Insulating a tin shed

[Glenn]

Hello smart people,

 

Amongst other reasons, project delays mean I need to convert a farm shed into temporary/ancillary accommodation, so that I can live on site during actual barn conversion.

 

The ancillary accommodation is a typical farm shed of about 56m2 - a very light timber frame which is semi-portal frame like, clad with corrugated iron. All sitting on a concrete pad. That's about it . I don't  have the time (or budget...) now to use  insulated metal panels, which would have been interesting, but needed a lot of work to straighten and strengthen the existing frame. Instead the plan is to reinforce the existing timber structure, introduce some light stud walling between the existing wall posts etc to allow interior cladding in plywood. What I would greatly appreciate some help on is ways I can insulate the walls and ceiling please? I am trying to avoid having to strip the building of its tin cladding.

 

Option 1 - Spray foam directly on corrugated cladding. Great airtightness and speed of work, but high cost

Option 2 - Rockwool insulation between the tin cladding and the interior plywood lining. Approx 200mm depth available

Option 3 - PIR boards between the studs

 

In both options 2 and 3 I presume I will install a VCL of some sort over the insulation before I put the plywood lining on. My dumb questions relate more to if I need anything between the corrugated iron and the insulation, whether it be walls or roof. And particularly on the roof, is any sort of air gap required? Or indeed, is there a better option? 

 

Regards,

Glenn

[Big Jimbo]

I would consider building inside the barn, and leaving the barn as it is. Timber structure 4x2, plenty of insulation in the walls and roof. No actual roof covering needed as it will ne under the tin roof. Providing it don't leak. Set on on a few blocks on the floor with a 6x2 floor. stick plenty of insulation in that as well. Build it so you can take it apart, and transfer it to the garden as a posh shed, or summerhouse.

[Gav_P]

What big jimbo said. 
 

although it might be worth having a look at the generic SIPs that are forsale on places like eBay. You could make a decent insulated box quickly and cheaply. 

[Glenn]

Good thoughts both, thank you! But I don’t think building within building will suit this particular example. Main reason being restricted height ( it’s quite squat) and also that it’s agricultural - where I want the ancillary accommodation shed is where the shed is now! If you know what I mean. I’m also quite keen to have windows and doors in the structure 

 

Any other thoughts? It’s the moisture/vapour control I’m uncertain of, no experience in it

 

Unless of course you mean inside the actual ‘barn’ I’m converting? Would prefer to avoid that, building site soon

 

Regards

glenn 

 

 

[Gone West]

Spray foam would be the best choice as it should stick to the corrugated steel as long as the surface temperature is high enough. The only problem is the cost. I'm not sure whether a thin layer of spray foam with a layer of Rockwool on top would be a problem with interstitial condensation but would be cheaper than all spray foam.

 

https://www.dupont.co.uk/products/froth-pak-180.html

 

https://www.abbuildingproducts.co.uk/froth-pak-180-spray-foam-kit-inc-9ft-hose-gun.html

 

 

[Glenn]

Thank you Peter. I agree on spray foam being the best choice, but the cost is eyewatering...

I am tending towards having as effective a VCL as possible, to minimise interstitial condensation. It's an old building - outboard of the VCL (ie the insulation and the tin cladding) it's an old enough building that moisture can surely escape!

 

Contrary advice welcomed, I am a beginner in this

 

Regards

Glenn