Dispute between SE and Builder

24 Oct 2017
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United Kingdom
Hi all,

We have had an extension done and have recently knocked through and put in a large steel.

The builder (and project manager) has put the steel on a padstone and the padstone is suspended across the two leaves of the cavity wall. The cavity wall that it is sat on used to have a closed face as it was a nib/return that we cut back to reduce the amount it stuck out. Now the cavity is exposed.

Building control said that this is not acceptable and the SE has also agreed that it is not acceptable and that his calculations were based on that return being closed. He specifies in the Calculations the following:

Inner Leaf: assume Blockwork = 3.6 N/mm2
Assumed full bearing on cavity wall
Try End Bearing = 150mm (minimum)
Steel Beam <B1>, 203x203UC, steel ‘in-plane’ of wall

The builder is saying it is not his fault as he has built it to the calulations and has 150mm bearing and is refusing to resolve the issue at his cost.

I feel that 'assumed full bearing' means that the padstone is not suspended between two cavities but is fully resting on something and has no void underneath it.

Am I correct in this? I am now stuck between two professionals claiming it is not their problem.
Ultimately the builder has also been paid a management fee, so I feel that the buck should stop with him to get his work signed off by building control.

Any thoughts and advice would be much appreciated.
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Have you got a photo or a drawing of how the beam is actually sitting on the wall?

Just from your text, it initially seems that you may all be 1/3 responsible, and the inspector might be wrong in his request.
It's almost certainly not an issue. If there is a 140 deep padstone between the underside of the beam and top of the brickwork, it will easily straddle the cavity.
If the cavity was originally closed, the offcuts which form the closers would have contributed almost nothing to the bearing strength; and of course the two skins would not be bonded at that point anyway, so slenderness of the individual skins would not have been an issue.
A drawing or pic would shed some light.
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Would love to see a photo of the installation. The OP has not said exactly what it is that the SE and BCO are now asking for. Full bearing on a cavity wall means to me the padstone bears across both leafs of the wall fully and as you would expect from a cavity wall there is a gap between the leafs that simply gets straddled by the bearing padstone.

I would be inclined to ask who made the change to the nib/return as I assume this was on a drawing and there may be someting else there that has impact on the work. If "we cut back" is you asked the builder to do it and he has then whatever additional work is involved may be a variation and should be valued as necessary to take account of the change. While accepting as Project Manager the builder has to sort it out the OP may need to pay for it.

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