Retrofit UFH above suspended concrete beam floor

[meadowlodger]

Hi,

 

First time posting so apologies if I break any rules or social norms...

 

We are looking to install a retrofit UFH system to our bedrooms which sit on top of an uninsulated/unheated garage space below.

 

Current floor buildup is:

- 150mm precast concrete beam floor

- 38mm screed topping.

 

No space to add insulation above the slab without having to raise external glazing that goes to floor so current plan is to insulate the soffit with about 150mm PIR (max. before restricting head height of garage below) and replace the 38mm screed topping with the following:

- 20mm retrofit UFH (Wunda rapid response)

- 7mm Wunda duoboard

- 11mm UFH compatible carpet underlay

- low tog Carpet

 

I appreciate that this will likely mean a less responsive UFH system as it will be heating the 150mm slab but hoping the insulation below will still retain enough heat to make the system effective.

 

Really just looking for a critique of the above plan, any thoughts or suggestions welcome.

 

[ProDave]

Insulating between and under the concrete beams will reduce heat directly down into the garage but you will still have the beam ends onto the cold garage wall

 

While I like UFH, I think this is a lot of work just to not have a radiator on the wall in the bedroom.

[JohnMo]

UFH in bedrooms is not the best solution, slow to heat up, slow to cool down. Retrofit UFH like you mentioned has to run hot also. Would do something else.

 

I had a similar UFH system in a well insulated garden room, it was rubbish, never heated well at all. ended up with a fan coil instead.

[meadowlodger]

I don't mind the radiator in the two kids rooms where the window sill sits higher but we are limited in the Master bedroom with built in wardrobes down one wall, bed and bedside tables on one and chest units on the third. Window opposite bed is full height glazing  down to FFL so no chance of getting a rad under that and don't fancy one sitting in front.

[Andehh]

Not sure UFH would work well totally well. Especially with carpet in top. That slab is a helluva thermal mass and with perimeter exposed.

 

Compromise would be going with one that has a thicker insulation bit. In our last place we retrofitted and it was 40mm thick I think? We lost it with a sort of ramp thresholds into the room.

 

Heated skirting boards? Vertical radiators?