Advice on tanking and backing boards - TilersForums.com

[markfire]

I am about to embark on refitting my existing bathroom (1st floor) and would welcome some advice ref: wall and floor backing boards and tanking.

I am fitting a quad shower with one wall block and plastered and the other stud with a backing board, and then both walls tanked. What backing board do you recommend (aqua panel etc) and can I tank directly over the backing board, or do I need to seal it with something first?

Secondly, I am tiling the floor and fitting single wire underfloor heating (as a tile warmer). My existing floor is 22m T&G and i want to keep the increase in height to a minimum, do you recommend overboarding with 12mm WBP or a 6mm thermal backing board? The room is only about 6m2 (exc bath etc) and I would like to keep the height increase to a max of about 3/4inch (same height as the threshold) inc tiles if possible, any suggestions?

Many thanks....Mark

 

[GatesheadCol]

Hi Mark and welcome to the forum.

I recently did a bathroom floor with UFH over t+g

I used 6mm warm up insulation boards over the flooring.

Prime the floor, trowel your adhesive Flexi rapid set was what I used, then lay the boards screwing down at 300mm centres. Stagger the joints though, you should have no more than 3 boards meeting at a join rather than 4, sort of brick bond laying

Lay the UFH on this and then you have 2 choices.

You can either put SLC over the UFH or trowel directly onto it. Being very careful not to damage the wires if your doing this.

I laid straight onto the wires but after doing so I wish I had put SLC the floor as the second option takes longer cos you have to be so careful. The backer boards do not need to be primed.

Of course another thing to consider with the UFH is if there are gas pipes under your wood floor in the bathroom, there are differing opinions on whether or not you can lay UFH over them so check this out first. I was told by a Corgi guy that it shouldnt be done. (mine didnt have it luckily) but some say it can be dopne. Check with either Corgi or warm up.

 

[grumpygrouter]

Hi mark welcome to the forums. Would you be good enough to introduce yourself in the New Members forum and tell us a bit about your self. Thanks.

To your question. Firstly it is essential that your floor is solid! Thermal insulation board does not add strength ot the floor. You mak want to consider 6mm Hardie backer as na initial strengtheneing layer befor your insulation board.

As GatesheadCol says, it is much easier to tile onto a nice flat SLC layer than catching your trowel on the heating wires and possibly damaging them.

If you are putting something like Aquapanel into your shower area you will not need to tank that area. You may want ot consider dot'n'dabbing it onto the block wall. You will only need to seal the joints then as aquapanel is impervious to water. I would advice a cement based adhesive and if you use this you will need to prime the walls with acrylic primer prior to tiling. You didn't say what type/size tiles you were fitting, this would anable us to give more detailed advice.

Best of luck.

Grumpy

 

[Turkish]

That`s interesting Grumps, do you really not have to tank the aquapanel? What do you use to seal the joints? Do you use normal dry wall adhesive to dot and dab this to the wall?

Turkish:huh2:

 

[grumpygrouter]

Hi turkish, the reason you tank is to stop water penetration through to the substrate and also to keep the water into the area it should be. As backerboards like aquapanel are cement based and not gypsum like plaster, they don't break down when they come into contact with water and therfore the tiles stay where they are. You obviously need to seal the joints to stop the water getting passed those areas and if I recall aqaupanel, for instance, recommend flexy tile adhesive with their own jointing tape. I am sure James Hardie will have something similar as well.

Not sure about the dry wall addy but I believe you can dot n dab with rapid set adhesive to acheive the same thing.

Grumpy

 

[Turkish]

Thanks for that Grumps, another gem of knowledge to add to the small but growing collection!

Turkish

 

[wetdec]

Hi Mark,

If you are going to tank the walls then I would recommend you use one system for all rather than fiddling with tile backer and then a skimmed wall.

Personally I would recommend you plaster board your stud work as you are not gaining an advantage by using tile backer. When plaster boarded I would tank the shower area walls with Durabase wp tanking membrane and take it under your shower base to make the job right.

The Durabase wp tanking membrane is fixed like wall paper using tile adhesive and the your joints are strengthened ( corner angles) with a reinforced tape. We can make you a tanking kit up for you according to what you require. Take a look at the link below.


Your floor area as its 22mm I would overboard with a 6mm ply so crossing your existing joints, run some Unibond under the ply and nail every 150mm. When fixed run your cable out and run a leveler over the top finishing it to the top of your wire. (this is to give you a nice base to work off) The floor can then be tiled when dry with a flexible adhesive.




Wet room tanking systems here





tiler

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[markfire]

Thanks everybody for taking the time to give me such sound advice. I'm a bit paranoid about getting a leak in the tanking, for the extra few pounds is it not worth fitting a water resistant backer board (just in case!!)

 

[wetdec]

Simple answer is no, in this casew it would be a waste of money. A tanking membrane is designed to do what you want and membranes of this kind are in our opinion the best solution to tanking in these circumstances.

How to tanking with Durabase wp


If you have any worries or questions please dont hesitate to contact me via here or the site.

tiler

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[markfire]

Thanks 'tiler,' I have sent you a note via your link.

Grumpy, where is the new members forum? I can't see for looking...