Yes I know another insulation thread but I don’t have the luxury of building one, I’ve got one left by the previous house owner and need to improve the insulation with minimal hassle.

Main question is insulting a shed like this, that expands/contracts a fair bit and isn’t air tight, am I better insulated outside or inside, and assuming inside how do I fix insulation without constraining the wood from moving?

It’s interlocked 44mm single timber construction with pitched roof, zero insulation. It has a storage room off the back with internal door – this door opens into the main room

Wall with door and windows expands a couple of cm between the seasons, there are truss rods (or whatever they are called) at various points through the timbers but it seems impossible to fully close the gaps up at the top where walls join the roof.

Windows and doors have trims inside and out, think some drafts coming in through there, and it might be the timbers are sat on top of the frames meaning they don’t quite settle in against one another.

I am not sure I can get underneath it to do below the floor, the shed is raised on vertical timbers but not by a lot. May be that something under the carpet is the only option.

Any other ideas and things to do?

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With that I’d just do the floor and the ceiling. 40 or 50mm celotex/kingspan.

Build a log cabin?

Isn’t that just a posh looking shed?

knock it down and build a log cabin or accept its a shed / summer shed house

I can accept it’s a shed, if that is the appropriate nomenclature.

How do I insulate my shed made out of interlocking lengths of cut logs?

Seriously though I am tempted to turn it back into a shed, wait for the floor to rot through and knock it down.

What Dave said. Insulation on top of the floor. Insulation in between the rafters in the roof and you can put tongue and groove under the rafters to make it pretty.

Floor and ceiling will make that really cosy.

The double glazing is thin so you could add secondary units to the inside for not a lot but I would do the other jobs First and see what it is like.

Thanks, will start above and below and take it from there. It’s been fine as it is down to 5 or so degrees but last couple of days haven’t been so comfortable.

I have a similar designed log cabin (although mine is a bit smaller). The size of the windows despite being double-glazed will mean it’ll take a bit of heating to maintain temp in the cold.

Anyway I just stuck 50mm polystyrene block between rafters (aligned with the bottom to give an air gap above), then the bubble-wrap foil stuff below (junctions taped with aluminium tape to make air-tight). It’s all held up with 3mm plywood sheet. Didn’t cost much.

Floor is lightly insulted under the floorboards, but a layer of vinyl tiles (5mm thick) keeps the drafts out.

Didn’t bother with walls (I think they’re 40mm tick ‘logs’), I just make sure they remain locked together despite the expansion/contraction through the seasons.

Mine’s toasty warm with a 2kw oil-filled radiator on half-thermostat setting.

Structurally my office is similar but with less glass and I have secondary glazing as well. It was -11 degrees here this morning. Oil radiator was on a timer before I came in. 15 minutes with the blow heater then the radiator keeps it really toasty in setting 1 of 3 and the thermostat at about 25%

I’ve a similar shed from a company called Tuin- fixings will not help with the amount of movement a wooden building will experience, so if they’ve been added by the original owner, and can be removed safely, I’d say take them out. Ours gros by 12 to 1.5″ depending on season and has no gaps.
Tuin putting a layer of insulation between the tongue and groove wooden roof sheathing (the ceiling from the inside of the shed) and the shingles or felt on the top – sounded like celotex or kingspan in the description I read. I had a concrete pad to put mine on, so put in a floating floor with insulation.

In addition to what others have suggested for roof and floor – I’d get some decent heavy curtains for the windows – even if you have to open them when working (do you need them all open?) then they will help you get it warm on a timer before you go out there.

What roof covering do you have currently? It should be reasonably straightforward to remove that, put celotex down and then a new roof covering over the top.

That’s how ours is done, roof boarded, celotex then roofing shingles fixed through the celotex into boards. Hardest part was finding the right length clout nails iirc

We have a dunster house severn cabin, with insulation on floor and ceiling. Floor is maybe 25mm and is laid below the floor, with a small gap between floor. Roof is insulated above the internal roof and below the shingles. The walls are also 45mm wide.

At the moment it is REALLY cold down there even with that insulation with a 2kW (supposedly) heater.

Expanding foam has been used between floor and wall and clear silicon between wall and roof.

Yep – what eybygomm did up there ^ was what I was told works. You can use wider barge boards to finish off.

I picked up a £10 fan heater in Lidl a while back to give our boxroom/office a little bit of extra heat during the day when needed instead of firing up the whole central heating system. It seemed to work pretty well in the shed when doing a bit of maintenance in the evenings.

there are truss rods (or whatever they are called) at various points through the timbers but it seems impossible to fully close the gaps up at the top where walls join the roof

I think you may mean the storm braces. Don’t do what someone up there suggested and get rid. They are not for keeping the walls from expanding etc they are to stop high winds lifting the roof and first few lengths.

how are you heating it and how long are you heating it for? if you’re just nipping in there for an hour at a time (to fettle a bike or similar) – I think insulation wont make much of a difference to heating costs, and if you’re not heating it at all it’ll make no difference.

As per Scandal’s comment above, my “storm braces” had to be cut through back in the late spring because they were actually holding the roof off the rest of the structure. I chopped through and the roof dropped back onto the walls. The braces were too long by 10-15mm, now in the winter they would be around about the right length.

I do hold my breath whenever there’s a storm however. (no sign of the roof coming off so far though, not even a hint)

I think you may mean the storm braces. Don’t do what someone up there suggested and get rid.

Very, very good point – I’d forgotten about those, since mine went in a very sheltered spot. Thank you for picking that up, Scandal! That said, their presence shouldn’t distort the building. This one has springs that allow it to move with the timber, although they also recommend a slotted piece of timber, which I imaging is a heck of a lot cheaper.

This was a pretty good starting point for me, OP: https://www.tuin.co.uk/blog/tuin-tuindeco-log-cabins-instruction-manual/

Following this.

Don’t just put insulation between the rafters and cover over as you will get condensation problems in the roof unless you have a vented gap between the insulation and the roof deck. You would be best to put the insulation on the outside between the roof deck and the shingles/tiles/rubber (whatever covering you have). Ideally you should put a vapour barrier in too. Have a google of warm roofs and cold roofs – warm is the better of the 2 but makes the building higher so make sure you don’t breach any permitted development rules. Ali Dymock on YouTube has a good video explaining the 2 types of roofs.

As mentioned above, focus on roof and floor first. Then the walls and windows.

Thanks for all the input, i’ve found a couple of issues with the shed that are creating drafta that I need to sort first.

Seems like the wood lengths may be sitting on top of the door and windows frames hence not settling. Also got a gap either edge under door I can sprt with a seal.

The decking butts against the outside so the floor and it’s makind the wood damp, easy fix I hope to lift the board, trim and refit, along with some guttering.

Storm braces on this are on and set with a gap to allow for expansion, the guide for this cabin was to tighten them down each season to resettle any loose timbers and then wind back off a few cm to allow for expansion again.

Roof is unknown thickness timbers with shingle and a fake peak thing, no insulation so prime to do if can sort drafts out.

I am in this up 8 hours a day 3-5 days a week. Heater is a small blow heater for quick boost then oil filled but guess I am just pissing heat out everywhere.

Will have to check height to see if can put insulation above. If went inside of roof there is a huge overhang where the storage cupboard is at the back so venting is easy to sort. Even the current gaps should vent it enough.

I dropped out the door assembly today to suss out leaks around it and if it was rotting under the frame or not.

When I say dropped I literally mean dropped, was left holding the frame as it fell away from me and the glass exploded on my son’s picnic table.

2 new glazing units, a new picnic table, and possibly a stitch or 3 required.

If low occupancy then condensation will be less of an issue.

Condensation is more of an issue in air tight houses where people are having hot showers, cooking, drying clothes on radiators etc.

For reference to those following I have given up for now – the integration of door and window frames is non-existent. I had expected the slats would interface with the door frame, then the door assembly fit into the frame.

Instead the trim piece inside and outside the shed forms a U shaped channel which the walls slot into. The slats are not all the same length and the assembly is a very loose fit, letting air blow through all around the edges. The slack means it all moves anyhow.

In my view it wants trimming back and a proper frame put in (U interface probably fine but far stronger and tighter), then the door assembly refitted solidly within it.

There is some damp in the subframe from being butted up against the decking, so I’m going to sort that and see how well it dries out before risking hours wasted time sorting it only for it to rot through anyhow. May well end up taking out some of the base and replacing, that would be a good time to put in a proper door frame.

A lot of this comes down to the original installers as much as how the kit fits together. They dealt with the slackness by screwing the frame to the slats, meaning they couldn’t expand and contract as they should and then ended up warping in strange ways. The previous owners of the house didn’t maintain the shed over seasons and years either, which also hasn’t helped.

Boombang – very similar to the construction of my cabin too. I once caused a flood by hosing down the outside to clean it, only to discover the water got in via the U-shaped channel.

Mine works properly because the window frames are hung at the top with a chunky bolt through the frame and into the log slat across the top (the one that is effectively the lintel). As the shed expands and contracts the window maintains pressure down through the walls either side and keeps it all tight. As I describe above, it’s not water tight, but there’s no way I feel a breeze through inside the shed. I have pondered trying to fill the gap with some sort of foam draft excluder but given how cold it’s been in recent days and how warm the shed has stayed there’s really no need from my point of view. (The frost/snow on the roof has remained completely in place, which given the roof overhang I would have expected to melted if a significant heat-loss from around the window had been happening.)

The door frame is almost independent to the rest of the shed – the slats slot into the u-frame around the door, but the downward pressure from the roof is carried through an independent lintel – the top of the door frame is effectively separate and there’s an expansion joint between it and the rest of the shed. (I had to cut a chunk out of the roof joist back in the summer as it was resting on the top of the frame and not floating free – this was at the same time as I cut the storm braces).

I guess it helps that I put the shed together from a kit that was delivered so I understand how it all works as a unit. I’d suggest that you take a look and see if your windows/doors are supposed function as I describe – it might actually be a fairly simple fix to get it all working properly.

My shed is getting on for 9 years old now. It’s absolutely solid, warm and a nice place to be.