# Retrofit insulation



## steve66 (11 Feb 2022)

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 (11 Feb 2022)

View of roof


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## Spectric (11 Feb 2022)

Look at felt tiles and sarkin boarded roofs, better than a tin roof which can have condensation issues.


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## SamG340 (11 Feb 2022)

Kingspans good stuff . If money's not a object go for the kooltherm stuff it's incredible


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## SamG340 (11 Feb 2022)

Where abouts in West Wales are you ?


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## Jameshow (11 Feb 2022)

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


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## steve66 (12 Feb 2022)

SamG340 said:


> Where abouts in West Wales are you ?


Up at Cardigan


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## mrpercysnodgrass (12 Feb 2022)

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.


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## steve66 (12 Feb 2022)

mrpercysnodgrass said:


> 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


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## steve66 (12 Feb 2022)

Spectric said:


> 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.


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## SamG340 (12 Feb 2022)

steve66 said:


> Up at Cardigan



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


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## steve66 (12 Feb 2022)

SamG340 said:


> 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


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## Woody2Shoes (12 Feb 2022)

"Side to side" is the right way to lay felt. Have you looked at EPDM? It's what I'd use.


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## steve66 (12 Feb 2022)

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


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## Hornbeam (16 Feb 2022)

Spectric said:


> 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


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## Spectric (16 Feb 2022)

Hornbeam said:


> A properly installed insulated metal roof will out last a felt tiled roof


Could not agree more but it is a cheap option for many, the corrugated is better but I went for a slate roof because it was cheaper than an insulated metal roof and does not look industrial.


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## DBC (20 Feb 2022)

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.


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## kgill (2 Mar 2022)

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


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## harryc (2 Mar 2022)

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


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## kgill (8 Mar 2022)

harryc said:


> 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.
> 
> ...



Thanks!!


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