Universal beams - Issues for my untrained mind

[pilsbury]

Have had the foundation trenches passed for my side kitchen extension by building control and have poured my concrete thus now considering myself a professional builder! All good. I intend to reuse the bricks from my exterior kitchen wall to build below DPC so they match the rest of the house (75mm imperials) as I am finding it very hard to find something similar. Above is to be rendered block. Anyhow, this means the removal of the kitchen wall and insertion of steel beams.

The opening span is 357cm so with a 10cm bearing on either side would require a 377cm beam/s. All they are to hold up is the gable end of the current single story kitchen. The outer skin obviously goes full height, but the inner skin only goes up halfway (pic). The new warm flat roof will cover the outer beam. My BCO officer suggested 2 x 6x4" beams bolted together to support both inner and outer skin of my 9" solid wall, then suggested 7" beams might be better. He agreed SE calcs are unnecessary for this support. Cost for beams is £200 - not bad.

Having bashed an exploratory hole in the old kitchen ceiling, I have come to the conclusion that to maintain the 9' roof height between old kitchen and the soon to be started new part of the kitchen, the steel beams need to sit level with the top of the wall plate on the old kitchen roof to avoid being on display in the ceiling. This presents a problem as even if I were to go for the smaller 6" beams, the top would hit the laths of the old kitchen ceiling.

Enough rambilng from me - Questions:

1. Will 2x 6x4" beams bolted together be sufficient?
2. How can I fit them in so that they sit level with the top of the original wall plate?

Help appreciated from a learn as you go have a go hero.

 

[noseall]

Some of the top portion of the beam can be cut off or chamfered to coincide with the roof slope. The amount you can remove will be quite specific.

You BCO is very affable in designing and being responsible for your steel beam design. What size pad-stones and bolting /spacing arrangement has he come up with? Ask him to design the chamfer too.

 

[pilsbury]

Thanks for the info on being able to chamfer the beams. The other fallback I have is to fit the unchamfered beams as high as they can go leaving approx 3" below the ceiling, then just lower that by battoning the current joists. Just adjust my extension ceiling accordingly. Keen to exhaust the no loss of height options first.

The BCO was very pleasant.... having never dealt with one before, I had it in my head he would be a little Hitler. As for his SE qualifications, I can't comment, however he did mention something along the lines of the span being less than 4m and in this application SE calcs were not required.

He suggested 3 courses of engineering bricks below the beam would be adequate or better would be a similar sized padstone. As for bolting or spacing arrangements, I've left that to the beam company.

Now this is where I'll probably get flamed, but it's not as though I'm opening up the entire span of a 2 storey property..... The beams will support nothing but the pyramid of bricks above. 2 6x4" beams seems overkill to me anyway.

 

[noseall]

Now this is where I'll probably get flamed, but it's not as though I'm opening up the entire span of a 2 storey property..... The beams will support nothing but the pyramid of bricks above. 2 6x4" beams seems overkill to me anyway.

Gables are more susceptible to down force loading than a full width panel of brickwork.

 

[pilsbury]

I can see that - full panels of brick have the "sides" to help hold them up, whereas my gable's sides disappear the higher you go..... What's the worst that could happen?!!!

 

[tony1851]

I can see that - full panels of brick have the "sides" to help hold them up, whereas my gable's sides disappear the higher you go..... What's the worst that could happen?!!!

The "worst" that could happen is that you might get excessive deflection of the beam(s) which could crack the plaster finish.
But a 152 x 89 is probably be OK on a 3.6m span; I think your 100 bearings are possibly a little short.
The inspector should not really be giving structural advice - his job is to inspect only.

 

[catlad]

The "worst" that could happen is that you might get excessive deflection of the beam(s) which could crack the plaster finish.
But a 152 x 89 is probably be OK on a 3.6m span; I think your 100 bearings are possibly a little short.
The inspector should not really be giving structural advice - his job is to inspect only.

The "worst" that could happen is that you might get excessive deflection of the beam(s) which could crack the plaster finish.
But a 152 x 89 is probably be OK on a 3.6m span; I think your 100 bearings are possibly a little short.
The inspector should not really be giving structural advice - his job is to inspect only.

 

[catlad]

I don't think he was giving advice really saying 9" beams would be ok !

 

[pilsbury]

I don't think he was giving advice really saying 9" beams would be ok !

6" ...... but you are correct in what you say. It was a chat when I was telling him what I was intending. He offered his thoughts on what he'd accept which was good enough for me.

 

[noseall]

He offered his thoughts on what he'd accept which was good enough for me.

 

[pilsbury]

Anyone got any thoughts on the 2 bolted 6x4" beams? Not expecting SE calcs, but does it seem reasonable? Or is it obviously under specced?

The comment on the 100mm bearing - can only really do this on a solid wall. Has to sit on 1 brick width. The padstone or engineering brick will be sizeable, probably block sized.