Advice please - Electric UFH on new suspended timber outbuilding

[Danv]

I am in the process of building a timber building in the garden and am looking into electric UFH instead of an electric heater.

 

For context, the building is a suspended timber frame on 16 individual concrete blocks.

 

I currently have 100mm Celotex insulation between joists and have placed 11mm OSB3 on top to give me my flat floor. I then plan to use laminate flooring on top.

 

What are my best options here…

1 - do/can I lift up the OSB and place the UFH directly on the celotex insulation and screed over?

2 - do I install on top of the OSB and then screed?

3 - do I need to add another insulation board on top of the OSB and then the UFH with screed?

 

Any advice would be greatly appreciated!

 

Regards,

Dan

[PeterW]

Don’t use screed - you can get foil UFH designed for laminate. 

[Bitpipe]

For our bathrooms we put a 6mm insulated board on top of the OSB, laid the wire mat on that and covered with 4mm ish self levelling latex compound. Provided a nice flat surface for tiling but would have suited laminate also.

[Nickfromwales]

1 hour ago, Danv said:

I am in the process of building a timber building in the garden and am looking into electric UFH instead of an electric heater.

 

For context, the building is a suspended timber frame on 16 individual concrete blocks.

 

I currently have 100mm Celotex insulation between joists and have placed 11mm OSB3 on top to give me my flat floor. I then plan to use laminate flooring on top.

 

What are my best options here…

1 - do/can I lift up the OSB and place the UFH directly on the celotex insulation and screed over?

2 - do I install on top of the OSB and then screed?

3 - do I need to add another insulation board on top of the OSB and then the UFH with screed?

 

Any advice would be greatly appreciated!

 

Regards,

Dan

If this is for space heating, forget the electric UFH as it’ll be quite crap under laminate for one, and eye-watering in terms of running costs. You’ll have to switch it on ages before going in to use the room too. 
Get a cheap A2A heat pump, something like THIS and it’ll give you heating in the winter PLUS cooling ( air con ) in the summer. The CoP should be around 3, so for every £1 of electric you buy, you’ll get £3 of heat energy output.

It'll also be nigh-on instantaneous heating of the air, so no need for long warm-up periods before use.

Electric UFH 👎. You will regret that choice I promise you. 
What is the level of insulation for walls, and roof? 

If not the heat pump, then do yourself a MASSIVE favour and fit electric convection wall heaters. You really need to be heating the air, not the floor. 
11 OSB is very thin to go onto insulation btw., even with the laminate atop. . Point compression will be an issue, eg if you install furniture / floor standing racking shelving etc. 

Edited March 28, 2022 by Nickfromwales

[Danv]

2 hours ago, Nickfromwales said:

If this is for space heating, forget the electric UFH as it’ll be quite crap under laminate for one, and eye-watering in terms of running costs. You’ll have to switch it on ages before going in to use the room too. 
Get a cheap A2A heat pump, something like THIS and it’ll give you heating in the winter PLUS cooling ( air con ) in the summer. The CoP should be around 3, so for every £1 of electric you buy, you’ll get £3 of heat energy output.

It'll also be nigh-on instantaneous heating of the air, so no need for long warm-up periods before use.

Electric UFH 👎. You will regret that choice I promise you. 
What is the level of insulation for walls, and roof? 

If not the heat pump, then do yourself a MASSIVE favour and fit electric convection wall heaters. You really need to be heating the air, not the floor. 
11 OSB is very thin to go onto insulation btw., even with the laminate atop. . Point compression will be an issue, eg if you install furniture / floor standing racking shelving etc. 

 

Thanks Nick for the really informative response! Lots to digest here :).

I'll certainly double up on that OSB floor then, I didn't realise it was too little.

I'll have a think about that unit, only concern is it's a little ugly on the back. But cost benefits will probably outweigh that concern. Normal electric wall heater was my back up option, just liked the idea of UFH.

 

Level of insulation on walls is 50mm & Roof 50mm.

[Nickfromwales]

16 minutes ago, Danv said:

Level of insulation on walls is 50mm & Roof 50mm.

Quite low tbh, plus the cold bridging of all the joists / rafters. 

You can get through-wall AC units which are 'all-in-one', and may be more sympathetic to look at from the exterior / neighbours PoV etc.

[Bitpipe]

18 minutes ago, Danv said:

 

Thanks Nick for the really informative response! Lots to digest here :).

I'll certainly double up on that OSB floor then, I didn't realise it was too little.

I'll have a think about that unit, only concern is it's a little ugly on the back. But cost benefits will probably outweigh that concern. Normal electric wall heater was my back up option, just liked the idea of UFH.

 

Level of insulation on walls is 50mm & Roof 50mm.

 

Agree with Nick (obvs) - we only use our electric UFH in the bathrooms to take the chill of the tiles. Do you have space on the roof for a few PV panels to contribute to running the system?