Retrofit insulation

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steve66

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I want to renovate this shed that the college has. It has to have a new roof that I’m looking at battening and putting a tin roof on.
The felt roof is failing at ends, it also goes over the shed from side to side not down its length.
The main thing is insulation inside, I was thinking kingspan on top of internal stud then sterling (OSB) over insulation this leaving the two inch air gap between insulation and out wall.
Any input much appreciated
 

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steve66

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View of roof
 

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Jameshow

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Try and get a gutter on the eaves with the felt going into the gutter otherwise your roof / walls will rot pretty quickly...
 

mrpercysnodgrass

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Seconds and Co in Presteigne sell reject insulation boards at a great discount especially if you can pick them up yourself. The boards are perfect but they will vary a little in the thickness which is why they are rejects. They give a range of thickness of say 60/65mm. So long as you account for this they are great. My workshop goes from 1 or 2 degrees at 8am to 16 degrees by 9.30am about 11am I let the fire go out and it stays at a comfortable temperature for the rest of the day, so well worth the effort and expense.
 

steve66

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Seconds and Co in Presteigne sell reject insulation boards at a great discount especially if you can pick them up yourself. The boards are perfect but they will vary a little in the thickness which is why they are rejects. They give a range of thickness of say 60/65mm. So long as you account for this they are great. My workshop goes from 1 or 2 degrees at 8am to 16 degrees by 9.30am about 11am I let the fire go out and it stays at a comfortable temperature for the rest of the day, so well worth the effort and expense.
Got someone local that has slight seconds, thinking of using them then boarding with osb in case we need to fix anything to walls after
 

steve66

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Look at felt tiles and sarkin boarded roofs, better than a tin roof which can have condensation issues.
With the battening for the roof covering, I would kerf the back of them to allow any moisture to escape, I’ve used that method on another build. Not sure of budget that's available yet.
I know something has to be done as if you look at the end of the boards there is already damp on them.
 

steve66

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Not too far away from you mate I'm in Pembrokeshire, if you're looking for a good deal on the kingspan do you know Richard Barrnet from martletwy ? He's a nice fella & always decent on price
Think I may have his details saved on Facebook
 

steve66

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Side to side was a new way of doing it to me as well, the shed has been up a while and current lecturer doesn’t know who put it up
 

Hornbeam

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Look at felt tiles and sarkin boarded roofs, better than a tin roof which can have condensation issues.
A properly installed insulated metal roof will out last a felt tiled roof, The reason people have condensation issues is they dont follow the first principles and install correctly
 

DBC

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I have had to put a hold on my scheduled work for a week or so to fix storm damage from Friday. So my advice is if you are going to put an iron roof and guttering on - even with the smallest of overhangs - tie those trusses and purlings with steel fixings to the walls; ditto with the sole plates at the bottom (a la the building regs). An overhung roof can be grabbed by the wind in the way a boxy felt shed roof can’t. One of my customers now has his shed roof lying on his driveway with the corner on it pierced into his caravan. Although it currently looks comical he isn’t laughing at all.
 

kgill

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Hello you lovely people.
I'm relatively inexperienced with the site and I'm not sure if this is the most appropriate place to put this, but I am also trying to retrofit some insulation in my garage workshop and I was wondering if you could help? Steve66 I'm sorry if this is hijacking your thread.

I think I've worked out most things but if there are any glaring errors please let me know. The picture attached is a representation of my plan. It's a detached garage made of blocks with a tiled roof. Currently the floor is a concrete slab, the walls are bare blockwork and the ceiling is open through to the underside or the roof. I've been using it as my workshop for the last 10 years and while its been absolutely fine (if a little cramped at times) the time has come to insulate it and just generally sort everything out.

SO THE QUESTION IS...where does the damp proof/ vapour barrier/ plastic sheeting/ breathable membrane go? and what do I use? In the picture its either the red line ie on the inside wall of the garage OR the green line ie just beneath the OSB.

Any advice and or help much appreciated.

Thanks

K
garage ideas.JPG
garage ideas.JPG
 
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harryc

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Just use foil backed insulation like kingsman, that will be your vapour barrier.
Leave a gap between your wall and the insulation sheets by battening out.
And make sure you cover any thermal bridges with aluminium tape.

What you want to do is stop moisture from inside getting to your rafters plus if you are using osb that is also very good at stopping moisture crossing.

Easy Peasey 😁
 

kgill

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Just use foil backed insulation like kingsman, that will be your vapour barrier.
Leave a gap between your wall and the insulation sheets by battening out.
And make sure you cover any thermal bridges with aluminium tape.

What you want to do is stop moisture from inside getting to your rafters plus if you are using osb that is also very good at stopping moisture crossing.

Easy Peasey 😁

Thanks!!
 

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