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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Painting, Decorating & Tiling Questions >> Underfloor electric heating and adhesive amount https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1223482861 Message started by londonman on Oct 8^th, 2008, 5:21pm

Title: Underfloor electric heating and adhesive amount
Post by londonman on Oct 8^th, 2008, 5:21pm

2.5 sq m of mat and I reckon about 8-10kg of BAL Rapidset adhesive. Jeez...by the time I've finished the adhesive is going to cost more than the rest put together! Is this sort of amount of adhesive normal?

Title: Re: Underfloor electric heating and adhesive amoun
Post by jasonB on Oct 8^th, 2008, 6:02pm

For that sort of area which is about average I'd recon on using a bag (25kg) and throwing any thats left. BALs figures are a bit optomistic and the mat will need more than if you were just laying tile with a thick bed/solid bed trowel.

The main thing is you should not be using Rapadset, you need Rapidset FLEXIBLE and a flexible grout as well to allow for expansion & contraction as teh tile/adhesive bed warms & cools. Single part flexi would also be OK unless you need to walk on the floor in a few hours. Also don't turn on the UFH for 28days to allow a full cure of teh adhesive.

What mat are you using, I like the Devi ones as the whole backing is adhesive so it stick well to the primed surface.

Jason

Title: Re: Underfloor electric heating and adhesive amoun
Post by londonman on Oct 9^th, 2008, 10:52am

Thanks Jason - that's reassuring to know. Hoped you might pop by. It is Rapidset Flexible - careless typing.

The mat is by Elektra warmfloor. Only another two to go down elsewhere :-/

Title: Re: Underfloor electric heating and adhesive amoun
Post by jasonB on Oct 9^th, 2008, 5:04pm

Just ripped up 20m2 of slate with Electric UFH, what a pain, you have to keep cutting the wires away and I snapped my Armeg tile removal chisel after the first three tiles :(

Jason

Title: Re: Underfloor electric heating and adhesive amoun
Post by londonman on Oct 14^th, 2008, 9:08pm

wrote on Oct 9^th, 2008, 5:04pm:

Just ripped up 20m2 of slate with Electric UFH, what a pain, you have to keep cutting the wires away and I snapped my Armeg tile removal chisel after the first three tiles :(

Jason

I don't envy you.

I'm now getting to be a bit of an expert! Found the best way is to ignore their suggestion of a standard notched trowel and use a normal float instead. Float a skim coat on the floor, lay the mat on top, apply skim all over the top pressing down hard. if it's on a wooden base then rout or chisel out a small recess for the end termination and also the cold junction or whatever its' called otherwise they stick up like the proverbial and you end up using much more adhesive when you come to do the tiles.

Title: Re: Underfloor electric heating and adhesive amoun
Post by Twobarrows on Oct 16^th, 2008, 12:56pm

londonman wrote on Oct 8^th, 2008, 5:21pm:

I've got 4 x 7.5kg bags of BAL Rapid with Flex addative going cheap if you are interested, collect only, FLEET, near Farnborough.

Title: Re: Underfloor electric heating and adhesive amoun
Post by londonman on Oct 16^th, 2008, 5:29pm

Thanks for the offer, TB, but you're a bit far away.

Title: Re: Underfloor electric heating and adhesive amoun
Post by londonman on Oct 18^th, 2008, 11:08am

God....I'd forgotten just how much I HATE tiling! In retrospecrt might have been better to get a pro in but I could see problems with logistics. For example, l;aying down the UFH mat first in the cement then having to come back the next day to maybe lay the whole tiles. Then another day to lay the cut tiles. What does the panel think? How practical for a pro?

Three rooms to do. All with underfloor heating ranging from 3sqm to 1sqm.

Room 1 - roughly 3 sqm floor tiles. Shower enclosure 1200x800 tiles to ceiling on two sides

Room 2 - roughly 3sqm floor tiles only

Room 3 - ahower cubicle - three sides 800mm - floor 1 sq m

Title: Re: Underfloor electric heating and adhesive amoun
Post by jasonB on Oct 23^rd, 2008, 6:41pm

Roger I tend to lay the mat and then tile straight onto that all in one go. Also on such small areas its easy to do the cuts as you go.

Just bought 50No 600x900 black linestone tiles for this kitchen, not much change out of £1000 at trade, and the boards for the carcases came to £2300 ::)

Jason

Title: Re: Underfloor electric heating and adhesive amoun
Post by londonman on Oct 24^th, 2008, 7:44am

I can see the benefit. The only problem I see...but I'm sure you've a solution!...is that the mats have a couple of connections that are quite proud and so need the adhesive being built up to accomodate. Too thick a layer of adhesive and the weight of the tiles will squidge it out resulting in the tiles being out of level?

Title: Re: Underfloor electric heating and adhesive amoun
Post by jasonB on Oct 24^th, 2008, 4:41pm

I chase the leads, connections and thermostat tube into the floor be it wood or screed.

It takes a while o be able to judge the consistancy of the adhesive, too dry and you dn't get such a good bond, too wet and the tiles will just flaten the ridges.

Jason