Help with a few tiling questions, Thanks

**refurbin** · 31-05-2011

Hello All, Any advice for a job that i'm undertaking will be gratefully received, thanks for your time in any replies. Ive got a kitchen floor to tile. half concrete and half floorboards. And looking to put in underfloor heating without putting too much height on the floor. Is it suitable to simply board out the whole area in 12mm plywood, attatch the mats directly then use a flexible adhesive and tile over the top? Ive got 600x600 porcelain tiles. It would kill me if the underfloor heating stopped working, is what i'm suggesting a suitable method? Is any flexible adhesive suitable? Is there an advantage with the 2-part(is that adhesive and primer?) or the mix-with-water stuff? (no experience with adhesives as you can tell) Is there any real difference? The fella in the shop was so heavily pushing some ready-mixed stuff at £35 for 4 square meters that I felt as though I needed some proper advice. Also, is the use use of insulation boards a nicety that would cut down on heat-up times/reduce the waste heating by a bit? I can do with slightly higher bills to save on the height and initial cost of insulation boards. Is what i'm thinking of doing ok, or is there a better way? It would be happy to keep the height down if it was just a bit more expensive to use. Thankyou for any replies to what must be a too-many-times asked question. Cheers!

**suave** · 31-05-2011

welcome to the forum m8

**whitebeam** · 31-05-2011

Hi and welcome..

In 4 metres square area how much screed is there compared to floorboards...

Powdered single part flex would be your best bet.

**chille** · 31-05-2011

Insulate mate or the bills will be a lot higher than the floor height, ply is garbage, as above 1 part flexi adhesive will do the job

**Colour Republic** · 31-05-2011

Originally Posted by whitebeam

Hi and welcome..

In 4 metres square area how much screed is there compared to floorboards...

Powdered single part flex would be your best bet.

The areas 20sqm mate

The store advised a ready mixed addy covering 4sqm per £35 tub

Has to be Topps me thinks

**refurbin** · 31-05-2011

Thanks for the quick replys. actually the kitchen floor is about 23m squared as i've knocked through to a reception room, thats why there is half concrete(actually 40%). Cheers for the advice, i'll use the 1 part flexi, does that stuff on top of the 12mm ply let me get away without the insul boards? Do you think its best to use 12mm ply for the strength? Would it be better to use thinner ply(6mm?) and use 6mm insulation board? to keep the height down? Or would this be less strong? Could do without cracked tiles. Looking for the best of both worlds i guess(keepin the height and cost down plus enough strength to stop the tiles cracking). Is it a masssive difference in heating costs? I will do the right thing if i'm being unrealistic, those insulation boards have a fruity price tag unfortunately. Looking to be in the place for at least 5 years, so realise that they are cost effective in the end but the wallet has an echo at the moment! Thanks again for spending the time for any replys, cheers all

**refurbin** · 01-06-2011

Actually wasn't Topps. Thought i was on friendly terms with a local little shop, realised i was getting the sales pitch and walked out. Would be great to know where to get decent grout and adhesive without getting skinned alive for not having a trade account. Really appreciate all advice and help, cheers

**Colour Republic** · 01-06-2011

Floor Tile Adhesive*-*Tile Adhesive, Tiletrim And Spacers*-*Tile HQ

By the way the 12mm ply isn't suitable. Do you have deflection in the timber floor?

**refurbin** · 01-06-2011

Cheers for the reply, A bit gutted that 12mil isn't thick enough. The builder was quite experienced so i took his advice. We found that there was some deflection, so nailed some 4x2 from the joists vertically to add strength to the joist(sorry for the numpty explanation, they are nailed 90 degrees to the joists nearest to the concrete floor and pointing down and firmly against the ground to add extra support to the last joist before the concrete in an attempt to stop any flex between the two different floor surfaces). Its gonna be my worst nightmare to ruin the underfloor heating or crack tiles. I'm not looking for a textbook install if you chaps with the experience can help me achieve underfloor heating without 18mm ply and 6+mm insulation. I'm happy to do this and avoid big problems in the future, just want to know if these are nice things to do, or if doing anything less is gonna wreck the elec heating or crack a tile. Every bit of advive is really appreciated. If I do have to get a thicker ply(is18mm required?) and go for the insulation board(would 6mm fibre board be sufficient?), then to add the 9mm tiles plus adhesive I guess i'm looking at a big jump between the hallway and the kitchen which i will have to live with(or get a step ladder), are there any suggestions in how to deal with this massive jump in floor height? As always i'm looking for the experienced hand's method finding the best solution, but accept that i may be asking too much, thanks for any replys...

**chille** · 02-06-2011

Could use 6mm No More Ply then the insulation boards or take floor boards up and board the joists directly with wbp ply level with the concrete floor and insulate over the lot