Underfloor heating and Tiling suspended timber floor advice

[Richb78uk]

I am renovating my kitchen myself and so I don't mind things that are difficult to change being over-engineered a little but there is so much conflicting advice out there I am hoping for some good advice from you guys!

The floor is suspended timber floor, joists seem to be about 450cm apart and seem stable and sound and I want to install ceramic or travertine tiles with electric underfloor heating.

The advice so far which I am happy with is:
1.Remove Pine t&g floor boards, and replace with 25mm WBP ply adding regular noggins below (ply screwed down at regular intervals)
2.stick down 10mm tile cement insulation panels with flexible adhesive
3.install electric underfloor heating cable
4.tile on top of that with flexible adhesive.

Could or should insulation be installed between joists (ie loft insulation) aswell as insulation board, or could this be used instead of insulation board which would reduce raising floor height by 10mm.

Thanks
Richard

 

[Richard C]

The advice so far which I am happy with is:
1.Remove Pine t&g floor boards, and replace with 25mm WBP ply adding regular noggins below (ply screwed down at regular intervals)
2.stick down 10mm tile cement insulation panels with flexible adhesive
3.install electric underfloor heating cable
4.tile on top of that with flexible adhesive.

I’d be happy with that; fix the ply into joists every 200mm. You should consider laying an SLC over the top of the heater mat, it protects the cable during tiling & if you bed it in tile adhesive you will never get it up if you even need to repair. Noggins are essential to support cut edges but adding them elsewhere will do relatively little to increase overall floor rigidity; what is size/pitch/span of your floor joists? Seal the back & edges of the ply with SBR primer before lying. Flexible powder cement adhesive only on floors not tub ready mix. Never use light coloured grout on floors, especially kitchens.

Personally I question the wisdom/need for electric UFH in a kitchen. They tend to be pretty warm places anyway & many kitchen installations prove to be overkill & spend most of the time switched off. Electric UFH can also be expensive to run.

Could or should insulation be installed between joists (ie loft insulation) aswell as insulation board, or could this be used instead of insulation board which would reduce raising floor height by 10mm.

Installing loft insulation below the floor will do little to improve insulation unless it’s in close contact with the floor; difficult to achieve. Celotex or similar would be better tightly fixed & supported between the joists. A tile insulator/backer board under the mat will improve warm up time & help with efficiency but read my comments above.

Use only quality trade tiling products not cheap DIY, it’s generally crap ; only prime if addy manufacture recommends it; not usual with powder addy; never use PVA.

Read tiling sticky & forum archive posts for more info & to avoid making potentially disastrous & expensive mistakes.