Office inside of sectional concrete garage

[Craig24]

Hi,

I am looking to convert a small section of my concrete garage into an office space. I know this isn't ideal but I need the rest of the garage and don't want to knock the whole thing down to start again with a timber structure.

My thinking is to build a freestanding stud wall structure inside, it will butt up to 3 of the concrete walls, not sure if they should be attached or freestanding?

I'm not 100% sure then on how to insulate and if I'll need breathable membrane and vapor barrier?

Also it currently has a concrete floor, I'm thinking of building a insulated suspended floor in this area?

Any advice but appreciated as I am a novice DIYER and need to do this DIY as I'm on a budget

 

[morqthana]

Normally you'd want an internally insulated layer like that to have a vapour barrier on the warm side of the insulation to stop warm moist air getting to the cold space and condensing. That's probably less of a concern here, but PUR insulation with a VCL isn't a lot more expensive, so you might as well. Breather membranes are more about allowing any moisture to escape but keeping water out. Presumably your garage is pretty leaky from a ventilation POV, but keeps the rain out? Can't see where or why you'd use one here.

Fixing the structure to the walls would be good, but you might find it difficult to drill holes in them, and they aren't very thick. But if you think about it, stud walls are usually not attached. You should be able to get a sole plate firmly fixed to the slab, and a head plate fixed to the roof trusses (I assume that's what you have?)

Do you have the height for a suspended floor? You could just lay insulation boards on the slab.

 

[freddiemercurystwin]

Does the roof leak?

 

[jj4091]

Have you thought of buying a small ready made shed that you could put in your garage.

 

[freddiemercurystwin]

Why? That would just come with a load of useless external cladding and roofing you can't install. I quite like the OP's approach.

 

[Craig24]

Thanks! No the roof doesn’t leak.

What sort of thickness and material of insulation for both floor and walls should I be looking at?

If I put insulation board on the slab, could I then just put flooring sheets over that I take it? Cheers

 

[morqthana]

Yup

Got the space for 100mm? PUR or PIR. https://insulationmanufacturers.org.uk/inside-insulation/types-of-insulation-2/

You'll need an insulated top to your box as well, or to insulate the roof of the garage.

I'd suggest an ASHP to heat it in winter and cool it in summer.

 

[Craig24]

Thank you. Just had a quick measure up and for space and cost, I’m considering 2x3 cls for stud work and then 50mm pir for walls and 100mm for floor and ceiling.

Would 50mm for walls be a bad choice for walls? Would it make a huge difference over 100mm for a small office space?

 

[morqthana]

50 will give useful performance IMO.

 

[Craig24]

Thanks again.

Any advice on best way to construct the roof of this box in a box.

Cold roof or warm roof? I think I'd struggle to do a warm roof as I won't have access to the top of this box when constructed due to the garage roof.

 

[morqthana]

It's neither, really, isn't it?

Just an insulated lid on the box which looks a lot like the walls, no? With some indeterminate gap between there and the roof panels?

 

[Craig24]

Ok, so just insulated the roof same as walls, vapour barrier sheet over insulation, then plaster board should be ok?

Thanks again, really appreciate the help.

 

[morqthana]

Should be, if the garage roof doesn't leak.