insulating wooden outbuilding?

[marmic]

morning all,

 

We have various types and sizes of insulation left over from our passivhus build (cut-offs and a few full sheets where we had to buy packs).  Before trying to flog on ebay or give away thinking about insulating between rafters on one of our stables we use as a daytime room for humans, storage, and dog kennels.  We had been racking up the electric bill heating with oil filled radiator whilst dogs were in there and we were in caravan (but in house now 😀) - but for convenience we'll still use as kennels occasionally and still for human use during 'horse time'. So would be nice to keep slightly warmer in there!   The questions I'm asking myself is whether  1.  will just partially insulating actually make any difference?  2.  will I create a damp problem?   It's a very un-airtight space.  And roof is just osb sarking and bitumen corrugated. walls timber stud with shiplap on outside and osb internally - definitely won't be insulating walls - not practical and will create damp!   opinions (usually plenty on here!) would be appreciated please.....  hagwe     

[Redbeard]

4 hours ago, marmic said:

will just partially insulating actually make any difference? 

 

When you say 'partially' do you mean 'the roof, not the walls' or 'only some of the roof'? The former I'd say is OK, but if 'un-airtight' means 'breezy as owt' it probably won't gain you a great deal. If you do propose to  insulate the roof can you get to the gables to drill ventilation holes in the gable at each end (you'll need a good few between each pair of timbers)?  For minimal structural diminution you ought to drill on the centre line (75mm if they are 150 timbers, for example) but that limits the insulation you can get in. It could still allow 50mm though which (crudely) could drop the U value from say 2.0 to say 0.5W/m2K, roughly adjusted for the 'thermal intrusion' of the timbers. If you are pumping in heat it will reduce the heat loss. If you are expecting it to keep you discernibly warmer on a cold day with the only heat input being the c100W of you I doubt you'd feel a huge difference.

[Iceverge]

Assuming your outer OSB layer isn't taped diligently etc I would included a seperate airtightness membrane on the inside the purlins/studs. 

 

Otherwise the OSB will be colder behind added insulation and it'll attract condensation. 

 

Also controlling the air movement will be by far and away the biggest win regarding comfort.

[marmic]

thanks for comments -   I was probably hoping for an easy fix / ideas / something I hadn't thought of!  Conclusion:   Unless I make this more time consuming and ventilate between purlins there's going to be the invisible damp/rot. Then unless I add vapour barrier too and seal it up just introduces just more cold air into the space!  To do it properly then have to work around electrics etc too and move lighting - possibly all for little gain as walls not insulated and just a stable door!  Be easier to build an insulated 'shed space' from scratch - which I'm not doing so decision is to flog the leftovers (perfect for garden office!) or give them away if no buyers......