Tiling extension. Suspended timber floor. Use 22mm chipboard?

[Jason Smith]

I have a extension that is approx 20m2. The floor will be suspended timber, with wet UFH fitted below. Joists are at 400mm centres, and span about 2.6m

I was going to fit 18/22mm chipboard over. I am reluctant to over ply, as it will reduce heat transmission from the boards, and I have very limited height avaliable. Can I tile directly onto 22mm chipboard?, do I need to use a decoupling mat? Boarding with ply directly would mean that it is not T&G, What is the best solution/

 

[Chalker]

Best to use is 22mm fermacell flooring, straight onto the joists. You can tile straight onto it too, as its gypsum based.

 

[matthew_uk_666]

I'm certainly not a professional, but I've had to do similar while renovating my house...

I used 22mm t&g chipboard glued on all edges and screwed down to the joists and additional noggins on all sides, I then over-boarded with 12mm plywood screwed every 150mm with 30mm screws. Agreed this is not to British standards (I.e. 15mm ply) however it makes for a very sturdy floor with virtually no deflection.

It's tanked with tilesafe and the tiles stuck down with keraquick and latex plus...

I solved the problem of the door opening with a saw...:regular_smile::regular_smile:

 

[Ajax123]

Screed it??

 

[Chalker]

I'm certainly not a professional, but I've had to do similar while renovating my house...

I used 22mm t&g chipboard glued on all edges and screwed down to the joists and additional noggins on all sides, I then over-boarded with 12mm plywood screwed every 150mm with 30mm screws. Agreed this is not to British standards (I.e. 15mm ply) however it makes for a very sturdy floor with virtually no deflection.

It's tanked with tilesafe and the tiles stuck down with keraquick and latex plus...

I solved the problem of the door opening with a saw...:regular_smile::regular_smile:

the trouble with all that is it will insulate too much. Defeating the object of underfloor heating.

 

[Ajax123]

the trouble with all that is it will insulate too much. Defeating the object of underfloor heating.

Not if you get rid of the sheet timber over lay and use a screed instead....

 

[matthew_uk_666]

the trouble with all that is it will insulate too much. Defeating the object of underfloor heating.

I have wet underfloor heating too... it takes longer to warm up than other rooms but still happily gets to temperature.

 

[Ajax123]

I have wet underfloor heating in my lounge, kitchen and bathroom in anhydrite (Gypsol) screed. It warms up really quickly compared to the rooms that still have rads.

If I could work out how to upload pics I could show you how I did it....

 

[Ajax123]

 

[Chalker]

How thick is the screed?

Nice way of doing it over timber floor.

how do you work out the weight?