards like hardi can add strength to a floor.....if fixed correctly...A certain adhesive company sez not but they would... and Mapei say they their adhesives are suitable.....

[aflemi]

So on a well fixed boarded sub-floor you could use 6mm hardi in place of 12mm ply (i know BS is 15 but no-one seems to follow that)??

[whitebeam]

I do and have had no problems with 6mm on floors

[oogabooga]

Guess it depends what you mean by strengthening the floor. I suspect Hardi would decrease deflection between joists, but don't see how it would help deflection along the length of the joist span. Just an opinion though, not aware of any such testing.

[Dave]

The thing is in the uk...we do not get that long enough run of joist to deflect enough to cause concern.....

I have noticed on the JB forum that joist flexing does seem to be an issue...

[oogabooga]

Yep, most of the UK construction is a bit different to down under or the US, where timber framing in the norm. Had to beef up many a floor in my area to deal with deflection. Just pointing it out is all

[Rob Z]

We've had to add a lot of plywood and scab on joists, as well. Oh well, it's money.

Rob, are most houses in NZ and Australia stick-framed the way they are here?

[oogabooga]

Rob Z, yep similar construction techniques from what I can tell, although I notice in residential dwellings you guys don't have any nogs/dwangs (horizontal members) in your wall framing.

It's funny but when we get visitors from the UK or Europe, they tend to remark about the construction being similar to the US and that our television programming is full of US shows. I'm never sure whether they're meaning that as a putdown or simply an observation, as most Europeans I've met are really, really square! (not brits)

[Rob Z]

Hi Rob,

The horizontal members in the stud cavities are called fire blocking here, and generally (in some markets) they are not installed as long as the holes in the plates are filled with rock wool or some other material to act as a draftstopper (as per the fire code). The fireblocking was standard in almost all houses I have worked in up through the 80's....sometime after that time it seems that the practice dropped off.

I hear and read all the comments about how things are built in the US, and my observation is that there is so much variety over the 50 states and for 300+ million people that it is impossible to generalize about anything. Some standard practices are very good, others are so-so, and some are mass-market driven crap. It is the latter stuff that ensures that we have good remodeling work to do.

Most of the TV shows that I have seen are insipid, and don't really reflect reality (I know that you know this). Some of the stuff I see on them makes me .

[oogabooga]

Yep, pretty much figured (from years of the JB forum) that there's a great deal of variety in construction techniques in the US. Even in a tiny country like NZ it's funny how various regions will have there own way of doing things, or different interpretation of codes and regulations.

[Consett John]

just had 1st day of 2-week PTS Harlow training course. We covered floor substrates and only ply was mentioned. I asked if backerboard could be used in place of ply to keep height down and was told no, ntg better than ply.
I appreciate backerboard does not add strength/rigidity to a wooden suspended floor, in what circumstances would you use it and is it widely used?

I have just used hardi backer in an en suite due to the fact that any water ingress would not result in the tiles lifting also can be used on kitchen floors as a failsafe against washing machine leaks