Building workshop (double-leaf wall or single-leaf with internal insulation)?

isaac azimov

Hi,

I'm building a (stand-alone) workshop on an exposed site.

It's just 6m wide X 10m long (with possibly another 6m X 10m 'extension' to be added at a later date).
It will be 4.5m high to eaves.
It will be a steel portal frame (heavy-duty, galvanised IPE / UB structure) from a local supplier.
It will have insulated roof panels (100mm-thick).
It will also have a 4m X 4m insulated 'sectional' workshop door (made from 100mm-thick insulated panels).
I will build block walls between the stanchions (steel uprights).

Given that this workshop needs to be as insulated and warm as possible (and as free from condensation as possible), the question is:

Is it worth building a double-leaf wall (like a domestic house) and insulating the cavity in between (with insulating board, etc)?

Or, is that a waste, given that almost the entirety of one wall will be a big (albeit insulated) door? Would it be, in reality, as good just to go for a single-leaf block wall and fit very thick internal insulated slabs?

(Is it hard to control condensation with a single-leaf wall with internal insulation only?)

Don't see external wall insulation as an option, as outer wall will be clad in stone.

Disadvantage of internal insulation is that there won't be as rigid/strong an internal wall surface to drill / fix things too / etc?

Disadvantage of double-leaf wall is more cost re: wider foundations and more block-laying, etc.

Any thoughts or advice?

selfbuild17

Blockwork is porous and if your site is exposed it would be foolish not to build in a cavity.

Single leaf blockwork with internal insulation could result in dampness and mould growth behind the insulated slab.

If you want to minimise foundation width, go for a 50mm cavity and then internally insulate afterwards if you wish. If it was me, I would incorporate a 100mm cavity and pump insulation afterwards. That way you are left with solid internal walls which would be a plus for a workshop for fitting shelving, benches, etc.

The foundation size isn’t that much different for a 100-100-100 wall vs a 215 block on flat wall. The material cost is about the same

isaac azimov

Thanks for the reply.

The single-leaf wall would have left the build very simple, but what you're saying makes sense (about the potential for dampness with a single-leaf wall and internal insulation and nothing else).

rayjdav

As it is portal frame, why not just extend the 100mm RWP down side of building on cladding rails and build a wall 2m high where required between stanchions for grounds. Why you using stone cladding on a shed, it is a waste of money imo??

Lumen

rayjdav wrote: »

Why you using stone cladding on a shed, it is a waste of money imo??

Presumably a planning requirement to match the finish of the main house.

rayjdav

Lumen wrote: »

Presumably a planning requirement to match the finish of the main house.

IF that is the reason, keep it on the front elevation only. Total waste otherwise.. Its a shed.

Lumen

rayjdav wrote: »

IF that is the reason, keep it on the front elevation only. Total waste otherwise.. Its a shed.

Each to their own. Some people value aesthetics enough to spend money making things look nice.