Some advice about changing loft to cinema room please.

[Trojan]

Hi
I am hoping that I can get some advice on a couple of things that I am not sure about. I am about to get a new roof and thought it would be a good time to also put the loft to good use.
I am not talking about a full loft conversion but something like what Northern Monkey has done. I will not be putting in a staircase and will be using a retractable loft ladder. The roofer has said that he will put in 2 new roof purlins either side of the roof which are 9x3s to give me more space.
The roof will be covered in man made tiles which are very light and give the appearance of slate. The ceiling joists are not really strong enough to walk on so I will be putting in a new floor made up of 6 x2 joists.
Now here is what I was thinking of doing regarding the floor. From party wall to party wall is a span of 6 metres and what I was going to do was put 2 9x3 wooded beams from wall to wall just above the ceiling joists.
These would be placed near the eaves and I would then use joist hangers to put my 6x2s in between. I could even double up on the wooden beams which would make then 9x6 if you think that a 9x3 beam would not be enough for the span.
I would like to abide by building regs if possible but I am worried that they will insist on steel beams. I have no plans to sell as we are well settled here but I am concerned that if I do not follow building regs about the beams that it might affect our home insurance.
So my questions are do building reg always insist on steel beams as I would have thought the a 9X6 wooden beam would be strong enough.
I am also happy to call it a storage space if by some mishap that we have to sell butits just the house insurance thing that is the real worry.
Sorry about the long post but any advice would be gtrat.

Thanks

[MarkP80]

Hi Trojan,

Building regs do not require you to fit steel beams, just that the new floor is adequate to carry the load for a habitable room.

I would give the building inspector a ring and talk to him about it, you will find them helpful. Usually they can tell you from experience what will work and what will not. Even if you take the view that you are doing the floor mods now for possible later conversion to a regs-approved room, they will assist, and enable you to have a floor that could be signed off later if you wanted to.

The usual way is to fit new joists parallel to the old, spanning the wall plates. They are normally packed up, so they are slightly above the old ceiling. That way the old ceiling remains independant of the new floor.

As I say, I'd ask the inspector's advice/opinion.

Cheers,
MarkP