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Shed Insulation question.....

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Stemck

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I have a wooden shed already built and was wanting to insulate it.
The batons to the shed walling give me 43mm. I have an opportunity to get some free kingspan insulation to do it, however it is 50mm thick.

Is it possible to use this and squash it down with the plywood boards I am going to put over them?
 

Doug B

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I’d rip some 9mm osb or ply down into strips the width of the battens & fix this to the battens to make up for the discrepancy, Kingspan won’t squash down.
 

Noel

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And if you manage to squish it it'll not provide as much insulation as it should. Doug has given you good advice and it's really the only option.
If no OSB/ply any scrap timber cut to size will do.
 

HamsterJam

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I’m in the process of putting 50mm Quinnboard under the floor of my shed and you can walk on it so there is no way you’ll compress it down.
If the wall behind is solid, I might be tempted to just nail or screw through into the batons as they are and accept there will be a gap between your ply and batons but that will put pressure on the wall behind which may be forced outwards over time.
I suggest your best bet is as suggested above and make up the height of the batons to 50mm and ideally a couple of mm more.
 

Westwood

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There are better alternatives to Kingspan, better as in easier to fix and thermally more efficient.
i'm halfway through insulating and cladding my 4m by 5m log cabin. Solid 44mm walls interlocking "logs".
For the wall insulation, I used Actis Boost R Hybrid stapled to horizontal 2 by 1 battens, fixed to the outside of the walls.
Its a 35mm thick multi foil product. Comes in a 10 square metre pack.
To the horizontal battens, I screwed vertical 2 by 1 and a half battens, to which I am screwing Hardieplank cladding. Result: proper insulation and no more painting of the outside. Using counter battens in this way, I get the desired air gap each of the insulation as the manufacturers recommend. Pics available if you're interested ? Cabin roof will be insulated with Actis Hybris, a compressible honeycomb product, friction fitted between the rafters.
 

Doug B

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There are better alternatives to Kingspan, better as in easier to fix and thermally more efficient.
i'm halfway through insulating and cladding my 4m by 5m log cabin. Solid 44mm walls interlocking "logs".
For the wall insulation, I used Actis Boost R Hybrid stapled to horizontal 2 by 1 battens, fixed to the outside of the walls.
Its a 35mm thick multi foil product. Comes in a 10 square metre pack.
To the horizontal battens, I screwed vertical 2 by 1 and a half battens, to which I am screwing Hardieplank cladding. Result: proper insulation and no more painting of the outside. Using counter battens in this way, I get the desired air gap each of the insulation as the manufacturers recommend. Pics available if you're interested ? Cabin roof will be insulated with Actis Hybris, a compressible honeycomb product, friction fitted between the rafters.
Whilst I'm not arguing with you the Chap stated he was getting the Kingspan free,
 

Woody2Shoes

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There are better alternatives to Kingspan, better as in easier to fix and thermally more efficient.
i'm halfway through insulating and cladding my 4m by 5m log cabin. Solid 44mm walls interlocking "logs".
For the wall insulation, I used Actis Boost R Hybrid stapled to horizontal 2 by 1 battens, fixed to the outside of the walls.
Its a 35mm thick multi foil product. Comes in a 10 square metre pack.
To the horizontal battens, I screwed vertical 2 by 1 and a half battens, to which I am screwing Hardieplank cladding. Result: proper insulation and no more painting of the outside. Using counter battens in this way, I get the desired air gap each of the insulation as the manufacturers recommend. Pics available if you're interested ? Cabin roof will be insulated with Actis Hybris, a compressible honeycomb product, friction fitted between the rafters.
In terms of insulation performance it's hard to beat Celotex/Kingspan PolyIsoCyanurate (PIR) boards (for a given thickness).
 

Spectric

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I think that PIR boards like Kingspan are better for thermal performance but are rigid boards, the Actis Boost R Hybrid insulation is flexable and so can be used in places where you cannot get a rigid board.
 

Wood&StuffLtd

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I have a wooden shed already built and was wanting to insulate it.
The batons to the shed walling give me 43mm. I have an opportunity to get some free kingspan insulation to do it, however it is 50mm thick.

Is it possible to use this and squash it down with the plywood boards I am going to put over them?
As has already been stated you need to build up the battens, place the free Kingspan insulation and before fixing the ply cover it with a vapour barrier and screw the ply on. There should be no gaps in the vapour barier and overlap the joints. I used a staple gun on the battens. If you have a drill and impact driver then use screws. Much easier to remove and repair, especially if you want to hide cable or wite later. Why the vapour barrier for a shed? Moisture will condensate on the inner surface of the outside shed wall and over time will rot weaknesses. In the wood, especially at door and window componants as joinery timber is not usually treated. Vapour barrier is relatively inexpensive. Although Kinspan is not suseptable to moisture it is the gaps at edges, top and bottom were moisture gets through, hence the barrier. Hope this helps.
 

Spectric

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Last time I used PIR boards I did not use the vapour barrier but instead used aluminium foil tape to completely seal all gaps and cover bare woodwork, afterwards I though why did I not just use a vapour barrier as it's a lot cheaper than rolls of aluminium foil tape and a lot easier!

Also if running cables in insulation you need to do the calcs to ensure they are sized right, cable current carrying capacity is derated in insulation.
 

harryc

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You don’t need a vapour barrier as the foil on the pir board is your barrier to moisture travelling out.
Just make sure you ensure there is no thermal bridging by covering the batons with aluminium foil.
Plus if you are using osb boards to cover the insulation that is another barrier to moisture.
 

DBT85

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My first thoughts were, no way are you compressing the boards.

As others already stated, build up your studs and put the boards in. The boards are most often cut with a hand saw but frankly it was much easier and faster for me to do my workshop with a cheap Evolution table saw.
There are better alternatives to Kingspan, better as in easier to fix and thermally more efficient.
i'm halfway through insulating and cladding my 4m by 5m log cabin. Solid 44mm walls interlocking "logs".
For the wall insulation, I used Actis Boost R Hybrid stapled to horizontal 2 by 1 battens, fixed to the outside of the walls.
This stuff is thermally more efficcient than PIR boards?
 

Fergie 307

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Only observation I would make is its probably not a good idea to have your insulation in contact with the outside cladding. If the insulation is not waterproof then moisture will wick into it from contact with the outside cladding. If it is waterproof and in contact with the cladding then it will cause the cladding to retain moisture for much longer than otherwise by limiting airflow. And why is everyone obsessed with OSB? Nasty stuff, as a finishing material anyway. I have used t & g chipboard flooring sheets in all my buildings as a liner. Cheaper than OSB, nice clean joints, nice smooth surface and waterproof.
 

HamsterJam

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There are better alternatives to Kingspan, better as in easier to fix and thermally more efficient.
i'm halfway through insulating and cladding my 4m by 5m log cabin. Solid 44mm walls interlocking "logs".
For the wall insulation, I used Actis Boost R Hybrid stapled to horizontal 2 by 1 battens, fixed to the outside of the walls.
Its a 35mm thick multi foil product. Comes in a 10 square metre pack.
To the horizontal battens, I screwed vertical 2 by 1 and a half battens, to which I am screwing Hardieplank cladding. Result: proper insulation and no more painting of the outside. Using counter battens in this way, I get the desired air gap each of the insulation as the manufacturers recommend. Pics available if you're interested ? Cabin roof will be insulated with Actis Hybris, a compressible honeycomb product, friction fitted between the rafters.
Pictures please Westwood.
As well as under the floor - which is work in progress and developing a story of its own, I have put 50mm PIR on top of my shed roof under felt shingles. It was very easy to fit as I just cut it to size and nailed the shingles to the roof using 65mm instead of the supplied 15mm clout nails. I dont plan to insulate the wall which in my case are 40mm logs.
Hopefully the builders merchant will come and exchange the second lot of flooring boards tomorrow so I have a matching set rather than a mix of 18mm and 22mm boards 🙄.
 

Jonm

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I am not adding much here but agreeing with the advice you have been given. As others have said, kingspam pir will not compress, it is used under concrete ground floor slabs. My concern, as others have said, would be moisture/dampness getting through the outer skin and getting trapped and rotting the wood out. Gutters and downspout to get the water away from the sides of the shed would be good. As others have mentioned a 25mm air gap between the insulation and outer skin would be a good idea.
 
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