Loft room above detached garage?

[Giblets46]

Hi there,
Just moved into a new house, it's in a conservation area (which affects what I can do) but it has a detached double garage which I am keen to convert the loft area into an office.t shining perhaps as a 'storage room's rather than a room.
It's double skinned and there is a nice steel joist running through, so it should be able to support a room. But not sure there is enough height to support building regs, ESP with the insulation Needed. Joists and rafters are 130mm.
Also what would be the best option for dealing with the hatch?! All thoughts and ideas appreciated. Images below

 

[chappers]

looks like someone has already put that steel to make the floor structuraly sound. Those joist should be able to span around 2.5 m.
Are you really worried about it being up to regs, you have enough depth in the rafters for 75mm insulation between and then 50mm under which would get you close to regs and if you put that in building control wouldn't know anyway.
Looks like you have close to 2.5m at the apex anyway, only you can decide if you have enough space with specific headroom, when you take the pitch of the roof into consideration.
Won't you be keeping the hatch as your access point. If you want to convert to regs as a habitable room you have further things to consider not just the levels of insulation.

 

[Giblets46]

Thanks for the advice, guessing the major remaining issue would be the 30mins fire regs.
My understanding is that I would need to fit a fire door to the office and to the entrance to the detached garage (and check the window is fit to use). Fire alarms and I'm guessing I would need to address the floor itself and use suitable insulation (would I need to check the ceiling of the garage too?).

 

[Giblets46]

OK,
so it would appear that I may have been wasting your time, apologies for doing so! I just spoke to the local building regs office (South Northamptonshire), who advised me that as long as the garage is detached, under 30sqM, and contains no sleeping accomodation, then it falls outside the building regs...
Obviously in terms of safety and heat efficiency I will try and keep the regs in mind (as they are intended for safety in mind).

 

[Giblets46]

And another....back to square one! Asked for written confirmation, and advised this time i do require regs!

 

[Giblets46]

Righty, finally getting round to starting this project (utility room and new kitchen took priority!).
Following the comments above, looking at avoiding the regs route, but wondering if 75mm celotex then wallboard will be sufficient for insulation (I know more is better, but it's the law of diminishing returns ), to keep the room relatively warm (designed as an office not a bedroom).
I've worked out around head height the width is only around 1m or, so adding much more over the rafters will really impact that.

Edit: my rough calculations make the u-value of around 0.27. which was actually near the regs required in 1990-2002, which was when the house was built. With the re-inforced floor beams, the height of the window etc, seems the roof space may have been built with some sort of conversion in mind.

 

[Giblets46]

So I'm done, lots of fun along the way, never done plastering before so no complaints, back handed compliment from the other half saying it's better than she thought I'd do!