I wonder if anyone can help me. I have a bungalow that has an original upstairs room with dormer window. I want to move the wall hangers back about a two feet further into the eave space to create a larger space that I can then sub-divide. However, a structural engineer has said that my existing joists, which are 7" deep and span 4m of the downstairs room, are not up to modern spec.. So providing I leave it as it is, it's OK, but if I want to do any work upstairs, it will need to meet modern spec. and only way of achieving this will be to double-joist, which is wholley impractical and makes the project unfeasible. If anyone has relevant experience or knowledge, would you say this sounds correct?
Calculation of joist requirements for upstairs room
- Thread starter kc010c1857
- Start date
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I work for a structural engineering company and the advice you have been given is 100% correct.
Based on old rules of thumb of 0.5 x span in feet + 2inches = joist depth for a 2" joist so 4m = 0.5x13ft+2inch = 9inches so the joist are under sized for use as rooms as they are.
Sounds like the ceiling joists where designed for use as a loft not habitable rooms.
Based on old rules of thumb of 0.5 x span in feet + 2inches = joist depth for a 2" joist so 4m = 0.5x13ft+2inch = 9inches so the joist are under sized for use as rooms as they are.
Sounds like the ceiling joists where designed for use as a loft not habitable rooms.
Woody, thanks for your enquiry. Walls hangers refers to the timber stud work that the plasterboard is attached to, forming the walls of the upstairs room space. If you need any further advice, please let me know.
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I thought so, just don't know them by that name.
These stud walls may be providing support to the rafters, so if moved, the rafters may be over-spanned. You should check this.
But what is the problem?
Is it moving the wall and supporting it, or the fitting of new joists for the extra bit of floor gained?
If the problem in moving this wall is fitting a new joists for it to sit on, then you can fit a joist at floor level, rather than ceiling level and build the wall off this.
Or form a box beam which will be self supporting. Or I beam and lightweight paramount.
You need an engineer you thinks a bit more past the obvious
These stud walls may be providing support to the rafters, so if moved, the rafters may be over-spanned. You should check this.
But what is the problem?
Is it moving the wall and supporting it, or the fitting of new joists for the extra bit of floor gained?
If the problem in moving this wall is fitting a new joists for it to sit on, then you can fit a joist at floor level, rather than ceiling level and build the wall off this.
Or form a box beam which will be self supporting. Or I beam and lightweight paramount.
You need an engineer you thinks a bit more past the obvious
the hangers arent structural, that's confirmed. the issue is that, although a room already exists, it appears the joists are of insufficient depth. so to enlarge the room, the engineer could not sign-off on basis of existing provision. bottom line is i'm not prepared to do anything structural, so just looking for verification that what he's saying is accurate.
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