Hardie Backerboard

[Taz8130]

Just been on backerboard website and am a bit confused.

Can anyone confirm whether, when using backerboard in a shower area, you have to install a membrane prior to fixing the board to the wall.

It seems to indicate this on the website, but I was under the impression that due to the nature of the backerboard, you would'nt need one.

[cornish_crofter]

I've used both this product and aquapanel in shower areas.

I've always believed that these products replace the membrane if applied correctly.

[grumpygrouter]

The Hardie (and aquapanel) is impervious to water, i.e. it does not breakdown when in contact with it. As such, your tiles should stay in place even with considerable water penetration. If however, you have water getting through in such quantities and it never dries out, the water will eventually make it's way through the board to the substrate. Tiles will still stay in place though. What you might get is leakage through to other areas in this case. But it would be taking a huge amount of water in the first place to do so.

You should always seal the joints in the board anyway but if you really, really want to keep any water in the area then tanking is the best bet.

For normal family day to day use though, it should be fine just to seal the joints to provide a "waterproof" environment.

[Taz8130]

Thanks for the advice. The confusion has come about due to the statement that I read on the backerboard website (help & support section)

It states:

Areas exposed to water
When Hardiebacker™ backerboard
is installed behind showers you need
to install a PVC membrane sheet
to assist in the prevention of water
ingress. Corners of walls should also
be flashed with a pvc flashing or
similar.

http://www.jameshardie.co.uk/pdf/ins...eBacker500.pdf

[Dave]

That is vapour membrane behind the hardi backer......personally i prefer just to use a membrane on the walls to start with.. then it is fully water tight from the beginning..

But backerboards do have there place....then take more weight per sq mtr than standard plasterboard etc......so ideal for stone and large tile installations and tanking membranes can be applied to them to make them fully water tight and still carry the weight...

[cornish_crofter]

Hmm, stand corrected then.

Hardibacker has always been sold to me as being completely impervious to water.

Maybe I'll stick with Aquapanel in future, or even aqua board. I'm using aquapanel at the moment.

[grumpygrouter]

Aqua panel has similar properties to Hardie backer, water will permeate through it though it will not breakdown, the same as Hardiebacker.

Only true way to stop penetration is to have a waterproof layer! As in the dictionary definition of waterproof.

[LOFTHOUSE]

Yep, that liner they speak of is for the pan, and it goes on before you apply the hardi to the studs. Follow? See, the pan PVC/Chloroyl Liner runs up the wall 12 inches with a nail/staple at the top. Then, your hardi will hold the liner in place, be sure to do a neat job fitting the corners between studs, and countersink all nails, sand timbers/splinters.

I use Hardi a lot, can't stand the dust it generates. Do you all have Custom Building Products over there in the UK? They make a foam "EZ Board" sandwiched between two sides of fiberglass/masonry, that cut's with a utility knife. Splendid, but it does have it's weaknesses, it tends to be concave or convex depending on the framing. Give it a shot sometime.

Oh, and all of these boards accept water, however they should have anti-mold properties. When you roll on a paintable membrane like Mapeilastic/Laticrete, most manufacturers recommend setting tiles with mortar only. I like to use Type 1 Mastics personally.

[wolfe tile]

Don't ever use Hardi-backer its cheap, and in cold climates it can be defective. I worked for someone who used it and it caused nothing but problems. I would consider using Perma-Base or something that is mildew, water, and fire resistant. Its may be too late now but in any shower with steam units I cover all underlayment inside shower with Pro red, or Aqua seal a waterproofing membrane My shower pans require pemits so I Know exactly what needs to be done in order to pass inspection. Plus I have seen plenty of shoty work and fixed it.

[John F]

I too was confused by the UK Hardiebacker installation instructions so I contacted the company for clarification. This is a summary of the helpful response I received:

• HardieBacker is water resistant but not waterproof. That is to say it is not harmed or adversely affected by water. It will absorb any water that gets through the tile and adhesive layers, releasing it back into the atmosphere of the room when the conditions change.
• An impervious plastic barrier sheet is required as a last line of defence to protect the sub-frame behind the board in areas that are to be continually wet for extended periods i.e. around a shower or in a wet room. Polythene sheet is just as suitable as the PVC sheet over-proscriptively specified in the UK instructions.
• Don't get hung up on the recommendation in the UK instructions that studs should be out of alignment by no more than 3mm in 4m (precision carpentry?). Studs should just be straight and properly aligned (which is all the US instructions require anyway) so there is no chance of a tile rocking on a joint between boards.
• Alkaline resistant jointing tape bedded in tile adhesive is required to strengthen the joints and homogenise the boards into one monolithic unit. Its presence forms part of the warranty. It assists in preventing the grout lines from cracking as the boarded wall will move as one rather than a series of individual pieces.

I would personally apply the jointing tape at the same time as the tiles and avoid joints between tiles coinciding with joints between the boards.

John F

[whitebeam]

Plasterboard and then tanking seems a more secure way, removes any if's or butt's

[obobsmith]

Plasterboard and then tanking seems a more secure way, removes any if's or butt's

Tend to agree here, have had a couple of jobs over past couple of months where regardless of plasterboard or hardibacker being the surface, the water ingress had rotted a) the studs in the wall and b) a supporting floor beam, nasty. So perhaps tanking wet areas regardless of the substrate is best practice.

[Gazebo]

Tanking with a membrane or marmox is waterproof as is wedi board, aslong as you finish any joints correctly.

They are also lighter than haribacker/aquapanel, easier to cut, have some thermal and acoustic properties come in a variety of sizes and I love em.

[John F]

Tend to agree here, have had a couple of jobs over past couple of months where regardless of plasterboard or hardibacker being the surface, the water ingress had rotted a) the studs in the wall and b) a supporting floor beam, nasty. So perhaps tanking wet areas regardless of the substrate is best practice.

Obobsmith, looking back through this thread there are a couple of posters who thought that Hardiebacker is impervious to water and doesn't require a membrane. I'm not surprised you have encountered rotten studs behind Hardiebacker if people have been installing the boards without a membrane because they have relied on the advice of their builders merchant rather than reading the instructions. The instructions don't require tanking to be applied, so why go to the trouble and expense? I don't like the idea of using plasterboard in wet areas, but I suppose it would be OK with tanking. Too many people seem to think that water resistant plasterboard is waterproof and use it without any further protection against water damage to the board and the studs behind.