Insulating shed for use as office (for xbox!)

[johnny8977]

Evening all.

I've been reading forms, blogs, articles and watching youtube video after video - but still not 100% on how to go about this.

I've got a well built 3mx3m shed that I intend to convert to use for my childish past-times such as football and xbox. The plan is to insulate the walls, roof and floor, plasterboard on top and then fill the plasterboard gaps and then either paint straight onto it or line with paper and then paint. There is already electric to it.

The few questions I still have are:

Should I use somehting like Celotex between the 'studs' and then plasterboard on top, or use something Eco-Airtec insulation (http://www.ecohome-insulation.com/?i=925557)?
The Eco-Airtec looks tempting as the videos make it look very simple.

Should I leave an air gap between the outside wall and the insulation? If so, is this because that would improve the insulation of the inside?

Do I need to cover the inside with a waterproof membrane first? The wood seems waterproof with no leaks.

And lastly, should I worry about moisture build up and put in some vents in the roof/top of walls? Some places seem to think I should but others suggest it wouldn't be a problem.

Sorry for any glaringly stupid questions but any help would be massively appreciated.

 

[Deluks]

How deep are your studs? What is the exterior cladding? You should leave at least 25mm air gap behind the cladding, and be sure to put in a vapour barrier after the insulation, or just use foil backed (or insulated plasterboard)

 

[johnny8977]

The studs are 70mm deep, so if I used 50mm Celotex that would leave me 20mm between the cladding and the boards. Would that be OK?

The cladding (I assume that's the outside of the shed) is wooden. From what I can see, it's been weather-sealed (the shed was sued as a sauna before we bought the house and it's completely dry on the inside).

Would this kit be enough on it's own with plasterboard on top? from looking at the video, I can attach it halfway deep on the studs leaving me at least 35mm air space. Could I then plasterboard straight on top?

Pricing up Celotex, it looks like that would be almost twice as expensive as the Eco-Airtec stuff and the Airtec looks easy enough to install.

Thanks.

 

[Deluks]

20mm is an acceptable void.
The celotex, whilst twice the cost, will be several times better at keeping the heat in. Shop around as you can pay up to twice as much in the 'sheds' than from a builders merchant or dedicated insulation supplier. You can get polystyrene sheet even cheaper still, but the trade off is that it's not as effective as the foily stuff.

 

[johnny8977]

Thanks for that. I can't find any reviews of the Airtec stuff so I'm hesitant to go with that without someones opinion.

If I went with Celotex, should I fix 20mm deep studs against the sides of each 70mm main stud and then fix the celotex to that, otherwise how would I ensure it keeps the air gap consistent the cladding?

And once that's down, do i then cover everything with the moisture sheet so will that not be needed as the celotex is foil lined? And then plasterboard on top......

 

[AronSearle]

If I went with Celotex, should I fix 20mm deep studs against the sides of each 70mm main stud and then fix the celotex to that, otherwise how would I ensure it keeps the air gap consistent the cladding?

Yes.

You will also find the celotex a bugger to cut accuratly (assuming your shed has square holes as well and isnt a bit skewed), so dont try to cut them to fit and instead use expanding foam, the 20mm studs will help ensure this doesnt then expand into the cavity.

And once that's down, do i then cover everything with the moisture sheet so will that not be needed as the celotex is foil lined?

The concern with a proper house is that the moisture will still go through the studs, so you should still have a VCL, but you won't be producing much moisture so it may be reduandant. However you can lap this sheet at walls/floors/ceilings, making the whole thing much more airtight, which in itself will help keep the place warmer.

 

[johnny8977]

So, can I check if I have this right.

- attach 20mm 'side studs' against each main stud, attach the celotex and fill the gaps with expanding foam.

- cover with vapour sheet

- attach plasterboards accordingly

For the floor, I was thinking of laying some wood, laying the celotex underneath as per the walls and then simply laying loft floorboards.

My shopping list is like this (although I'd perhaps try a merchants first, Wickes is just easier to link to)

Celotex 50mm (http://www.wickes.co.uk/invt/190544) and perhaps some 25mm for the floor so it isn't raised too high.
Wood for the new floor 'joists' (http://www.wickes.co.uk/sawn-treated-softwood-25x38mmx24m/invt/107137/) - is this suitable?
Bog standard plasterboard (http://www.wickes.co.uk/invt/220210)
Vapour barrier (http://www.wickes.co.uk/polythene-vapour-barrier-25x20m/invt/153230/)
Do I need this tape to seal the barrier? (http://www.wickes.co.uk/polythene-dpc-150mmx30m/invt/226580/)
Flooring (http://www.wickes.co.uk/chipboard-loft-storage-panels-pk3/invt/116420/)

Missing anything?

Thanks guys.....

 

[gwernybwch]

Pricing up Celotex, it looks like that would be almost twice as expensive as the Eco-Airtec stuff and the Airtec looks easy enough to install.

For Celotex / Kingspan etc have a look at 'Seconds & Co' website or ebay listings, as they often sell off insulation cheaply.

 

[Guitar_man]

So is 50mm celotex going to make a big enough noticeable difference to the 'perceived' internal warmth/heating costs/u values compared to say 100mm if you were to fit it?

 

[johnny8977]

I presume so. Any larger and I wouldn't be able to have an air gap and since the studs are 70mm deep, any bigger would mean coming away from them.

 

[Guitar_man]

Yes, I've heard the foil celotex is good stuff, from a mate who did his whole house in it. I've not used it myself, but I hope to use it to insulate a single skin brick walled bathroom, I'll be using 70mm, so ir'd be interesting to see how much of a difference it makes.