Hardie backer boards

[charlie1]

Having recieved conflicting fitting guidlines from hardies tech dept i decided to call them up again. There answer re fitting 6 mm boards to timber subfloor, Should be glued and screwed, but IF excessive bounce in floor then this has to be addressed first! I asked him to define excessive bounce but he could not. Can any of you guys give me the definative answer to an excesively bouncy floor because in my experience there is always movement in a timber floor!

 

[DHTiling]

Only the installer can decide is deflection is excessive, this IMO is moving floor boards or floors that deflect when waled across etc etc... some peeps do the glass of water test but experience tells you what you can and cannot tile.

 

[beanz]

I'm not convinced that the glass of water test actually works. I've yet to see a timber floor you could jump on, and not get movement in the water!?!

 

[The D]

My stance on it is if there are loos boards or if the boards are fixed with only nails. if the floor creaks when you walk on it or if you can make the water spill over the edge of a glass when you walk on the floor then there is to much bounce.

 

[charlie1]

Lets face it, all timber floors have slight movement, what im trying to get at is, this seems to be a total get out for hardie. What if a floor fails, they can just say must have been too much movement in the floor! Must admit, i like using the boards but this does concern me!

 

[Dougs Third Go]

but hardie don't claim to eradicate deflection, it's just a substrate to tile onto, so it's not their concern tbh. If there's too much deflection in a timber floor it needs sorting before you put the hardie down.

 

[Rookery]

Yes all manufacturers will find a get-out and in their eyes its usually fixer error. Trouble is, it usually is fixer error by those who dont know or dont care enough to get it right first time.
Its difficult to measure bounce. To justify me over-boarding with Hardie, I show the customer how much bounce there is by putting my pendulum laser on the floor and walking (Not jumping) around and they can see the beam bouncing up n down. Most customers can understand that a rigid tile glued down wont bend and therefore thats why they're paying the extra to get the job done right.
I think there is a calculation for measuring the deflection, its something like: joist span divided by 360 equals allowable deflection. So therefore a joist span of 450mm will have an allowable deflection of 1.25mm. Christ knows how you'd measure it though. It may not even be true, I might have imagined it. At the end of the day the fixer has to make the call.

 

[The D]

I am loosing the will to live ( You do not fit hardi to solve a bounce problem you sort the problem then fit the hardi )

 

[Andy Allen]

why would hardie need a get out clause...? they provide a decent surface to tile to, its up to the experience of the fixer to prep the floor, if you dont know whats suitable to tile to, then imo you shouldn't be doing the job, as it will be nothing but guess work...

 

[Peter]

If a floor isn't too bad to start with, I find that the Hardie will stiffen it up nicely, even though it's not meant to be for that purpose. Agree that a bad floor needs sorting first though.

 

[charlie1]

why would hardie need a get out clause...? they provide a decent surface to tile to, its up to the experience of the fixer to prep the floor, if you dont know whats suitable to tile to, then imo you shouldn't be doing the job, as it will be nothing but guess work...

Hardie claims there boards can be used instead of plywood. The only reason i use ply is to stiffen up a wooden floor so to me they are claiming there boards will stiffen up a wooden floor sufficiently to tile too. If they dont have and anti flexing properties then whats the point in using them? Ply can be tiled to no problem.

 

[Dougs Third Go]

Hardie claims there boards can be used instead of plywood. The only reason i use ply is to stiffen up a wooden floor so to me they are claiming there boards will stiffen up a wooden floor sufficiently to tile too. If they dont have and anti flexing properties then whats the point in using them? Ply can be tiled to no problem.

but you still wouldn't tile a ply-wooded floor that had deflection, well I wouldn't anyway.

 

[charlie1]

but you still wouldn't tile a ply-wooded floor that had deflection, well I wouldn't anyway.

As i said, imo, there is always a degree of deflection in a wooden floor.

 

[The Legend; Phil Hobson RIP]

Yes all manufacturers will find a get-out and in their eyes its usually fixer error. Trouble is, it usually is fixer error by those who dont know or dont care enough to get it right first time.
Its difficult to measure bounce. To justify me over-boarding with Hardie, I show the customer how much bounce there is by putting my pendulum laser on the floor and walking (Not jumping) around and they can see the beam bouncing up n down. Most customers can understand that a rigid tile glued down wont bend and therefore thats why they're paying the extra to get the job done right.
I think there is a calculation for measuring the deflection, its something like: joist span divided by 360 equals allowable deflection. So therefore a joist span of 450mm will have an allowable deflection of 1.25mm. Christ knows how you'd measure it though. It may not even be true, I might have imagined it. At the end of the day the fixer has to make the call.

This is exactly how I check for deflection, I set my self leveling laser on a tripod, and then walk around the room. It works for me, I do believe that Hardie board glued and screwed does improve rigidity on a wooden floor. I have done the same test with the laser after boarding, and seen a vast iimprovement. But as above the floor should be braced prior to boarding.

 

[The D]

Hardie claims there boards can be used instead of plywood. The only reason i use ply is to stiffen up a wooden floor so to me they are claiming there boards will stiffen up a wooden floor sufficiently to tile too. If they dont have and anti flexing properties then whats the point in using them? Ply can be tiled to no problem.

Hardie backer boards will not swell or contract with the changes in temperature and moisture content in the air they will remain stable even when submerged in water they do not rot they do not promote the growth of black mold and they make a perfect sub-straight to receive tiles.
I think this is the point you are missing. If you are using this type of board to strengthen a floor then you are misusing them and if there is ever a problem with your floor there is only one outcome, incorrect use of the product and that IS fixer error not a get out for the manufacturers.

 

[charlie1]

I'm well aware of its moisture resistant capacity, im more interested in its anti flexing properties, id just like to add, I've called hardie tech 3 times about this and been told 3 different stories so if they don't know what it does then i don't really expect anyone else too. Also, they do claim it stiffens up a timber floor!

 

[The D]

show me

 

[charlie1]

I quote the tech dept on phone today... "the boards will stop your tiles from cracking when layed on a wooden floor"

 

[The D]

I quote the tech dept on phone today... "the boards will stop your tiles from cracking when layed on a wooden floor"

Ok you are on the wind up I’m not even going to bother.

 

[DHTiling]

FIGHT!!!!!!....

 

[charlie1]

Ok you are on the wind up I’m not even going to bother.

eh, no im totaly serious, why the hell would i be winding you up man??

 

[charlie1]

show me

Deano, this is straight from their website (top of the page)...
"A 6 mm thick cement backer board for tile and stone, to be used as an alternative to plasterboard or plywood for tiling on floors, masonry walls and countertops"

Additionally, I called them (tech dept) to find out more about it and how it should be fitted and they told me that it was not suitable for floor boards, it had to be ply wood first.

I called them again and they said the opposite. (So now there are saying what it says on their web site)

I called them again yesterday to finally try to get to the bottom of what the hell this board can and can’t do, I asked "what is the benefits of fitting these boards to a timber floor", she replied, "it will stop your tiles cracking" ...that was it... very fluffy answer imo!

It was very clear to me on 2 of the 3 calls that the tech dept did not really know what the where talking about, there answers not only differed but there answers to specific questions where very fluffy / vague.

Look at their website, they are clearly claiming their boards have anti flexing properties on timber floor or you would need to plywood first then fit the hardier but they are clearly saying there boards are a replacement for plywood on a timber floor!!

I’m just trying to get to the bottom of this, do you need to plywood a timber floor first as per British standards or do these boards irradiate the need for plywood... that is the million dollar question that hardie cant even answer

 

[beanz]

Charlie, what they are saying is that it's a replacement as a tiling surface. Not a strengthening aid. Before, if you got a timber floor solid, but it was floorboards, you couldn't tile it without over boarding with ply.

 

[charlie1]

Charlie, what they are saying is that it's a replacement as a tiling surface. Not a strengthening aid. Before, if you got a timber floor solid, but it was floorboards, you couldn't tile it without over boarding with ply.

then as per British standards you would still require to overboard with ply to add strength, then fit hardie?

 

[The D]

then as per British standards you would still require to overboard with ply to add strength, then fit hardie?

yes what is your point ?????

 

[Dougs Third Go]

then as per British standards you would still require to overboard with ply to add strength, then fit hardie?

not if floorboards are deflection free, glue and screw hardie straight onto floorboards to give a good tiling surface.

 

[The D]

Ok I just popped in to CTD and picked up the Hardie bumff
Use minimum 15mm wbp plywood or minimum 18mm T&G flooring grade chipboard.
Ensure floor satisfies requirements of local building regulators and does not deflect more than L/360for ceramic tiles and L/720 for natural stone.
Excessive flex will cause the tiled floor to crack .
Joist spacing not to exceed 600mm centres

 

[The D]

So the way I use these Hardie boards is if I have a floor that is chipboard and it is free from deflection I will over board with 6mm Hardie backer board so that I have a sub-straight that is suitable to receive tiles.
If I have a chipboard floor that is not free from deflection then I remove the chipboard brace the joists and add noggins then replace the chipboard with 18mm ply then install the 6mm Hardie backer board so that I have a sub-straight that is suitable to receive tiles.

 

[charlie1]

So the way I use these Hardie boards is if I have a floor that is chipboard and it is free from deflection I will over board with 6mm Hardie backer board so that I have a sub-straight that is suitable to receive tiles.
If I have a chipboard floor that is not free from deflection then I remove the chipboard brace the joists and add noggins then replace the chipboard with 18mm ply then install the 6mm Hardie backer board so that I have a sub-straight that is suitable to receive tiles.

thanks deano, you have pretty much covered it all! You know, if you ever decide to pack in the tiling you will get a job in hardie tech support no problem as you have more info on there gear than all of them i called put together. Thanks again mate!

 

[beanz]

Deano, why not just put the chipboard back!?!

 

[The D]

Deano, why not just put the chipboard back!?!

There is nothing wrong with doing that if you want but if I have the chance to get rid of chipboard I do as it is pants