Retro fitting external insulation on garden room

[freddiemercurystwin]

He just wants to insulate his shed a bit woody he's not building a house.

 

[cjames1984]

Me too.

It may be better to post a photo of the frame, to show what going on there.

Herea a shot of the outside and inside to give you a better idea. It's just overlapping timber, no cavity or existing insulation

 

[JohnD]

Oh, it's what my local supplier calls a "log cabin"

Each of the wide planks has a large notch near the end, so the transverse and longitudinal planks are laid alternately, and interlock at the notches.

In US, the timbers sometimes also have a tongue and groove, so each locks into the one above and below. This also prevents draughts.

I think external cladding would spoil the intended appearance.

 

[cjames1984]

Oh, it's what my local supplier calls a "log cabin"

Each of the wide planks has a large notch near the end, so the transverse and longitudinal planks are laid alternately, and interlock at the notches.

In US, the timbers sometimes also have a tongue and groove, so each locks into the one above and below. This also prevents draughts.

I think external cladding would spoil the intended appearance.

To be fair log cabin would have probably been a better description.

The main reason to insulate is to help retain the heat but there also a couple of joins starting to fail so I wanted to add a second layer of protection.

 

[^woody^]

Yes. Words matter

Do as you propose in the OP.

Bear in mind that insulation wont magically make an unheated room warm, and the air leakage from that room will be off the scale.

You are unlikely to get much benefit from anything more than a token 25-50mm of insulation, and be mindful of spending too much and getting no return

 

[foxhole]

Why do you need it heated? Whats the heat source?

 

[freddiemercurystwin]

If going the Kingspan route I would fit the foil face facing inwards, then the breather membrane on the face of the insulation then your vertical battens.

 

[cjames1984]

Yes. Words matter

Do as you propose in the OP.

Bear in mind that insulation wont magically make an unheated room warm, and the air leakage from that room will be off the scale.

You are unlikely to get much benefit from anything more than a token 25-50mm of insulation, and be mindful of spending too much and getting no return

Which part of the OP would you propose. The PIR or rockwool?

I appreciate I would need a heat source, it's likely to be a an electrical heater of some sort. As I have battery storage and cheap night rate that will significantly lower the cost.
I was just hoping to retain some of the heat with insulation.
What do you mean by air leakage?

I was originally planning for 75mm. Please could you explain why I would be better of with just a small token amount?

In the current climate and the cost of building works, I've resigned myself to not being able to afford an extension.
So in the grand scheme I can gain an additional room likely to cost under £2500.

 

[cjames1984]

Why do you need it heated? Whats the heat source?

The main reason for heating is during the colder months.
It's likely to be heated by an electrical heater of sorts. This will run on cheaper night rate electricity and excess solar.

 

[cjames1984]

If going the Kingspan route I would fit the foil face facing inwards, then the breather membrane on the face of the insulation then your vertical battens.

I did wonder about this, that way the foil layer would be better at reflecting the heat back in. The only thing i thought is I would not be able to tape the foil side. Would you still tape the backs of the panels?