UHF loop for attached garage

[Lewis88]

I have a large attached garage in my plans and I will be looking to lay my best in the new year. I have toyed with the idea of leaving it unheated however it will negatively affect the heating of the house as above the garage are two walk in wardrobes from two of the master bedrooms. 
 

I’m still trying to decide whether or not to lay under floor heating pipes in the screed to match the rest of the house. Are there any UFH manifolds that you can safely switch off a loop long term? 
 

i’m not even sure how I would feed it heat yet but I will have solar PV but I wouldn’t be adverse to fitting solar thermal later on down the line on the south facing roof of the dormer. 
 

what are peoples opinions on my options? And would you add the pipes in anyway - even with them potentially never being used? I’d guard to look back and not fitted a few hundred quid worth of pipe that could have been really useful. 
 

roof space isn’t an issue, I should have plenty even for the tallest of cars.

[JohnMo]

Your ceiling of the garage should be well insulated, any additional insulation here is money well spent. Having UFH in the garage is plain (sorry to be blunt) daft. You may as well through £2 in the bin each time you walk past it. Any heat added would just heat the ground - not the garage space.

[Conor]

Unless the floor slab and walls of garage are insulated, no point. 

 

If you can foresee a use of the garage in the future that would benefit it being able to be easily heated, and kept warm in the winter, then change the design to incorporate insualtion. Putting a UFH loop in the screed/concrete will cost pennies. If it's filled with inhibited glycol, no harm in it sitting dormant for periods. NB building control implications of you make the garage part of the thermal envelope of the house.

[Lewis88]

@JohnMo and @Conor the floor will have 200mm of insulation on top of a raft foundation with UFH in 50-70mm of screed. The walls will likely be 200mm full fill mineral wool batts.
 

I agree that it’s going to cost a lot to heat but I don’t want to regret not doing it especially as I may find an alternative way to heat it (if funds allow, such as solar thermal). Like Conor said, it could potentially be converted at a later date to habitable space so I want to make sure that I make wise decisions rather than regret in action. The ceiling of the garage will be very well insulated and plan was to keep it separate (other than the foundations).
 

I know it will never be as warm as the rest of the house, nor does it need to be. I have at least two cars that are used daily and will likely bring a bit of heat to the garage once parked. 

[Lewis88]

I will also be having a log burner at the other end of the house so I was contemplating whether or not the UFH for just the garage could be connected to this but I don’t think it could due to its distance from the garage (13m). 
 

if I could this would be perfect as I’d only want the garage heated in winter when the log burner is lit. However I really can’t see any feasibility in getting this to work due to the above. 

[Mike]

4 hours ago, Lewis88 said:

it could potentially be converted at a later date to habitable space so I want to make sure that I make wise decisions rather than regret in action.

It would be possible to put the loops in the floor and blank them off. But if you were to connect them, then the entire garage would have to meet normal Building Regs thermal insulation standards, including air pressure testing, to be legal. That would involve fitting a very expensive insulated and weather-sealed garage door.

 

4 hours ago, Lewis88 said:

the floor will have 200mm of insulation on top of a raft foundation with UFH in 50-70mm of screed.

I wouldn't want to park a car on a 50mm screed over insulation. I'd want a minimum of 100mm reinforced concrete.

 

[jayc89]

For a garage I'd be using concrete with rebar, tie your UFH pipes to the rebar, and forget about the screed. You can always turn those loops off at the manifold if you find they aren't needed/costing too much. 

[Lewis88]

I think that I will just be better off keeping the garage outside of the thermal envelope, leaving out the insulation in the floor and screed layer. That way i could always add it in and put UFH coils in the screed at a later date.
 

On a plus side, I also get a bit more head space in the garage from the insulation and screed that was planned for the floor. I’ll still be insulating all of the walls and ceiling though