Question about RSJs

[dodgem101]

Hi,

I'm new here... as you can tell from my post count! Though i've read a lot of useful info on this site

I'm planning a kitchen extension at the moment and will be knocking through the back wall of my house. It's an old terraced house - i believe from the late 1800s, and the external walls are solid and one brick length thick (i can't remember the term, but it's where every other brick is turned 90 degrees to tie the wall together).

Obviously i will require an RSJ - the opening will be about 3m and i have about 1m spare each side to support it. My first question is, how is the load from my wall (approx 200mm wide) supported by the RSJ which i guess won't be much more than 100mm wide? Or should i be speccing 2 RSJs for the job? I have spoken to a SE, but only in as much as i am sending him my plans so he can quote for the calcs.

Second question: I keep seeing people mentioning Strongboys or needles. Since my ceiling joists run perpendicular to the wall, are these needed? I would have thought i can spread the load on the ceiling with scaffold planks and acro those close to the wall, so the joists are supporting the wall above? In fact, since i am removing the plaster and lathe ceiling and putting new plasterboard up, i could place the planks directly under the joists without old crumbly plaster inbetween.

I am in 2 minds as to whether to tackle it myself at the moment... depends how much i get quoted for the job!

Thanks in advance for any answers and advice!

Simon

 

[Static]

I have spoken to a SE, but only in as much as i am sending him my plans so he can quote for the calcs.

Your SE will specify either a larger width beam or two beams or a steel plate on the top to support the load..

Strongboys are used to support the brickwork above the opening being made.. if you are taking out the whole lot to roof level then using scaff board and a few acros should be fine.. but if there is wall above you will need to support it while you work below..

 

[dodgem101]

Cheers Static.

I've had a builder round who quoted a pretty reasonable £1000 to fit the RSJ and take away the old material. That was leaving me to box it in and make good.

While he was looking at the job though, he suggested i might be able to use two box lintels instead of the RSJ since the span is less than 3m. The advantage being that i wouldn't need calcs from a SE for building control, just for BC to check the foundations were ok to support the load.

How does that sound? The lintels or RSJ are to support the first floor external wall and the roof above. He has done plenty of this sort of work before, but i don't know whether it would be considered a little cowboyish to use lintels instead of a RSJ?

 

[amwc]

Hi two box lintels are fine as long as they are adequate to take the load. Unfortunately BC don't seem too bothered about this. You may be able to get the linel supplier to size them for you. I'd go with the SE still, the amount he would charge is a fraction of the builders charge and you would have peace of mind.

 

[Static]

Standard lintels dont tend to work over 2.5m openings unless you have pretty lightly loaded wall..