Warm or cold roof for garage?

[Screech20]

Hey guys.

I'm currently planning on building my garage/workshop.

It's going to be 30m2, mostly timber frame, which will be insulated. Ill be spending a lot of time out there.

I'm now thinking what to do about the roof, and was thinking of warm flat roof but I think it would cost more, as I was thinking an osb deck, 50mm insulation, another osb deck (don't like the idea of just covering insulation, and being a bit soft under foot!) then covering.

Would I just be better of doing a basic flat roof then just fill the joists?

At the end of the day it's just a garage, I don't want a ceiling and would be nice to use the joists voids for storage.

 

[noseall]

Depends what you are prepared to put up with and how you are going to use the garage. In particular, how you ventilate the garage.

For instance, on a cold Winters day, all the doors and windows are tight shut, your portable heater is on and all that trapped moist air is gonna condense up in the joist voids and cause mould and damp in that area.
The stuff you store up there risks getting mouldy and damp also.

Leaving the ceiling open will help but it won't alleviate the condensation risk altogether.

Don't forget that a certain amount of cold will bridge through the joists on very cold days.

Why are you bothered about a spongy roof? What do you intend doing on the roof?

 

[Screech20]

It's going to be used to build and store classic Minis. So I want it as dry and damp free as possible.

So from that, you say warm roof would be the best way to go? Would 50mm be sufficient?

It will have double glazed windows and door, and a foam filled roller shutter. One wall will be full height single skin brick, not sure what I'm going to do with that yet.

I suppose I was a bit worried about damaging it when needing to get up there, not going to have parties up there.

I think it's going to be an EDPM roof, so might need something on top of the insulation?

Cheers