RSJ above garage opening

[JCB520]

Hi,

I am in the process of designing and building a 2 story extension on the side of my 3 bedroom detached house.
The extension wil be 4m wide x 7.5m long at ground floor (for a garage) and 4m x 6m at first floor level. The 1.5m extending bit on on the ground floor will be stepped in to 2.5m wide and have a flat roof. This will become a balcony for the new master bedroom on 1st floor.
The garage door opening will be 2.2m wide.
My question is this.

I will need 2 RSJ's to span the gap in the garage door opening and 2 where the rear of the garage steps in to support the external wall above. In effect it will be like having a garage door opening in the front and back of the ground floor room. 2 RSJs are needed. 1 for the inner and 1 for the outer leafs of the cavity wall.

Has anybody carried out similair work and what size RSJ did you use.
I am trying to cost up the job as i'm planning on doing most of the work myself.
I would also like the info for when building control ask for details on what I'm using to support the walls above.

Thanks
Dave

 

[hotrod]

Why do you want to use RSJs? Why not just use an appropriate IG or Catnic lintel for a given SWL/UDL?

As as example of price an IG L1/S 100 @2550mm (for your garage door opening) lists @ £190 but you should get a sizeable discount from your friendly local builders merchant.

You need to check the loadings before you decide on the type of lintel or the size of your RSJs.

 

[Shytalkz]

I think you missed that the OP was saying the first floor wall does not run over the ground floor wall. With floor, wall, roof load on the beam at first floor level, a standard IG or Crapnic is not going to work on a 4m span; it would need either a heavy duty version, or steels and the latter is likely to be cheaper than HD lintels. And easier to get hold of, HDs are not usually held in stock at BMs.

Either way, OP needs them designing, but I would be surprised if a couple of 178x102UBs didn't work.

 

[noseall]

we did a job late '05 similar span and used 2 pieces 203mm x 102mm bolted at 1.5m ctr.

padstones were 100mm x 300mm x 2 courses.

 

[hotrod]

I think you missed that the OP was saying the first floor wall does not run over the ground floor wall.

I did Shy . Strange the OP hasn't posted, there's a lot of 1 post wonders on here

 

[JCB520]

Hmm don't know about being called a one post wonder
Just come off night shift and only managed to get back onto my PC
Anyway.

The beams only have to span a gap of 2.5m. At the front this will be above the garage door.
At the back, the side wall steps in from 4m wide to 2.5 m wide. This is due to our side boundary being at a angle. The point where it steps in to 2.5m is where the 1st floor wall will be, so this beam will only have to span from the 2.5m step in point to the original house wall.

I asked the question because the openings are pretty normal sizes for anyone who has built a two story extension with a garage underneath.
There is nothing special on the 1st floor and the roof will just be a plain pitched with a gable end.

I was after a idea what other people have used so I can run it passed building control. If I have to I will increase the size to overcompensate.

Anyway, any more help would be greatly appreciated.
Thanks
Dave

 

[noseall]

The beams only have to span a gap of 2.5m. At the front this will be above the garage door.

oh, i thought you were spanning around 4m ish.

my own extension had a similar scenario except it was only a 2250mm span.

for this we used a pair of 152mm x 89mm u beams bolted at 600mm centres.