Loft conversion, a few questions...

[SPOODZ]

Just moved into an end terrace, had a look in my loft, and apart from being a mess (seems to be full of soot and hay!) there is space for a single room loft conversion.

My questions all revolve around joists. Currently there is an existing ceiling (lat and plaster on 4x2 battons) and a false ceiling 18" below(plasterboard on 3x2). Am I ok to rip out both ceilings? or will the original battons have anything to do with supporting the roof trusses?

Next, How long can a joist be? I assume I need 6x2. In one direction the room is 14ft, in the other it is 12ft, but one of the walls is studded partition. is 14ft too long? will the joists bow?

I intend to run the joists along the 14ft wall, attaching them just below the where the false ceiling is, with face fixing joist hangers (see http://www.parkesgroup.co.uk/catalogue/default.asp?cat=5&itm=41&catmain=1&catmenu=5&itmlist=)

Any thoughts as to whether this will be up to the building regs?

Sorry about the lengthy message !

 

[SPOODZ]

Just re-read that, to clarify one point, the 14ft dimension of the room has 2 solid brick walls, its the direction that has one solid and one studded wall.

 

[masona]

Any thoughts as to whether this will be up to the building regs?

The joists size you're quoting won't be bigger enough, you will need building permission approval, pop down to your local building control for a free advice and they will help you what you will need to do.

 

[chappers]

The ceiling ties attached to your roof rafters do have a job of helping to stop the rafters splaying out but it is possible to remove them and provide lateral bracing from a purlin wall, which will almost certainly be necessary to help support your rafters.
For a 14ft span, you will be looking at 8x2 timbers minimum but maybe even thicker it depends on what deflection can be restrained by the hangers you intend to use.
As to whether it conforms to building regs you will have to prove this to them by way of a structural engineers calculations.
I could pretty much specify you with all the specs for a loft conversion, that would meet building regs but unfortunately they would require this to be backed up by structural engineers calcs. and these depend a lot on the structure of the rest of your house.
Do yourself a favour and if you are seriously thinking of converting your loft then get an architect and structural engineer involved from the start.

 

[SPOODZ]

Are they expensive? I have a friend who converted his loft (with the assistance of his father - a builder) for 3k, thats was for materials and getting building control to sign it off.

 

[chappers]

I wouldn't expect much change from £1000 for architect/structural engineer and your BC fees.
Also £3k seems very low i would expect to put £6k+ into a loft in materials alone.