Hello all,

I'm working from home a lot and we need another office, so I'm planning to create a 2.2x2.5m office and inside part of a large detached wooden shed. The shed is decent and dry so I'm sort of creating a basic timber frame warm box.

My plan is to go low embodied carbon, cost effective and easy to assemble in couple of weekends.

Floor, 1000gauge dpm, 50mm phenolic [already salvaged from a skip], 18mm osb, second hand flooring tbd.

Walls/ceiling, old feather edge fencing planks to protect from damage, breather membrane, 100mm pavaflex, tapered edge plasterboard, filler + Paint.

Door (2 internal doors we already have one opening in, one opening out).

I was going to insulate it more, but given the tiny space I calculate even at dT=20 it will need <300W (i.e. a person, computer and monitor) so more insulation seemed pointless.

planning on fully breathable construction so no vapour control membranes

Am I missing any thing here?
I think we avoid regs as it's a shed?
(will run on an extension lead plugged into an outside weatherproof socket)

Is a single room heat recovery unit overkill?

thanks

edited for typo

I was going to say pretty much the same as PiH. It sounds like ventilation/cooling in summer will be more of an issue than keeping warm in winter, though you'll probably want something to keep it above freezing in winter and make it comfortable when you first sit down. A window sounds like a very good idea too.

If it's doable I'd consider a double roof structure - a flying roof with an open air gap under it and then the 'real' roof. The idea is to keep the sun off the roof (and maybe the walls to some extent) so the insulation isn't trying to deal with too large a temperature difference. Maybe the flying roof could be solar panels?

Great stuff thanks both.

Was planning on full air gap on walls and ceiling for over heating reasons.

Window a good idea, have an old one the supplier made wrong hanging about.

For the floor I'm aiming to minimise the height build up but don't want it to creak. Should I plug the OSB down hard onto the existing concrete floor with concrete screews? This seems sensible but means they will be scared going through the DPM ( albeit into a visibility dry and dusty for)

Posted By: jms452For the floor I'm aiming to minimise the height build up but don't want it to creak. Should I plug the OSB down hard onto the existing concrete floor with concrete screews? This seems sensible but means they will be scared going through the DPM ( albeit into a visibility dry and dusty for)

For the floor, assuming the concrete is flat perhaps consider
1000gauge dpm, 50mm phenolic [already salvaged from a skip],
Then forget the 18mm OSB and go for click fit flooring as a loose laid floor between the walls. I would go for the type suitable for bathrooms so there will be no issue with damp. By the time you have not brought the OSB and sourced the 2nd hand flooring there may not be much difference in cost - and it won't creak.

18 mm floor will move unless supported everywhere. I put 22 mm T&G Caber on top of the floor that came with my shed and that's a lot more rigid, though still some movement.