How to insulate log cabin?

[ontljoshi]

I want to insulate my log cabin as economically as possible and would like to keep it warm as much as possible for 6 to 8 hours between 15 to 20 degrees.
My log cabin is 4mX4m and the tallest point is 260cm ( 2.6m). So I guess the side walls are 2.4m. it doesn't have studs except on the roof. With all your help and guidance, I want to know what sort of material I will need and in how much quantity. As mentioned I would like to achieve as economically possible as like everyone I have a limited budget. I originally started looking for insulation on Facebook, freecycle, etc but it would cost me a lot in additional materials.

From the forum someone suggested below :
plasterboard
vapor barrier
insulation
breathable membrane

how ever my log cabin is single-wall wood logs locked onto each other. I guess everyone knows what log cabins are.

I would like to use the minimum number of items. like if I could use Insulated plasterboards then do I need a breathable membrane? how many insulated plasterboards should I use and which one? what else do I need?

So, if the forum can help me I would be grateful to you and your experience.

 

[Dereekoo]

By economical I assume you mean cheap, cheap means you get what you pay for and it all depends on what standard of insulation you are aiming for.

 

[ontljoshi]

Ha ha... economical doesn't mean cheap, but not dearer to the pocket... as long as it can retain heat for a 6-8hrs on Cold days. also not sure what quantity and how much material I would need. Please correct me if 50mm insulation won't be good enough for this.

 

[foxhole]

If it adequately ventilated should not need a dehumidifier .

 

[Dereekoo]

Ha ha... economical doesn't mean cheap, but not dearer to the pocket... as long as it can retain heat for a 6-8hrs on Cold days. also not sure what quantity and how much material I would need. Please correct me if 50mm insulation won't be good enough for this.

You didn't say economical design that's different to economical insulation, but in answer to you question. On a cold day,? how cold, retain the heat for 6 - 8 hrs? it will never retain the heat there will always be leakage. its a question of what ambient temp you want. Imagine you are happy with 10C and its 11C outside, it aint going to leak that much that quick so doesn't need that much heat input, now if you want 25C and its -5c outside its going to leak out quite substantially and heat input will need to be higher. All sorts of magic calculations can be done based actual cabin construction and attained U values of the walls and roof incorporating inside/outside temps. 62.5mm Kingspan K118 is a good starter for 10 but it aint cheap. I guess what you need is someone who has done something similar and can give you an empirical assessment of their work. Good Luck.

 

[Dereekoo]

Its not the same but it gives you more food for thought

https://community.screwfix.com/threads/detached-garage-insulation.232338/

 

[IT Minion]

The more insulation you put in the less heat you need to keep supplying to keep the shed warm.

So if you need to run a 3kW fan heater continuously to keep the room at 18 degrees, with a bit of insulation you'll only need to run it half the time. With more insulation it might be a third of the time and so on. So how much insulation you need depends on how little heat/power you want to use.

Thankfully a lot of this you can try and find out. 50mm insulation is a good start, try insulating the shed with that much but not finishing the inside. Then sit in it for an hour one evening to see how long it takes to get to temperature and how long it takes for it to get cold enough you'd want the heat back on.

 

[ontljoshi]

I have updated my question...you are right but being a layman and having kids to juggle with their demands don't have a lot of time also don't have electrics in place too... so along with insulation, I will be running cables too. then get an electrician to connect/terminate the mains in the house... trying to do it on my own as some of you have done. I wish It could have been a leisure project... but it is out of necessity.

 

[IT Minion]

Talk to your electrician first, some of them insist on doing the wire runs themselves because of the terms of their certifications and insurances.

The breathable membrane is to keep external water, and water that leaks through your wood walls, out. It's the same stuff you have under your roof and for the same reason.

I wouldn't go for insulated plasterboard. They're heavier to lug around than buying insulation and plasterboard separately. And normally more expensive.

If you use foil backed plasterboard then that foil acts as your vapour barrier. You need to tape up joints with aluminium tape but that simplifies things.

 

[ontljoshi]

Do I still need to use a breathable membrane? what other material do I need?

 

[Handymanjo]

Remember to allow for the expansion and contraction of the timber of the Cabin. I have seen sockets pulled of the timber when the wood shrinks during the summer.

 

[ontljoshi]

Talk to your electrician first, some of them insist on doing the wire runs themselves because of the terms of their certifications and insurances.

The breathable membrane is to keep external water, and water that leaks through your wood walls, out. It's the same stuff you have under your roof and for the same reason.

I wouldn't go for insulated plasterboard. They're heavier to lug around than buying insulation and plasterboard separately. And normally more expensive.

If you use foil backed plasterboard then that foil acts as your vapour barrier. You need to tape up joints with aluminium tape but that simplifies things.

Hi IT Minion

what are the best and economical insulation?

 

[IT Minion]

PIR very effective, which means you don't need it to be as thick. It comes in sheets and I find it easier to work with. But it's expensive.

You can use Polystyrene of some sort, which is cheaper but less effective so you'd want to go thicker.

Rockwool is cheap and available everywhere, but for that you would need separate vapour barrier and breather membranes. It'd mean more work for you, but it would be cheaper.

For both keep an eye on Facebook market, Gumtree and Freecycle. You often find people with either excess sheets or offcuts that you can get cheap.

 

[oldbutnotdead]

What internal finish are you planning on the walls/ceiling? Rockwool as an insulator is cheaper per square metre but you'll lose more space (250mm from each wall so on a 4m x 4m shed you'll lose nearly 4 square metres of internal space). Rockwool is better at reducing noise emissions (if that's important to you).
Also with rockwool you'll need a structure (studs, 2 x 2 minimum) to hold it in place and something covering the inner surface (otherwise the stuff will just fall out).
PIR boards are expensive (I'd suggest 100mm) but don't need the studs etc. The foil-faced stuff you could just wallpaper if you can live with walls that you can't fix anything to.

 

[ontljoshi]

What internal finish are you planning on the walls/ceiling? Rockwool as an insulator is cheaper per square metre but you'll lose more space (250mm from each wall so on a 4m x 4m shed you'll lose nearly 4 square metres of internal space). Rockwool is better at reducing noise emissions (if that's important to you).
Also with rockwool you'll need a structure (studs, 2 x 2 minimum) to hold it in place and something covering the inner surface (otherwise the stuff will just fall out).
PIR boards are expensive (I'd suggest 100mm) but don't need the studs etc. The foil-faced stuff you could just wallpaper if you can live with walls that you can't fix anything to.

Thank you! not sure how much material I would need for either of them and what else would be needed is the question so I can plan the budget. I am a pretty layman in all this... working things out based on various forums for this work as aiming to keep the cost low.