Garage Office Insulation

[Laurence737]

Hi Everyone,

 

I’ve finally got around to converting the room above our double car port into a functional office.

 

I just had a quick question about insulation, the floor of the office is timber and below are the joists that form the ceiling of the car port (see photos)

 

I just wondered what the best way to insulate this space and keep it dry?

 

I was thinking of PIR between the joists, a waterproof membrane below and then cover the bottom with MDF boards? And what is the best way to insulate the sections with the braces?

 

Thanks

[Cpd]

I recently insulated a room in the roof of my shed and filled between the joist with rockwool batts and then put 50mm of kingspan below the joists, foamed and glued joints and then covered the whole lot with osb. Not sure if this is best practice but it works great. 

[tonyshouse]

Best NOT to have a vapour barrier or impervious layer on the cold side of the insulation, MDF is prone to swell and change dimensions irreversibly if it gets damp 

[Laurence737]

14 hours ago, tonyshouse said:

Best NOT to have a vapour barrier or impervious layer on the cold side of the insulation, MDF is prone to swell and change dimensions irreversibly if it gets damp 

Thanks for that, what would you recommend as the best way to insulate it and keep it all dry?

[tonyshouse]

Vapour barrier on the warm side of the insulation 

[JohnB]

Hi there, So Standard PIR insulation like Celotex and Kingspan is the most popular option for this job. The best way is to insulate, I would pack the ceiling with Celotex and I would use foil tape to tape joints, make sure no gaps are left. Vapour controls layers along with the same tapes are recommended to the warm side of the insulation as an added layer to combat condensation build-up.