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My garage is part of the house (under the en suite if it matters). Getting a new insulated garage door fitted soon. Before that, I want to reroute power and lighting which means pulling down the plasterboard. I think there's some glass wool type insulation stuffed up there as well.
All sounds good but there's a small section at the front of the garage that extends beyound the floor above. I can see the felt looking up towards this bit. Thinking that if I'm doing all this work, I might as well extend the new board to cover this gap, but I'm wondering what the best sort of insulation might be? Does it matter? Could the wrong choice cause any issues? Should I just choose a solid type as its easier to work with and wedge into place?
Shameless bump!
I wouldn't go just stuffing insulation in there. If the roof void is designed to be ventilated you risk introducing condensation and rotting the timber. If it is a warm deck or cold deck the installation needs to be placed appropriately.
That's you told 😀
Hi there, am in the building trade myself so hopefully my advice should be correct!! I'm assuming that the roof in question is a lean-to fixed to the front of the house, if so just make sure there is some form of either over fascia vent or soffit vent (there should be) then insulate and plasterboard the ceiling. Board insulation will be better for over head work or use fibre if you install an access hatch.Important note, the ceiling must be plastered to comply with fire regs.
Thanks for that. The "roof" bit on the front is only a couple of foot wide if that.
In really basic terms, what we're saying then is that it will be okay so long as it has some air flow and doesn't become a sealed box. Worst case, I could add a vented tile I suppose.
I was planning on using fire rated plaster board although I'm pretty sure the existing stuff isn't.
Just had a closer look. It is vented along the full length of the soffit but nothing at the top edge where it meets the upper floor.
Don't I need a high and a low point to get the circulation it needs or will it be okay in such a small space?
It's normally just at the soffit although the rest of the roof isn't usually totally air tight. Just make sure you don't block the vents with insulation and keep a channel all the way along the void. Maybe some 50mm celotex between the joists with a 50mm void above if they are 2x4s
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Soffit vents running the full length
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Nothing at the top edge, although unlikely to be air tight
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All I can feel over there is the void between brick and block
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It's not a very big space. Seems a bit pointless really, just a great big chimney!
The joists are less than 3"x1.5"
The pitch is about 27 degrees.
That section is about 2.5m across the front of the garage.
I'm not ever expecting the garage to get really hot, it's more a case of not wanting it to get really cold. I might occasionally use the oil radiator if I'm in there working but mostly it's just the boiler and maybe the washing machine might be running.
Thanks for all the help.
Cheapest way 100/170 wool insulation.
Easiest way kingspan/celotex sheet.
Leave both resting on the wall plate to allow air flow.
I trust the ceiling you removed was tested for asbestos.... If the house is pre-90s there is a good chance it was AIB (very nasty stuff with strict rules on handling and disposal)....
If you're not bothered about the appearance then just screw sheets of kingspan to the underside of the joist and leave it like that. It doesn't need to be plasterboarded because there's no living space above that roof. If you want to keep that space open for storage then cut the kingspan down a fit into the roof making sure you leave a gap of 50mm between the felt and the insulation for air circulation. Again , it doesn't need to be plasterboarded
Sorry, it was too late to edit my advice. I didn't read your original statement properly OP( slight hangover ). Rockwool over the joists and reboard I'm afraid. I didn't realise you had already taken down the ceiling
Ceiling isn't down yet. That a a job for tomorrow. This bit is just the overhang at the front.
House was built in 1995. What's up there at the moment is green backed plaster board. I can see bits of glass fibre type insulation poking out the sides.
The artex didn't have any asbestos in it but we didn't get anything else tested.
Just double check on the HSE website that they'd stopped using asbestos board for integral garage ceilings by 1995. There's some good advice there.
Green plasterboard is moisture resistant and it's used mainly in bathroom's so it's strange to see it in the garage. If you're pulling down the ceiling under the ensuite then you should replace it with pink plasterboard (fireline) and reused the original insulation. There will be a steel RSJ or catnic lintel spanning across the garage that's supporting the front wall of the house. As long as that is covered and sealed with pink plasterboard you can leave the space in your photos open and just use kingspan as I mentioned earlier. Hope that makes sense