Wet UFH on Block & Beam and Joists...

[curtly]

Hi everyone,
We've an existing kitchen floor on Block & Beam + starting an adjoining extension with wooden joists. (has to be due to slope)

We are wanting 'Wet UFH' across both surfaces finished off with tiles but only have a maximum height on top of block & beam of 80mm (including tiles), is this realistically do-able ?? I appreciate that screed is probably out of the question due to the lack of height :-(
The new wooden Joisted extension can be any height but obviously matching/overlapping the existing kitchen.

Any help or advice would be really appreciated

Thanks in advance

Chris

 

[One Day]

Hi, your absolutely best option is bekotec-therm from Schluter. It uses a very thin screed and is perfectly designed for tiles.
Other low profile ufh systems are out there but where you save on the system, you'll need to spend more on prep for tiling.
I've recently used nu-heat lo pro and to be fair, it's ok. Total build up height is about 22mm before uncoupling membrane and tiles.

 

[White Room]

Another one Vario PRO Underfloor Heating & Uncoupling - http://www.tiletown.co.uk/en/vario-pro-ufh

 

[Dumbo]

Should there not be a recommended thickness of celotex on top of block and beam floor . If I remember rightly we had to have a minimum of 80 mm to comply with building regulations

 

[curtly]

Hi, your absolutely best option is bekotec-therm from Schluter. It uses a very thin screed and is perfectly designed for tiles.
Other low profile ufh systems are out there but where you save on the system, you'll need to spend more on prep for tiling.
I've recently used nu-heat lo pro and to be fair, it's ok. Total build up height is about 22mm before uncoupling membrane and tiles.

Would the Nuheat LoPro Max require an insulation layer then chipboard underneath it first ?

 

[curtly]

Should there not be a recommended thickness of celotex on top of block and beam floor . If I remember rightly we had to have a minimum of 80 mm to comply with building regulations

For the extension area this should be do-able as its joists, the existing block & beam currently has 30mm foam + 25mm chipboard on top

 

[One Day]

Hmm, unsure. You'll need insulation. How much and how thick i can't say. Mine was into existing uninsulated concrete.
Nu-heat are clued up, might be worth a call.
There's got to be thinner alternatives in 2017?!

 

[Dumbo]

Take out chipboard . Put in 125 guage slip coat (I think that's the thickness) fix ufh to insulation then pump screed on top

 

[Dumbo]

If you can fit in wooden joists why can you not fit in block and beam floor again it would be better than introducing wood .

 

[curtly]

If you can fit in wooden joists why can you not fit in block and beam floor again it would be better than introducing wood .

That's a very good point, I'll speak to the builder...

 

[Dumbo]

That's a very good point, I'll speak to the builder...

If it's not built yet it can be done as it's all about the ground work. I can't imagine there is a tiler on here that would prefer to tile to timber suspended floor instead of solid screed .

 

[J Sid]

start with a level subfloor
glue 50mm ProWarm™ XP-PRO Insulation Board - Electric - Insulation Boards - http://www.theunderfloorheatingstore.com/insulation-boards/electric/xp-pro-insulation-board
then glue
ProWarm™ 18mm Low Profile Solid floor panels - Water - Insulation Boards - http://www.theunderfloorheatingstore.com/insulation-boards/water/prowarm-18mm-low-profile-solid-floor-panels
fit pipes
Ditra
tile
finished floor height 80mm

 

[curtly]

Thanks for the responses guys, lots of food for thought.

Its looking like a toss-up between the Nu-heat LoPro Max with a low profile screed finish and the ProWarm solid floor panels.

I like the idea of the Screed finish for conductivity and being fully sealed base but reckon the solid panels would add a bit more rigidity

 

[Chalker]

Nu heat Lo pro max. Has the best kW per m2 for a 25mm total build up.

In this case, though. I would recommend an odd apraoch!!

Firstly I would bin the timber joists and fit a block and beam floor.
Set the level of this floor 160mm down from finished floor level . Fit 100mm insulation as per building regs.
Then for the existing floor ( bear with me) I would fit 25mm insulation ( I know it's not perfect, but it's the best that can be done). This will line up with the new extension floor. Cover with membrane and fit standard wet underfloor.
55mm screed on top.

Somtimes bending the rules works. Not perfect, but works.

 

[curtly]

Nu heat Lo pro max. Has the best kW per m2 for a 25mm total build up.

In this case, though. I would recommend an odd apraoch!!

Firstly I would bin the timber joists and fit a block and beam floor.
Set the level of this floor 160mm down from finished floor level . Fit 100mm insulation as per building regs.
Then for the existing floor ( bear with me) I would fit 25mm insulation ( I know it's not perfect, but it's the best that can be done). This will line up with the new extension floor. Cover with membrane and fit standard wet underfloor.
55mm screed on top.

Somtimes bending the rules works. Not perfect, but works.

Interesting, that was my own thoughts at the start, is 55mm screed the minimum acceptable as I've got tiles to add to that 80mm ?

 

[Chalker]

50-55 is minimum for tiling onto. Speak to a screed supplier, they can add fibres to strengthen it. Then it can be reduced by a bit.
@Ajax123 on here is the forum expert on here.

 

[Dumbo]

Calcium sulphate screeds can go in thinner than sand cement screeds .

 

[Swindiff]

Gyvlon Thermio+ can go down unbonded onto insulation at a thickness as low as 35mm. I had it installed in my kitchen on top of 50mm celotex. My minimum thickness was 36mm, maximum was 52mm and average was 48mm. More than pleased with it and extremely responsive to the heat in the UFH pipes. I can start to feel it coming through the floor in less than 30 minutes with porcelain tiles laid on top. I had heard all the stores of UFH having to be run pretty much constantly because it takes forever to heat up and cool down, not with this stuff, my UFH gets turned on and of as I would have with the radiators.

Gyvlon Launches New Thermio+ Screed; EasyFlow to Supply Nationwide | EasyFlow - http://www.easyflow.org.uk/news/thermio-screed/