what type of backing board is best

[paul westcott]

Hi..looking for some advice from the professionals please. Not sure if i'm posting in the right place.
I have been recently doing my bathroom and was about ready to start tiling when i came across this forum. After removing the old tiles most of the plaster skim came off, so to make the walls more level i took the rest of it off leaving just the browning plaster coat (browning probably has been up since the property was built i the early 80s), I naively thought that i could seal the browning as it was in great condition and begin tiling on top off the browning but after coming across this forum the other night i've luckily learnt that this is not good practise and shouldn't be done (although some have said it should be ok, i dont want to take chances).
As i want to use 600 x 300 ceramic tiles and after reading many posts it seems i would also probably be a bit overweight if i was to just get the walls skimmed again( i reckon about 23-24kg per square mt) so probably not the best thing to do as i want peace of mind with the finished job.
So ive decided its probably best to remove all the browning (about 8-11mm thick) and use a 6mm tile backing board this would also help so the tiles will not be nearly level with the door architrave once there put up and have better water resistant properties.
Their seems to be many different types available so just wondered which one would be good to use, all the walls in the bathroom are solid block behind the browning and my thoughts are the browning may have helped as insulation too so something that also had insulation properties although it will be small it can will only help.
Any advice would be greatly received.
Thanks, Paul

 

[paul westcott]

Also happy to post pics and work in progress as its the diy side of the forum if anyone is interested.

 

[Bond]

Hi, 6mm insulating tile backerboard is available, personally l have only used it in a flooring situation.
Presumably it’s for boarding an outside wall.

Hang fire, no doubt others will be along in due course, and confirm whether it’s suitable for walls or not.

 

[Flintstone]

6mm insulation is suitable for bathroom walls, solid bed of tile adhesive behind it and fix it to the wall with screws and plugs with washers

 

[Waluigi]

Personally I’d prefer to up the size of the board and dot and dab with tile adhesive.

The boards are more rigid and it’s easier to get flat and Plumb.

I’d consider plasterboard too. 12.5mm

Door lining wise- I’d tack on a slightly larger door liner. By the time it’s filled and sanded you’d not notice. In the grand scheme of a full refit, it’s only a small part. Getting the walls flat and Plumb is the single most important thing of any job in my experience.

 

[paul westcott]

Thanks for the replies. I'm going to see what thickness i have after removing the browning which i'm currently doing, the bathroom is not big but ideally i want to put the backer board around the bath area as i understand it has better moisture repellent then plasterboard and then see if i can use plasterboard for everywhere else, the walls should be preety level as the browning is attached to blockwork or similar.
thanks again for your help

 

[GoneGuy]

Whichever brand you use, make sure you tank the wet areas.

 

[paul westcott]

Hi Adey
Is it really necessary to tank the wet area if i'm using hardibacker board or similar? will have a bath with electric shower. If so do i just tank the wall the bath runs across and the back section where the shower is fixed too.
thanks

 

[Waluigi]

In reality it’s highly unlikely to ever cause issues as an electric shower can’t really be considered as a power shower.

On paper it should always be tanked as it’s not considered waterproof by any means despite some of the Hardiebacker Reps suggesting that moisture won’t pass through it.

 

[Tile Shop]

Hardie will take in moisture if not tanked. But unlike other porous substrates it will hold the moisture without going mushy or expanding, and water will later evaporate when the shower is not in use through either the grout joints or into the cavity behind (depending on how its fitted)........ and even into the wooden studs holding it up. So the reps stand by "it doesn't need tanking".

But look at it this way, you have a leak between the tiles, or you have certain areas in your shower subject to excessive moisture, from through the grout or a failed area of Silicon. The Hardie soaks up the water...... but how much water will it soak up? what happens when it can't take any more on? What if there is nowhere for the held water to evaporate to? it will fill up till it pis......tachios out.

Hardie is water resistant, not waterproof which is what is required by the new British Standards. Yes it has to be a really substantial amount of water to cause a problem with Hardie, but for the sake of a 40-50 quid tanking kit compared to the amount this project is costing you already, and how much it could cost to fix a failure, is it really worth the risk of cutting corners?

 

[paul westcott]

ok ill tank around the shower and bath part for extra protection. Looks like i'll be going with 12.5mm wall boards but as some of the walls are not 100% i will probably have to dab n dot to get a good level and then mechanical fix. So ive been leaning towards the Marmox boards as they seem lighter the the hardibacker or aquaboard and it says you can dab and dot with the Marmox board but not with the others and then fix using their dowel pins where i have but the dabs.
Does this seem the right way to go ? also do i need to seal the block i will be fixing boards to and do i just use tiling adhesive for the d/d.
Appreciate all your advice,thanks again

 

[Time's Ran Out]

Just use Wedi/Jackoboard and save on the tanking, just the joins and corners.
Take more surface weight then any of the paint on products.

 

[paul westcott]

If i use plasterboard on a couple of the walls not in the wet area will dab and dot be strong enough to hold all tiles or would it also need fixing to the wall with some sort of fixing for extra strength, I will be using 600 x 300 tiles 10mm thick (worked it out to roughly 23-24 kg per sq mt and do i need to prime the blocks first? Ive decided on the Marmox boards for everywhere else as they can be dab n dot to help level the wall a bit and fixed with the dowels afterword but would save a bit of money if i plasterboard the other areas.
Thanks

 

[Waluigi]

The only time you need to mechanically fix plasterboard to a block/brick wall is if it’s the insulated board which require just two fixings to comply with the fire regs

That said, it won’t do any harm.

 

[Waluigi]

No need to prime the blocks unless they are very dusty. Which then might need a watered down PVA.

Remember- you don’t use tile adhesive for the plasterboard, you use Dri-wall Adhesive.

 

[paul westcott]

Thanks for the quick reply Waluigi is there any specific fitting to use?
edit posted before your last reply, yes will use dry wall adhesive thanks for the heads up ..what about taping the joints would i do it the same way as the backer boards?

 

[Waluigi]

Orbry 50 Stainless Steel Tile Backer Board Washers - https://www.tilefixdirect.com/product/ALSBW50?gclid=CjwKCAjwmdDeBRA8EiwAXlarFhcWMr2rvwoAc9KouIlPAlibzXx3XGxuVd7B-MyggNrXz9RAGZxa1BoCZXMQAvD_BwE

 

[paul westcott]

Thanks again...out of interest i'm using the spankers to fix for the Marmox board could i use them on the plaster board as well done the same way

 

[Waluigi]

In my experience, I just use a large flat wood bit and use them on the plasterboard just to take the paper face off and a millimetre or two off the board so that the washer sits flush/recessed.

They don’t bite in on plasterboard like they do on the foam board.

 

[paul westcott]

I'm probably being really thick here, but if i use the washers in the link how do i get the wall plug into the wall after the wall adhesive has dried. Do you just drill the hole big enough for it to go through the board say 10mm hole and the washer holds the board in place..sorry if it sounds like a stupid question..

 

[Waluigi]

Drill the hole, push the plug in, knock the plug home with a screw, then screw the screw in.

 

[Waluigi]

This was done on a skimmed wall. Quite a few fixings.

The washers were recessed, filled with adhesive and the wall was then tanked.

 

[paul westcott]

Brilliant..thanks for your time

 

[paul westcott]

just a few more questions..when tanking it would you put the mesh tape over the fixings and brush the waterproofing coating on them? also what tanking product would you recommend i was leaning towards the Ardex wpc.
When tiling over plasterboard which is not tanked what would you use for the joints, similar to the backerboard tape the joint and feather over with tile adhesive
Many thanks