Insulation recommendations for brick built outbuilding pleas

[Stevet284]

Hi,

I'm going to convert a brick built workshop into an office.
Since it is an outbuilding I do not think i need building regs, but i will still try and do a job good enough to meet them if required

Currently the room has a concrete slab floor single brick walls.
the roof is pitched, but there is already a ceiling which i have fitted 120mm Celotex between the joists.

I am planning to build a raised wooden floor using 100mm *50mm joists and with 18mm tongue and groove chipboard on top.
Anymore than that and I would need to raise the door.

I will install a DPM, I was planning on using 100mm Celotex for the floor and also the walls, but now I have read that i need an air gap.

Please can someone advise what size air gaps are required for the floor and walls and recommend what size celotex/Kingspan I should use.

Many Thanks in Advance
Steve

 

[noseall]

You don't necessarily need an air gap it depends upon what system you use.

Fully filling between 100mm studs with another 25mm across the studs will give you decent thermal resistance values.

You will be better off using foil coated insulation and be pretty accurate with cutting and sealing any gaps. Use foil tape and silicon mastic to seal gaps.

Using foil back plasterboards will add to any protection you already have.