Ok, how will this work? (RSJ related)

Soldato
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Looks like the currently installed beam is too high in that case. I can't see how theyd do it.

In contrast If the sub floor it's supporting was too high (ie. Red beam too low) then you could prop timbers under the blue beam.

FYI I'm no expert!
 
Associate
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If a builder is doing this - I wouldn't let any more work commence until you and the builder clearly understand whats going on. You will likely have to box in the Blue beam unless your dropping your ceiling height.

A t section is usually used to join beams - i'd say the rear beam is set too high and its not been planned properly, if your paying for this get them to put it right.
 
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Is it possible that the builder is planning on fitting the blue beam at joist level? I.e. cutting through the joists and hanging them onto the blue beam, allowing the blue beam to sit at the same height as the red beam. Ths would also mean that the blue beam would get hidden in your ceiling, which is an added bonus.
 
Soldato
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Somewhere in the middle.
I'm not clued up enough to help you but please keep us updated on progress. My 1930s semi is identical and we are starting building work on an extension similar to yours in January.

We opted to leave internal walls in and just remove the large patio door for access. Didn't wanna spend more money on steels and we liked the idea of making our current kitchen into a utility room and having our dining room as a "snug".
 
Soldato
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It seems highly unlikely that cutting existing joists to bodge into a steel has been planned for.

You'd simply avoid such risky and complicated work and have the other steel at an appropriate level.

Bottom line is you either have a boxed in steel or a lowered ceiling height... The latter isn't exactly great and the former is seemingly unavoidable without a compete rework of the subfloor and joist above.

Clarify the work and reference the plans?
 
Soldato
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Ask the builder if he can't explain his plan in less than a minute you are in trouble. Usually you have two options here blue steel with sits on top of red or bolts to the side. It doesn't look like either is possible without modifying the upstairs joists which would actually be the best solution to hide the beam as it would be in the existing ceiling void avoiding boxing in or lowering the ceiling!
 
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Not sure if this is normal, but our Architect plans simply show the steel locations and T joint. The structural calcs then specify the size of the steels. None of the drawings are detailed 3D diagrams of how the steels will join together. I had assumed this was normal, implied, and worked out by the builder?

Anyway, had a chat with them and the plan is to re-hang the joists on to the new 'blue' beam that will be hidden in the ceiling. Sounds like a lot of work (including re-routing of some pipes), but that on them. However, will result in all beams being hidden in the finished room.

Suppose it was an oversight on my part to not drill in to this detail before starting, but its one of those "you dont know what you dont know" scenarios.
 
Associate
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Your not over reacting at all. These are supporting large parts of your house. It has to be right. He’s already lied on what he was going to do - he needs to either deliver or you take him to court. I hope you haven’t paid anything.

Do you really trust this bloke after this? I wouldn’t.

Building control will be keeping a very close eye on this I’d imagine.
 

k3v

k3v

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Well everyone loves a good OcUK drama, so lets see how bad this is.

Fast forward a few weeks, smaller blue beam is in, was told joists being cut, happy days.

I come back one day, and find it like this:
22E2Q3w.jpg
PC37z65.jpg

(it has since being welded, with no additional plates)

I'm no Structural engineer but alarm bells ringing. Building control came out, they are also not happy.
Original SE calcs delivered size of beam and in-web connection.

Apparently it could not be aligned due to floor height. Aka, he put the big beam in too high and cannot back track.

Building control and my architect have never seen a beam connected like this.
Builder claims he has done it before.

Currently its with the builder and SE to deliver more accurate calcs reflecting the joint shown.

Hopefully they can arrive at a plated design that satisfies calcs and building control, otherwise I'll be looking at a huge mess to sort out, already lost confidence in builder, and my own sense of judgement! (How can you get something so fundamentally wrong if you have done these sort of jobs before?)

I crawled the internetz and could only find one drawing showing similar connection, 4 below:
5TGLv9D.jpg

Am I over reacting?

I'm a structural steel draughtsman. If i was drawing that as a bolted connection which is the normal way it would be on what is called a toe plt. This is he best way to deal with the vertical offset between the two parts. The vertical offset looks to large to bolt it together like (4) you need a min .6 of the depth of the supported beam that isnt notched.

The way they have done it by welding them together, this goes out of the window somewhat assuming the weld is good. If its fully welded it may well be structurally strong enough.

An engineer would need to look at it.

Edit: sorry skim read this, if this needs changing in situ, access will be a problem to create a toeplt connection . Which is the best way to creatre a bolted connection
 
Soldato
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I am a chartered structural engineer, and this looks botched. How incompetent does the engineer have to be not to think about the connection detailing. It could have easily been detailed early on properly, as opposed to what's there now.

Not only that, but the fact you whole rear wall is being removed, and only a RSJ installed rings alarm bells to me. I would have expected a rigid steel frame to reinstate lateral stability lost due to the rear wall removal + possibly foundation strengthening (due to width of opening). You might be in luck assuming your neighbour still has their back wall for stability. But i personally would never take such a risk for my clients.

Padstone installation looks terrible too as they are not course into the brickwork to help disperse the load. This could result in cracks long term.
 
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