Loft Conversion: do beams have to be closed up to run joists across them?

LikeMyHome · 18 Sep 2020

Of course this is a joint wall.

johnny2007 said:
Usually, you would dig into the wall and encase the beams into it (with spreader plates).

I understand that was the orinigal intenstion, but the wall turned out to be only half-a-brick thick, and that didn't work out.
Hence joiners went for hangers.

johnny2007 · 18 Sep 2020

Don't know, I would've used some sort of belt and brace, metal bracket underneath for example.
The holes to fix those masonry joist hangers are close together and bricks can fail, especially under natural vibrations of a floor.
At the very least I would have a 4x4 (or 2 of 4x2 together) bolted underneath the beam and spanning 4/5 foot so to have the fixings spaced out.

LikeMyHome · 18 Sep 2020

This doesn't tell me much be I'll pass this to joiners when they come to continue the works, thanks!

cdbe · 18 Sep 2020

Ok. A "designer" who can produce detailed technical working drawings (for your builder, so he won't need to "see what arises") and for approval by building control, including any structural calculations required.

Personally I wouldn't want to "see what arises" if that joist hanger (or the bit of brick it's sat on) gives way. Maybe the joiner does a bit of structural engineering on the side and it'll all be ok.

Presumably this is being done on a building notice? It might be an idea to let BC know where you are at before you go too far in the absence of the supervising builder.

LikeMyHome · 18 Sep 2020

cdbe said:
Ok. A "designer" who can produce detailed technical working drawings (for your builder, so he won't need to "see what arises") and for approval by building control, including any structural calculations required.

I believe that has been done by architect, the builder calls him and ask to calculate this and that, but we never saw the drawings or calculations - only in wording from our builder that architect says we need so many timbers of such a size etc.

cdbe said:
Maybe the joiner does a bit of structural engineering on the side and it'll all be ok.

I strongly hope so - there're 2 joiners working together, both in late 50's and seem/sound very experienced and confident in what they do.

cdbe said:
Presumably this is being done on a building notice?

Both building and planning are in place. BC just started and had a first visit this Monday.

cdbe said:
It might be an idea to let BC know where you are at before you go too far in the absence of the supervising builder.

Our buidler is the main contact point for BC and we're not doing anything to bypass either of them.

tony1851 · 19 Sep 2020

LikeMyHome said:
I believe that has been done by architect, the builder calls him and ask to calculate this and that

It's not generally in the architect's remit to 'calculate this and that' -that's an SE's job.

Perhaps it's me, but I find it difficult to follow what's going on with this floor. If you are supporting the floor joists off two main bearers - and are supporting those bearers off brackets set into the 1/2 brick wall - those brackets would need to be properly designed to account for the crushing strength of the brickwork etc.

LikeMyHome · 21 Sep 2020

Thanks SE visit is being arranged for.

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Loft Conversion: do beams have to be closed up to run joists across them?

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