Structural Engineers Report - Is this a normal request?

[blasted]

I’m looking to remove a section of load bearing wall in order to open up the kitchen into a previously built lean to extension and I’ve had a report produced by a structural engineer.

The opening is 4m in a cavity wall.

The SE has recommended two 152x152x51 UC with a 200mm bearing at each end.

However the SE has also recommended that a 15mm plate be welded to the entire top surface of the two beams. I understand that the plate welded to the top will reduce the risk of lateral torsional buckling and individual beam rotation by making them act as one as well as distributing the load better. That being said I can’t help but feel that 15mm plate is excessive. It would make the top flange effectively 30mm.

My question is, is this common practise? Speaking with the local BCO he thought it was overkill and not something he’s seen, especially for a small house.

The SE also recommended bolting, but if the beams are welded together I really don’t see the benefit.

 

[tony1851]

He's picked those sizes off the top of his head.
Assume your wall is a conventional cavity wall? Then a more manageable beam size for that span would be a 203 x 203 x 46, with a 250 x 8 thick plate tack-welded to the top flange to pick up the width of the cavity wall.
A 15mm thick plate is just nonsense. And if the plate is intended to prevent lateral torsional buckling, why bolt the beams together?

 

[^woody^]

Bolting the things together does all that.

Does the engineer have shares an Tata?

 

[blasted]

He's picked those sizes off the top of his head.
Assume your wall is a conventional cavity wall? Then a more manageable beam size for that span would be a 203 x 203 x 46, with a 250 x 8 thick plate tack-welded to the top flange to pick up the width of the cavity wall.
A 15mm thick plate is just nonsense. And if the plate is intended to prevent lateral torsional buckling, why bolt the beams together?

Normal cavity wall (102 brick, 100 cavity, 100 block) with roof load and first floor acting down on it and a lean to roof as well. I assume the size was picked as the beams side by side only come in at 314.8 mm meaning less projection (7.4mm which could be picked up by plastering). I don't understand your plating suggestion, could you elaborate please?

Bolting the things together does all that.

Does the engineer have shares an Tata?

Quite possibly.

 

[tony1851]

I don't understand your plating suggestion, could you elaborate please?

 

[blasted]

Thanks @tony1851