Electric UFH Self level or not? - Tile Advice

[Regis Quality Tiling]

Hi everyone. I'm doing a bathroom floor over existing floorboards. I'm also adding a 1.5 sq m electric heating mat before tiling with 30 x 30 granite tiles. I'm applying thermal board which I'm sticking with adhesive. Been told don't need screws or tape as adhesive will do. My dilemma is whether I then self level or just tile directly onto the matting? If I don't level think I will struggle with my levels across the floor. If I do use self leveller first, how do I make sure it doesn't flow through the holes left accessible for pipework coming out of the floor? Should I batten small areas around ? I've used self leveller before but only on ground floor solid floors
Any advice thoroughly welcome. Thanks,
Nick

 

[Dave]

The boards need fixings as well on a timber floor. Screws and washers. 👍 and i always slc over ufh.

 

[Regis Quality Tiling]

The boards need fixings as well on a timber floor. Screws and washers. 👍 and i always slc over ufh.

Thanks. Instructions from Deltaboard and shop (Tileflair) both say adhesive sufficient but think will take your advice.

 

[Dave]

Thanks. Instructions from Deltaboard and shop (Tileflair) both say adhesive sufficient but think will take your advice.

The slc encapsulates it much better.

 

[Regis Quality Tiling]

The slc encapsulates it much better.

No sorry - meant applying the thermal board onto the floorboards.
I def will be applying an slc. Thanks.

 

[Dave]

Thanks. Instructions from Deltaboard and shop (Tileflair) both say adhesive sufficient but think will take your advice.

Ah ok. I personally wouldn’t without fixings.

 

[Regis Quality Tiling]

Ah ok. I personally wouldn’t without fixings.

Thanks. I've bought some so will use them as a belt and braces solution. Thanks for the help.

 

[Regis Quality Tiling]

Hi Dave, if you're there??!!!
Ready to apply self leveller onto thermal insulation board. Heated mat in place. Should I prime the thermal board first or just apply the slc straight?
Thanks

 

[Dave]

Hi Dave, if you're there??!!!
Ready to apply self leveller onto thermal insulation board. Heated mat in place. Should I prime the thermal board first or just apply the slc straight?
Thanks

It won’t hurt no , especially if the boards are dusty and the ufh mat isn’t particularly sticky.

 

[Regis Quality Tiling]

Final question - hopefully! 30cm square polished granite tiles. Going on top of slc and heated floor. What size notch trowel for this. Would normally go with 12mm aware notch. Too much??