Retrospective shed insulation

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Woody2Shoes

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Hi Carlos,
what will be the actual use of the shed? You say it's attached to a pub, but....For example, you plan to heat it - with what type of appliance? Will there be any other sources of heat/moisture e.g. washing facilities?
A lot of condensation probs are actually caused by the occupants and their actions.

Your barrel boards are in effect a 'rain screen' and you can expect them to get wet through in an exposed situation or if water from the roof/eaves is not fully dealt with. Therefore these cladding boards will need to be able to dry out (from both inside side and outside side) so their inside will need to be ventilated.
Don't forget that OSB usually needs to be installed with a 3mm gap all round. I do not 100% buy the argument that OSB is vapour impermeable - it certainly has a lowish vapour permeability, but is not impermeable. Any insulation will cease to function as such if it gets saturated with moisture - rockwool has an advantage in that it can dry out quite quickly because it is (if uncompressed) very vapour permeable.
There is no ideal solution given your constraints.
 
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Carlos0371

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Another thought.

How about no insulation.

When you put the OSB board on your creating a sealed unit which in and of itself will insulate. Of your working in the shed an oil filled rad and your body heat will warm it.

Or what about foil bubble wrap it's what the camper van community use.

Cheers James
Foil bubble wrap was another consideration, but opinions again are very divided on how insulating it really is, as opposed to just reflecting the heat back in and the cold back out.

Regarding no insulation, I'd hate to do that then it be effing freezing and need to pull the OSB off and sort it later.
 

Carlos0371

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Hi Carlos,
what will be the actual use of the shed? You say it's attached to a pub, but....For example, you plan to heat it - with what type of appliance? Will there be any other sources of heat/moisture e.g. washing facilities?
A lot of condensation probs are actually caused by the occupants and their actions.

Your barrel boards are in effect a 'rain screen' and you can expect them to get wet through in an exposed situation or if water from the roof/eaves is not fully dealt with. Therefore these cladding boards will need to be able to dry out (from both inside side and outside side) so their inside will need to be ventilated.
Don't forget that OSB usually needs to be installed with a 3mm gap all round. I do not 100% buy the argument that OSB is vapour impermeable - it certainly has a lowish vapour permeability, but is not impermeable. Any insulation will cease to funtion as such if it gets saturated with moisture - rockwool has an advantage in that it can dry out quite quickly because it is (if uncompressed) very vapour permeable.
There is no ideal solution given your constraints.
Hi Woody, sorry my initial post wasn't clear; the 14 x 8 main structure is going to be a pub / TV room / summer room if you like, used for entertaining, watching footy, kids to chill out etc. The shed is a separate part that I'm going to build onto the outside of the main structure, but at a later date.

I'm hoping to put in a small wood burner, which eats into my budget considerably. The whole reason for having a tight(ish) budget rather than being a bit more extravagant is that we are only renting, and obviously run the risk of having to move at any time, although the landlords have made it clear they want us here long term.

No other heat sources, but people will obviously create their own problems moisture wise.
 

Woody2Shoes

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I think that you'd be best with just 11mm OSB3 on the inside and no insulation. Just about any log burner once fired up will make it too hot even on a cold night!
 

NickVanBeest

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Renting as well, hence my shed is modular panels, 90cm wide, bolted together, each panel insulated as a whole... not ideal, but it works, and will be easy to break down and take with me :cool:
 

Woody2Shoes

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I think it would be a waste of money - I'd put the effort into detailing the ventilation. As I say, this shed is not large and will be easy to keep cosy with the woodburner, cheers, W2S
 

Carlos0371

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I think it would be a waste of money - I'd put the effort into detailing the ventilation. As I say, this shed is not large and will be easy to keep cosy with the woodburner, cheers, W2S
OK Woody thanks. Would appreciate the views of anyone else who concurs with this opinion?
 

mikej460

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Given you are going to install a wood burner I would focus on keeping damp, cold air out so a relatively cheap roll of foil insulation which if overlapped by 100mm and taped with aluminium foil would be your vapour barrier. You can then line with whatever you can afford. If your budget allows you could get slabs of much cheaper polystyrene insulation to fit between the struts. If you search this website there are some useful videos Timber Frame & Foil Insulation | YBS Insulation

I've used YBS Superquilt extensively when drylining our old cottage but this is over the top for what you need so take a look at their other products.

Don't forget ventilation and a carbon monoxide alarm for the burner.
 

Fitzroy

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Sound reasoning there Fitz, just really not keen on extending all the framework by another 2 inches either side all around, due to the additional work / cost involved. RWA45 is also prohibitively expensive to my budget. Trust me I've looked at all the options on this, and because of my gaps being various sizes (465, 550, 620, 700mm are just some of the random spacings) I'm really trying to negate waste as much as possible, which I imagine is going to mount up considerably with the batt stuff.

I'm just trying to clarify your details, do you mean install breathable membrane in the gaps between the frame leaving a 25mm gap between that and the OUTSIDE boards? This would be quite fiddly to make sure the membrane stays taut between the frame wouldn't it?

How about using polystyrene insulation as someone has mentioned to me instead?

Also, venting each partition could prove awkward as well, as to vent every partition would require 7 vents each side, and 4 on each of the end panels.

Yes a gap to the outside boards. It would be fiddly but a lower cost compromise. RWA45 varies lots in cost I’m looking at about £4.5/m2, rough calcs you have 45m2 of wall and roof area, so £200 on insulation, 100mm loft insulation is about £125. I think the loft insulation would be a false economy as it’ll slump over time and I’d be doubtful on its performance. I’d likely choose no insulation as a preference.

Regard vents, if you did insulate with a gap. Only in the roof. The outer boards will have gaps that will offer sufficient ventilation to the wall cavities. The roof layer will be impermeable, so will only dry through ventilation.

Regards experience heating an unisulated shed. My shed/workshop has yet to be insulated, walls are stud work, 18mm osb, breather membrane, battens, 15mm larch cladding (said it wasn’t mikes way) roof is 18mm osb and EPDM. It has soffit vents fir a cold roof design, eventually, so is well ventilated. A 1.5kw fan heater gets it up to 15degC after a couple of hours. A 5kw wood burner it would be toasty, oh it’s 20’x10’.

Fitz.
 

Carlos0371

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Given you are going to install a wood burner I would focus on keeping damp, cold air out so a relatively cheap roll of foil insulation which if overlapped by 100mm and taped with aluminium foil would be your vapour barrier. You can then line with whatever you can afford. If your budget allows you could get slabs of much cheaper polystyrene insulation to fit between the struts. If you search this website there are some useful videos Timber Frame & Foil Insulation | YBS Insulation

I've used YBS Superquilt extensively when drylining our old cottage but this is over the top for what you need so take a look at their other products.

Don't forget ventilation and a carbon monoxide alarm for the burner.
Thank you, I'll take a look.
 

Carlos0371

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Yes a gap to the outside boards. It would be fiddly but a lower cost compromise. RWA45 varies lots in cost I’m looking at about £4.5/m2, rough calcs you have 45m2 of wall and roof area, so £200 on insulation, 100mm loft insulation is about £125. I think the loft insulation would be a false economy as it’ll slump over time and I’d be doubtful on its performance. I’d likely choose no insulation as a preference.

Regard vents, if you did insulate with a gap. Only in the roof. The outer boards will have gaps that will offer sufficient ventilation to the wall cavities. The roof layer will be impermeable, so will only dry through ventilation.

Regards experience heating an unisulated shed. My shed/workshop has yet to be insulated, walls are stud work, 18mm osb, breather membrane, battens, 15mm larch cladding (said it wasn’t mikes way) roof is 18mm osb and EPDM. It has soffit vents fir a cold roof design, eventually, so is well ventilated. A 1.5kw fan heater gets it up to 15degC after a couple of hours. A 5kw wood burner it would be toasty, oh it’s 20’x10’.

Fitz.
Thanks Fitz for the clarification. More things to consider, so thanks again for taking the time.
 

Inspector

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It's kind of in the landlords best interest that you do a proper job on the shed and to that end credit some of what you spend off the rent. Now if this is being done without permits, inspections or planning approval, whatever you call non conforming, and be subject to removal if found out then he/she is under no obligation and might be liable for removal costs down the road. If the structure had been built like we do here, not MikeG approved, ;) OSB outside on the 2 x framing, breathable membrane and then sided, you could have insulated, put up plastic vapour barrier and then drywalled the inside. If mine now I would put vents at the top and bottom of the stud cavities, put styrofoam sheets right across the inside of the walls, caulking, taping, or foaming the edges and then drywall (maybe the waterproof kind for bathrooms) the inside. As a renter I would have just parked a trailer / caravan and played in it. You can take it with you or sell when you move. Good luck whatever route you take.

Pete
 

Carlos0371

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It's kind of in the landlords best interest that you do a proper job on the shed and to that end credit some of what you spend off the rent. Now if this is being done without permits, inspections or planning approval, whatever you call non conforming, and be subject to removal if found out then he/she is under no obligation and might be liable for removal costs down the road. If the structure had been built like we do here, not MikeG approved, ;) OSB outside on the 2 x framing, breathable membrane and then sided, you could have insulated, put up plastic vapour barrier and then drywalled the inside. If mine now I would put vents at the top and bottom of the stud cavities, put styrofoam sheets right across the inside of the walls, caulking, taping, or foaming the edges and then drywall (maybe the waterproof kind for bathrooms) the inside. As a renter I would have just parked a trailer / caravan and played in it. You can take it with you or sell when you move. Good luck whatever route you take.

Pete
OK, here goes:

Our choice to build so no obligation from the landlord to reduce rent,
Permission obtained so won't be any need to remove it IF we leave,
Regulations - none required for this size,
Could've, should've, would've........
Trailer / caravan, no chance as it's an enclosed rear garden with no access. It was hard enough getting the shed panels round the back through the public park, through the overgrowth and over the fence.

Thanks for your input though.
 

Jameshow

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Another thought

Look at insulation seconds on eBay there maybe some near you. Also building sites esp big housing jobs often throw out stuff they don't need.

Just a thought....

Cheers James
 

mg123

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I'd be inclined to not add insulation between the walls due to the damp risk, especially not loft type as it would slump. The foil/bubble wrap insulation added over the wall battens would help speed up the heating and also provides the vapour barrier if you follow the guidelines. You could add roof battens over that and then add the osb over the top and you've got a more cost effective option.
Another thought on heating, have you considered going down the diesel burner type? They appear to be very cost efficient and offer upto 8kw output so would get the temperature up very quickly. You'd obviously need an electrician if you're not confident in doing that work as they're intended for motor homes so use a 12 vault supply. That's the route I'm going down, i looked at getting a log burner but the diesel heaters seem to be a much better option.
 
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