Complex kitchen knock-through

5 Feb 2007
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United Kingdom
Considering knocking-through our kitchen/breakfast room and dining room. From a structural engineering perspective, the job doesn't appear to be straightforward since we'd be knocking-out a load-bearing corner.

Hopefully, the attached pics will make things clear... the breakfast room is an extension off the back of the kitchen that was added sometime in the 80s, I think. You can see the RSJ that was added on the old external wall. The breakfast room extension abuts the external load-bearing wall of the dining room and I'd like to knock through the breakfast room into the dining room and the kitchen/dining room wall.

Anyone care to speculate on the feasibility, what would be involved and a ball park cost for the building work to 1st fix?



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You would need 1 stonking great steel 1 way and 1 shorter slightly less stonking steel going into it.

The increased load at the ends of the big steel may be too much for existing footing so could need concrete pads.

Cost is very difficult to know, it depends on whats involved, if I had to guess I would say £5k to £10k.

Theres a lot involved, the steel thickness might mean you need the steels to go up into the ceiling, so that means stripping out 1st floor joists, possibky re routing plumbing and electrics. Supporting walls may need sections re building with concrete blocks.
Beg to differ here - it's a common 'T'-shaped layout and generally straightforward when done by a competent builder. The longer beam can usually be a 203 x 203 with a slightly wider plate tack-welded on top to pick up the cavity wall. The shorter ones can usually be 152-deep beams, 1 under each skin, and they sit on the bottom flange of the main beam.
Generally, new pad foundations are not necessary as the load disperses through the existing masonry, but if the main beam is resting on a short length of wall, that may need to be rebuilt.
Agree about the floor spans; each case is different but a competent builder can use joist-hangers etc to minimize the downstand.

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