Garage Conversion is Freezing!

Discussion in 'Building' started by Ben B, 23 Nov 2021.

  1. Ben B

    Ben B

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    I converted my garage a few years ago, followed all advice from the building regs officer and did everything by the book, but the room is so cold in the winter and I've had enough! Now I want to get to the bottom of it!

    The front (old garage door) has a window now, and now 150mm celotex (I added more!)
    The existing garage side wall had a cavity stud wall with 50mm celotex, and I added another 50mm celotex-backed plasterboard in an effort to fix the problem. So that should be fine.
    I've added double loft insulation, and made sure to try and tuck it into corners, as I had the feeling cold crept down corners of the room.
    (and borrowed a thermal camera too)
    I've even drilled and squirted expanding foam in places I felt may be colder than they should.

    There are two areas, as I can see it, that could be the big issues.
    Which one (or is it both?) do people think are the worst issue now?

    There's one wall, where the garage meets the house, where I was advised to dot-and-dab plasterboard directly onto the exterior brickwork of the house. Every other wall had celotex, the other single layer garage brick walls had a cavity stud wall and celotex, but he said I didn't need to there. That's wrong surely, the cold exterior wall of my house surely carries the cold? It's certainly cold to the touch.

    The floor is the other thing - I was told they were allowed to be flexible with how much insulation was needed, and it turned out that, to meet the existing floor height at the threshold to the house, 50mm of celotex, plus floorboard came to the right height exactly. Is 50mm celotex over the old concrete floor of the garage enough?

    I'm hoping the floor isn't the biggest problem - as I can't raise it! There would be a step up into the room, and the ceiling is already low. Not to mention how hard it would be to empty the room and lift the existing floor!

    I'd love to know anyone's opinions. Not sure who I could call to visit for advice. I called one company about a thermal survey but they wanted £500 to visit!!
    Thanks
     
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  3. stem

    stem

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    If by "external wall" you mean the wall that now separates the garage from the house, there isn't any need to insulate it, as it will be heated on both sides, i.e. the garage and the inside of the house. Heat is lost to colder areas, so, if the garage and the inside of the house are both around the same temperature, then there won't be any heat transfer between the two areas, which is why internal walls such as those between bedrooms, living rooms etc. aren't insulated. Having said that, if your home has cavity walls, the external wall may have insulation in it anyway.

    It sounds like you have everything you need insulation wise. Maybe the heating you have isn't sufficient, or not on for long enough periods to warm the fabric of the garage properly. If the garage is unheated for long periods of time, and for example, the temperature inside sits at 14 degrees, when the heating is put on, the air is warmed but the wall, floor, ceiling, will still be at 14 degrees and may take several hours to warm up to the temperature you want. Until it does, it's cooling the air that you are trying to heat, and you will notice the difference between the two.
     
  4. sxturbo

    sxturbo

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    What are you using for heating? If central heating, has the rad been sized correctly?

    Everything sounds right what you've done.
     
  5. tony1851

    tony1851

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    Only point I would raise is the thickness of floor insulation - normally 100mm PIR required, but understand the issue of headroom.
    As above,maybe your heating method is not upto scratch?
     
  6. cdbe

    cdbe

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    Try an online radiator sizing calculator, and check the existing radiator gets hot (sometimes add ons to an existing system aren't designed very well).
     
  7. stem

    stem

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    If you have a radiator connected to the house central heating and the heating in the garage is rarely used, you may find that when you turn on the radiator, if the rest of the house is already warm the room thermostat will be cycling just to maintain the warmth in the rest of the house and it may not provide enough heat to the garage from scratch.
     
  8. Harry Bloomfield

    Harry Bloomfield

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    TRV's on the rads, plus another stat in the garage able to work in parallel, or zoning the garage separately would work around that.
     
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  9. pilsbury

    pilsbury

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    Insulation on the floor is a little lean, but shouldn’t cause too much issues. The rest of the insulation sounds ok. The in insulated wall now sounds like an internal wall so shouldn’t need insulation.

    Most cold comes from draughts. Are you sure you have no silly gaps anywhere? Can you feel cold air coming out of plug sockets or skirting boards?

    If you stuck a fan heater in there and got it toasty, would it hold its heat for a while or cool down super fast?

    As all have pointed out, check your current heating. If it’s main central heating, check the rad is big enough, check it heats up at the same time as your other rads (balancing) and check it’s nice and hot to the touch all the way to the top (bleeding). Certainly use an online calculator - room size, windows, external walls etc added and see if it’s big enough. Even if it is and everything else is in order, just go bigger. Not necessarily height and width, maybe just an extra leaf….
     
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  11. ^woody^

    ^woody^

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    Cool post. Lol.

    You don't mention the heating though. :rolleyes:

    Is it suitable? Is it turned on?
     
  12. cdbe

    cdbe

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    It's true, we should all stop making silly assumptions.

    I've seen the OP's house:

    Screenshot_20211123-153647~2.png
     
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  13. ^woody^

    ^woody^

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    Must be loaded, he's got a merc :rolleyes:
     
  14. Tricky-Dicky

    Tricky-Dicky

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    Hi, might well be the rad(s) is undersized. How many external walls/surfaces does the garage have? Possibly 5, ceiling, front wall, rear wall, side wall, floor. Compare to a room in your house: 3, ceiling or floor, and two external walls. Additionally long narrow room ie your garage has more surface area than a square room. Far great heat loss in the garage conversion.
    Came across this at my daughters house - utility room. Long narrow room, 3 external walls, floor and ceiling - all external surfaces. The requires rad was far larger than nearly any other rad in the house.
     
  15. Ben B

    Ben B

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    Thanks all so much for the replies.
    I'm going to definitely get a heating engineer round, now I'm slightly more confident the room isn't completely 'broken'!
    There are a couple of small draughts, a couple of plug sockets, and where I've routed cables into the wall for a tidy TV installation, and they just emerge through a hole.

    I'm going to relocate that TV anyway, so will seal up anything like that. Plus there's a patio door where the doorstep feels like it might be letting in cold. Maybe another visit with some mastic (surely that wouldn't make a difference, would it?)

    Interesting that you say the room just needs more heating to expect it to then hold heat. Heating it as far as to properly give the structure some heat, I guess is difficult when it's a converted garage, as it's not like you're heating a whole house, adjacent rooms etc. I guess why people tell me their garage rooms are always a bit colder than they'd like.
    As it's an added-on room, I stupidly just Tee'd a pipe onto a nearby radiator in the house, so the water doesn't really know where to go for the best! (If I turn off the house rad the garage room gets heat, and vice versa, but not really both! - how do I get round that?) So that radiator is as good as useless, then I've got 1KW electric underfloor heating, which is usually left off, as I'm too scared I'll leave it on overnight and run up a huge bill! and a wall-mounted electric heater at the far end. Usually I leave the electric heater (and pathetic badly-plumbed radiator) giving the room some initial heat, which I guess promptly leaves the room on the next breeze!

    I need to ask an engineer how I'd properly add a radiator, change the thermostat for the UFH to one with a timer, and possibly add a second wall heater on another wall. And then not be scared to give the room some heat for a good long time if I expect it to be useable. Once I do a final search for draughts.
     
  16. jacko555

    jacko555

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    I'd stop the drafts first. Don't underestimate the cooling power of them. It's like having a window open with your (underspec) heating on. I draft proofed the kitchen (holes for services and gaps round the edge under units) and it made a considerable difference.

    I reckon still sort that rad out but draft proofing will then let the insulation work
     
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  17. rssteve

    rssteve

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    Were your cavity walls insulated? That internal cavity wall might still have cold air inbetween it even though its heated both sides.
     
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