Where to place the wet UFH - insulated beam and block

[AppleDown]

Hello everyone! Due to ground make up, soil investigations, tree roots and cost, we've decided on an insulated block and beam foundation sitting on a concrete ring beam with piles. Litecast (specifically the GT variant) seems to be the best bang for buck, achieving 0.15 W/m²K. The EPS needs a structural concrete topping of 75mm. My question is should we look to run the wet UFH through this, or add another screed topping and have the pipes in that instead? We'll need some self leveling screed anyway to ensure a flat surface, but is there much difference in placing them in that first level?

[BotusBuild]

That sounds like a reasonable way to do it. It will work.

 

The key is whether there is enough insulation. Can you add 50mm PIR on top of the EPS and then the screed with the UFH pipes. This would increase your overall U-value and make the heating a little more efficient (= cheaper to run). Insulate as much as you can now before the screed is poured 

 

[Dave Jones]

 

id want a minimum of 300mm eps or 150 celotex

[JohnMo]

51 minutes ago, AppleDown said:

The EPS needs a structural concrete topping of 75mm. My question is should we look to run the wet UFH through this, or add another screed topping and have the pipes in that instead

Add more insulation if you can.

 

Use the 75mm as your floor and clip the UFH pipes to the insulation, prior to pouring the concrete.

[AppleDown]

1 hour ago, BotusBuild said:

That sounds like a reasonable way to do it. It will work.

 

The key is whether there is enough insulation. Can you add 50mm PIR on top of the EPS and then the screed with the UFH pipes. This would increase your overall U-value and make the heating a little more efficient (= cheaper to run). Insulate as much as you can now before the screed is poured 

 

I think that's my preference. My next questions is: would the structural concrete topping be OK to lay the actual floor on then? Do I still need some leveling screed on top? It'll be C30 with some fibres in.

 

Buildup of the floor as provided by Litecast is below (it's a timber frame, so ignore the wall detail). That's 255mm from bottom beam edge, so adding another 50mm of PIR total will be 355mm (without any further leveling screed).

 

 

[JohnMo]

20 minutes ago, AppleDown said:

My next questions is: would the structural concrete topping be OK to lay the actual floor on then? Do I still need some leveling screed on top? It'll be C30 with some fibres in.

My floor is 100mm fibre reinforced (think I did C30), paddle floated. Had a few low areas so just used self leveling screed where needed to get it level.  Wet rooms are tiles, nearly everywhere else is wood glued down, bedrooms are carpet. My floor was done before any walls were built, easy access, no walls in the way.

[BotusBuild]

If you can get the screed pourers to float it level then you might be able to lay flooring directly. Otherwise, a little levelling screed mixed as runny as feasible 🙂 to make sure it finds the dips

[AppleDown]

2 hours ago, JohnMo said:

My floor is 100mm fibre reinforced (think I did C30), paddle floated. Had a few low areas so just used self leveling screed where needed to get it level.  Wet rooms are tiles, nearly everywhere else is wood glued down, bedrooms are carpet. My floor was done before any walls were built, easy access, no walls in the way.

Lovely - thanks for the info. This might need a whole other thread, but how did you go about setting up drains for the showers/wet room?

[JohnMo]

47 minutes ago, AppleDown said:

how did you go about setting up drains for the showers/wet room?

Mine is a ground bearing slab, insulation and the concrete floor, instead of block and beam. My drainage is under the slab and brought through the insulation. Used insulation formers where drain runs under showers and bath would go to stop concrete getting there. Then once drains were sorted I back filled with concrete. Not sure if the exact logistics of drains and block and beam, but suspect similar.