Installing Underfloor Heating & Tiles on Wooden Floor

[tryinghisbest]

Hi All,

I'm looking to tile my bathroom floor but put an electric heating mat under it. I've seen the one at B&Q called heatwave. The subfloor is wooden floorboards and heatwave suggest doing it in the following order (bottom up):

Tiling (Finished Floor)
Adhesive
Heating Mat
Insulation Board
Adhesive
Wooden Floor (Sub Floor)

Looking around online some people suggest using self levelling compound on top of the heating mat first before adhesive, is this necessary? Also with the wooden floorboards do you think I'll have issues with a tiled floor. I'm guessing it should be ok if the floorboards are pretty level?!?

Has anyone had experience fitting these and got any tips - avoiding common mistakes etc?!

Would appreciate your comments, looking to improve my DIY skills so any advice welcome

Cheers

T

 

[mointainwalker]

//www.diynot.com/forums/viewtopic.php?t=277414

Have a look at the comments from ericmark and Detlef Schmitz and then perhaps do a search on the topic in both Building and Electrics.

I don't have any experience myself except to say that if you go ahead you should consider the cost/necessity of the insulation board.

What is normally proposed is ludicrously expensive for a pathetic 5 mm/7 mm of insulation and since the heat is staying within the habitable space anyway, I really question if it is needed.

 

[tryinghisbest]

A lot of people seem to recommend insulation board to cut down on electricity bills. Thanks for the tips and the info

I suppose the extra question I have is, I want to tile under the toilet ( I know I can't put UFH under that and wouldnt want too!) - if you can't use the insulation board under fixed fittings (which seems to be a no no), do I just substitute the insulation board with plywood of the same thickness so floor continues to be same level?

Thanks

T

 

[mointainwalker]

...do I just substitute the insulation board with plywood of the same thickness so floor continues to be same level?

Yes.

 

[Richard C]

UFH often sounds perfect but I question the wisdom of installing it as a secondary heating system. They can be expensive to run & disappointing in use unless you use the room the same times every day & run it on the timer; otherwise you will have to turn it on 30 - 45 minutes before using the bathroom which can be impracticable. Assuming your bathroom is on the second floor, you will get heat permeation from downstairs which will take the chill off the tiles; personally, I’d install an oversized towel rail or stick with a conventional radiator.

Using SLC over the mat gives a flat tile base, very important if using large format tiles. It also helps prevent accidental damage to the heater mat when tiling & will give you an outside chance of being able to repair it if it packs up; if you bed the mat in cement tile adhesive, you will stand absolutely no chance of ever repairing it. Floorboards can be over boarded but it depends how rigid the floor is, I prefer to replace with WBP ply which considerably reduces risk of tile failure; the thickness of ply you need will depend on the floor joist size/pitch/span.

I also advise you read the Tiling Forum (where you would have been better to post this) the sticky & archive posts before you commit yourself. There are many threads on UFH & a lot more info & advice on tiling which may prevent you making disastrous & potentially expensive mistakes.