Cracks appearing after 5m RSJ installation and bi-folds

[tony1851]

The nearest standard section to those sizes appears to be a 203 x 203 x 86, which is substantial, but without knowing the disposition of the load above, it's impossible to say whether the cracking has been caused by deflection (normal down-ward bend of the beam) or poor support/removal of the props.

OP hasn't said if this was designed by a SE, which it should have been: or if Building Control have been involved, in which case they would probably insist on justifying figures for the beam.

 

[Leofric]

Inner leaf is partially supported by the steel beam ! How much of the blockwork is hanging over the edge of the beam ?
Like Wessex101 I can't quite make sense of the arrangement.
Structural work like this should have building regs approval and calcs done by a structural engineer then at least the construction details should be correct and sorted before work starts on site.
' The RSJ has been installed onto two pieces of cut steel and not padstones due to my exposed brick outer wall' - outer skin of brick usually is exposed !
Is there a photo showing the head of the opening looking from outside to show how the beam is faced ?

 

[tony1851]

@op; you really - REALLY - need to speak with your building inspector before this goes any further, assuming a Building Regulations application has been made?

 

[ClydeB]

@tony1851 Yes the RSJ was speced out by an SE and the BC came and signed off on it once installed.
They didn't go round with a level or anything and it was a quick review of it on his day off.

 

[tony1851]

@tony1851 Yes the RSJ was speced out by an SE and the BC came and signed off on it once installed.
They didn't go round with a level or anything and it was a quick review of it on his day off.

So is it a normal 275 cavity wall supported on a 203 beam?

 

[wessex101]

So the bearing plate to the inner leaf is sat on thin air and the "builder" has just face pointed it. The infill block is also just resting on the bearing plate with no mortar bed. For the life of me I cannot figure out what is holding up the inner skin above. How the hell did this get signed off by building control?

 

[ClydeB]

@tony1851 I've uploaded a picture of the measurement of the outer brick skin to the inside blockwork.
The blocks are approximately 120mm thick and 60mm of this is not being supported by the RSJ.

@Leofric I've uploaded some pics to this msg and also more uploaded at the initial link.

 

[tony1851]

If the inner blocks are 120 thick, and they overlap by 60, then structurally that is not acceptable. The old rule of thumb is that you could overlap a skin of masonry up to 1/3 its thickness, so the maximum overlap in your case should be no more than 40mm.
It is astounding that your building inspector has not picked up on this.

 

[wessex101]

The photos and the wall build up do not tally. Is that facing brick to the outer leaf or brick slips? If they are facing bricks the wall must be considerably thicker than 300mm.

We are just going around in circles here. You need to get on the phone to the structural engineer and get them to come out and take a look.

 

[^woody^]

I wonder if it will come down with the decorations on 6th January?

 

[Leofric]

I agree with what the others are saying - this is not good building practice. There should be a dpc cavity tray over the head of the opening with weep vents at 450mm centres -can't see any in the photo. The bricks on end are usually 215mm high but appear to sit in the steel beam ! As for cold bridging and insulation! If the structural engineer could draw a section through the head of the opening to show exactly what has been built and approved by building control I think it would get pulled to pieces on here.
The usual detail for a steel beam over a fairly large opening in an external wall is to fully seat the internal leaf of blockwork on the top flange and support the outer leaf of brickwork on a steel plate welded to the bottom flange. Even then you need to minimise the risk of condensation through cold bridging across the fairly thick continuous bottom plate by using insulation and a vapour barrier.
ps the SE might have calculated the beam size but I can't believe they envisaged this construction.

 

[tony1851]

As above, we don't really know what's going on here - some sectional details, or view of the SE's figures and assumptions would help.
Very surprising building control have OK'd it with such a big overhang.
And over time, rust-expansion will play havoc with the outer skin.