walls first.
Make sure you have a secondary (fire escape) exit ... Building Regs will
want one.

Think well about insulation, heat loss will be significant, and just
plonking insulation in, is not good enough - need to consider water vapour,
or you could end up with interstitial condensation.
also importantly think about heat gain if a dark roof - or room will be
baking in Summer.

I would use a foil faced Urethane foam board.


"Bypass" wrote in message
...
TomC wrote:
Hello,

I want to divide my large roof space (triangular cross-section 4m high
at highest point) into 2 bedrooms by timber partition walls.
Currently the roof insulation is exposed and I can see the roof joints
(to which of course I will be fixing the head plate of my future
partitions).

Should I build the partition walls before "closing the roof" (will be
using timber cladding for the roof) or should I do the roof first
meaning that the cladding will between the head-plate and the joist ?

I'm going to need to pass electricity cables through the studs of the
partition wall so it seems to me more practical to build the walls
before doing the roof cladding. The power cables are in position
already behind the roof joists and thus currently easliy accessed.

Ideally I want to do the cladding now so that the roof space is usable
in the short term but say in 2 years divide the space into 2 rooms.
Any advice on the pros and cons of the two approaches would be
gratefully received.



Tom

You would normally do the walls first and then clad everything afterwards.

You do realise you need Building Regulations approval for a roof
conversion, don't you? (check out your Local Authority's website.) Should
you decide to proceed with an unauthorised conversion (which isn't wise),
then for safety's sake, at least take into account how anyone trapped in
your roof space will manage to escape in the event of a fire.