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Post by mellow on Nov 25, 2023 19:20:34 GMT 1
Good evening all🙋♂️
So - I am finally getting my concrete sectional shed roof changed in the next few weeks🤞
It will have rafters fitted, then board then epdm rubber, which according to most roofers and most people ive spoken to is , and i quote " S@#t mate‼️"🙄
I'm aware a couple of you have it fitted.
My question is what have you done with the roof in relation to insulating it?🤔
I have been watching videos, and a warm roof is out of the question, so I was going to use celotex or Kingspan in-between the rafters, but leaving a gap between the top of the insulation and the bottom of the board. Apparently there should be ventilation through this gap to stop condensation rotting the rafters and board?🤔
What have you guys done?🤔
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Post by chrisg on Nov 25, 2023 19:42:39 GMT 1
Is it possible to fit Rockwool (fibreglass) insulation, same as house loft insulation. Maybe cheaper.
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Post by steve h on Nov 25, 2023 20:35:39 GMT 1
I have seen roofs sprayed with a foam. was told it was for insulation and to stop any condensation. Dont know what is was called.
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Post by mellow on Nov 26, 2023 11:24:10 GMT 1
Is it possible to fit Rockwool (fibreglass) insulation, same as house loft insulation. Maybe cheaper. It would be, but i'd need to board under the timbers to hold it up there and would still leave the question of should I leave the air gap for ventilation  |
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Post by mellow on Nov 26, 2023 11:24:47 GMT 1
I have seen roofs sprayed with a foam. was told it was for insulation and to stop any condensation. Dont know what is was called. Yes i have seen them spray lofts with that too  |
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Post by stusco on Nov 26, 2023 11:29:37 GMT 1
I think the spray foam insulation has a bad rep ,i try to find where i read it ,i need my loft done but there ton of shit up there 😬
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Post by dusty350 on Nov 26, 2023 11:33:55 GMT 1
A loft needs to breathe and allow air to circulate, otherwise you will get a condensation build up. Sealing it up is a bad idea
🙂
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Post by mellow on Nov 26, 2023 11:56:59 GMT 1
Luckily the question was have any of you guys insulated your shed roof and left the ventilation gap or just put the insulation right to the underside of the roof board? |
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Post by huggy76 on Nov 26, 2023 12:09:08 GMT 1
Interested to hear what you end up doing, I’ve got a sectional garage also and it is terrible for condensation this time of year.
If changing the roof sorts it i would consider doing something similar with mine. At present it has the original asbestos boards.
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Post by mellow on Nov 26, 2023 13:05:30 GMT 1
From what i have seen you need to stop the warm air inside reaching the roof. But you need vented gap between insulation and bottom of roof to stop the condensation rotting the timbers and roof board.
I know butchers built a shed and insulated the roof.
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Post by chrisg on Nov 26, 2023 15:30:32 GMT 1
A normal pitched roof breathes through the eves, you could board it up providing the upper part of the roof can breath
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Post by jessy03 on Nov 26, 2023 15:38:36 GMT 1
Insulate on top(warm roof), so loose lay a vapour control layer (1000G polythene) on top of the new plywood, mechanically fix your rigid insulation 130mm ish (celotex, Kingspan, rectacel, Ecotherm etc..) fully bond your EPDM or single ply.
I’d insulate the walls as well if possible.
If you insulate from the underside make sure you leave a ventilation gap or you may get interstitial condensation form, which will rot the roof from the underside, seen this a lot!
As for EPDM, it’s ok for your garage roof, just be careful when you install it not to puncture it, you can repair though, it will have a life expectancy of over 40 years I guess.
Jess
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Post by midlifecrisisrd on Nov 26, 2023 16:49:44 GMT 1
That's good info Darren, got this to look forward too when I build my workshop
Never thought of putting the kingspan on top, saves the ventilation issue
I'll do the walls as well but probably use good old glass wool for cost reasons
Steve
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Post by jessy03 on Nov 26, 2023 17:46:09 GMT 1
It’s the way I would it, I’ve only been doing it for 35 years 😂. I think it will still get a bit damp/condensation at times though
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Post by mellow on Nov 26, 2023 17:56:32 GMT 1
Insulate on top(warm roof), so loose lay a vapour control layer (1000G polythene) on top of the new plywood, mechanically fix your rigid insulation 130mm ish (celotex, Kingspan, rectacel, Ecotherm etc..) fully bond your EPDM or single ply. I’d insulate the walls as well if possible. If you insulate from the underside make sure you leave a ventilation gap or you may get interstitial condensation form, which will rot the roof from the underside, seen this a lot! As for EPDM, it’s ok for your garage roof, just be careful when you install it not to puncture it, you can repair though, it will have a life expectancy of over 40 years I guess. Jess Yes that's what I was trying to say👍🙂 It's just a flat sloped roof. Unfortunately it won't be a warm roof,cold roof instead. I'm not doing the job a roofer is. I am just going to limit the condensation as best I can, so will see if I can somehow leave a gap for air to flow through the rafters 🤔👍I will also be insulating and boarding the walls at some point👍😎 |
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Post by beardy on Nov 26, 2023 18:00:13 GMT 1
Is it possible to fit Rockwool (fibreglass) insulation, same as house loft insulation. Maybe cheaper. It would be, but i'd need to board under the timbers to hold it up there and would still leave the question of should I leave the air gap for ventilation My whole house is flat roofed and I have experience of not having ventilation due to the previous owners. If your going for a cold roof then you must have an air gap and ventilation between your Celotex/kingspan and the cold roof. |
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Post by beardy on Nov 26, 2023 18:03:52 GMT 1
I also bought a flame thrower 😄 and torch on felt and did some of my house and all of my sheds
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Post by jessy03 on Nov 26, 2023 18:37:22 GMT 1
I assume it’s you’re workshop in your man shed thread (I remember it), if the metal roof is 0.7mm you could just go over it - (should be as 0.5mm is generally for walls)
Timber kerb to the perimeter same thickness as your insulation
Loose lay polythene
Mech fix the insulation
Fully bond your EPDM
New fascia/gutter
If you ply it out, you might get away with 25mm fixed to the purlins?
If it’s someone you know doing it fine, if it’s a company I don’t mind looking over the quote/description, you might be paying for something you don’t need to.
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Post by mellow on Nov 26, 2023 18:55:34 GMT 1
Yes it's my manshed. No metal roof, just corrugated upvc s#@t sheets  no rafters either. As I say roofing bloke doing it. A lot less than the irish guy that turned up and quoted 6.5k!!!  |
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no rafters either.