Converting part of garage

[ibruceuk]

Hi



I currently have a fairly large garage and am looking to make part of it slightly more comfortable as a sort of home office (basically my wife and I are teachers and need to have some quiet time for marking/planning etc and we also want to keep school work out of the house). So this will involve construction of a partition wall and then upgrading the existing within the new “room”.



At the moment the garage is constructed as follows from outside to inside…



Floor – Concrete (unsure of depth and doubt the existence of a DPM although the garage is bone dry

Walls – Prefab concrete section -> 50mm Celotex style board -> Plasterboard -> paint

Flat Roof (well slight pitch…) – Torched on felt -> OSB resting on rafters (there is 50mm Celotex cut to fit between rafters and this is tight up against the roof.



My initial thoughts are



Floor – 75mm EPS -> OSB -> Carpet tiles

External Walls – Add 25mm battens and 25mm of EPS then standard plastboard, plaster and paint add double glazed window (with trickle vents and escape provision) to one wall.

NEW Partition wall – 3x2 frame with 75mm EPS and fireline plasterboard garage side and normal internally

Roof – add 75mm EPS to fill remaining space between rafters then plasterboard (vapour barrier stuff) then plaster and paint…



Can anyone see any issues here?



Would I need to have breathing space anywhere in the ceiling layers? (the garage is currently heated to a very low level and there is no condensation that I can see)

Do I need to add vapour barriers anywhere or use vapour barrier plasterboard as an alternative?



Thanks in advance…

 

[ibruceuk]

No opinions???

 

[freddiemercurystwin]

/sigh

There are hundreds of threads already advising on this very subject. Have a search.

 

[ibruceuk]

Thanks for the response fmt, I realise many people have posted and I did search but I was looking more for an opinion based answer as the garage is already semi-insulated.

Would it be worth me adding the 25mm EPS and if I did would I need a vapour barrier (I don't think there is an existing one with the celotex)?

The roof certainly doesn't have a vapour barrier so I'm guessing I would need one on the inside of the extra insulation and before the plasterboard, would I need to drop the existing insulation somewhat as it is tight up against the OSB?

Thanks for any advice...