Exposed RSJ?

[tom.harrigan]

Hi

I have 3m of RSJ supporting a gully over a bedroom. As it's not supporting a wall, could I leave it exposed, or must I box it in?

Regards

T

[Rick]

and whatever they hold up comes down, long before the wood/brick would come dwon from the effect of fire..

Rick

[meow2222]

You can leave it as it is if you wish. If its just been installed you need to meet BR, which is done either by boxing in or painting with intumescent paint

[Hugo Nebula]

On 21 May 2007 08:41:04 -0700, a particular chimpanzee, Rick randomly hit the keyboard and produced:

An RSJ or a UB seems a bit overkill to support a gully (unless you mean a valley). If the beam in question only supports part of the roof and not any floor over, and does not provide restraint to a wall which needs fire resistance due to being close to a boundary, then it does not require fire resistance.

If the fire is intense enough to weaken the steel supporting a roof, anyone in the room below is already toast.

[Weatherlawyer]

Not necessarily. In a large conflagration the wind storm heats the roofs of houses nearby -on the lea side of the current.

Boxing in an RSJ:

Measure the aperture that will hold the 2 x 2s. Cut the 2 x 2s at that length with a slight bevel top and bottom so they slide in. Hammer one such every 4 or 6 hundred millimetres plus an extra at the end of the run each side of the beam. Remember the actual shape of the section is bevelled.

(IIRC cutting the 2 x 2 an eighth smaller will allow you to put the (2 x 1) baton flush.)

Screw or nail a baton top and bottom each side the beam to the 2 x 2s. Clad top, bottom (first) and sides with 3/4 ply.

Job done, if needed.

I am not saying you need to, just how to do it. If you want more protection just keep adding layers of ply. (The end result of putting

2 x 2s in the RSJ is an overall increase in its load bearing ability if that helps.)