Underfloor heating on chipboards

[Rich]

No it is not essential, some people dont SLC and tile directly over the wires to save time but in my opinion it is much better to SLC as it protects the wires while you are working, it helps to spread the heat over the floor and most importantly it is far easier to get 100% coverage of adhesive under the tiles.

If you choose to tile straight over the wires make sure that the adhesive you are going to use is suitable. Building up over the wires and then tiling might well be over the max depth of the adhesive.

 

[grumpygrouter]

Could you avoid slc by buttering the tiles or is this essential

It is much slower/harder to do it this way. Even if you trowel the floor with the bare wires it takes you much longer because of the care you need to take to not damage the cables. SLC makes it a much more pleasant tiling experience with UFH, over and above the other benefits already mentioned. It would probably work out cheaper too as you will use much more adhesive to fill up the void between the cables and adhesive is generally more expensive than SLC.

 

[shogun rua]

Hi Again,

Im going to lay installation boards i was told today to put down with addy then screw down but to use washers is this what you would do?

Cheers

Paul

 

[grumpygrouter]

Yep, that's fine.

 

[shogun rua]

Hi,

Heres my plan lol

1. check the chipboard for deflection fix if needed.
2. lay insulation boards with rapid set and screw down with 25mm screws with washers( do i dot and dab or back butter?)
4. prime with the expensive primer.
4. lay electric mat to the installation instructions to the word.
4. lay slc (fibre based)
5. tile (do i need to use a plastic trowel?)

what do you guy think?

 

[Andy Allen]

have you checked to make sure its not a floating floor?

 

[shogun rua]

Hi Andy,

How do i check that mate?

Cheers

Paul

 

[Andy Allen]

a floating floor is just chip board over insulation with no fixings, try lifting some of the flooring and look for fixings where its screwed to joists, if there are none then theres a good chance its a floater in which case i wouldn't touch it with a barge pole.

 

[shogun rua]

great tip Andy cheers, so dont tile on floating floors then to move movement

 

[Andy Allen]

imo there to unstable, with to much deflection.

 

[shogun rua]

what do you think of the list did i miss anything?

 

[Rich]

Your list seems good as long as you follow each stage to the installation instructions all the way through the project. It is vital to get a solid bed of adhesive under the cement boards and the tiles, you shouldnt ever "dot and dab" anything apart from plasterboard on walls (that I can think of). This shouldnt be hard with your floor, trowel the adhesive on the floor and press the boards down into it firmly and give them a bit of a twist making sure that the corners and edges are well and truly bedded down into the adhesive, then the screws do a good job of pulling the boards down into the adhesive bed.

 

[shogun rua]

thanks 12mm trowel

 

[Rich]

Not for the cement boards, I use a 6mm on most floors. Only use a bigger trowel if I dont get a good coverage with that. A half moon trowel for laying the tiles and you will want to back butter the back of the tiles with the flat edge of the trowel before laying them into the adhesive bed as well, this should give you a better chance of getting 100% coverage

 

[shogun rua]

do you always back butter your floor tiles aswell as lying addy on the floor?