Loft Steel bearing

[tony1851]

The C24s are not always easy to come by.
Your joists are only carrying normal domestic loading of 1.5kN/m2, so the
TRADA span tables can be used. The Inspector will have to accept them as adequate as long as they fall within the limits, regardless of what the SE has put in his figures. (The Inspector won't even have bothred to go through them).
Don't forget to double-up the joists if any support a partition or bath etc.

 

[RonnyRaygun]

Is there any argument for over specifying ? if not then thats a mistake surely, even myself being a laymen has worked out I only need C16's, surely if there is a reason I should have been consulted before it went to planning ...

You might use deeper joists than needed if, for example, it makes it easier to hide the steels in the floor/ceiling void. I can't imagine that would be an issue in your situation though, as I would imagine the ceiling will not be touched.

You might spec deeper joists if you plan to tile your en-suite. By doing this deflections are minimised and you are less likely to find grout or tiles cracking.

However, I can't think of any good reason to use C24 rather than C16 in this case. It's usually only done where the depth of the joist is limited and C16 won't quite work.

 

[frank999]

Many thanks for the replies.

Yes, I'm wondering how critical the BC inspector will be.

With a 203mm high steel, and a 200mm joist - how does my 'architect' or structural engineer expect me to install the joist so its proud 10mm above the steel - to allow for shrinkage, do I pack out - and with what, or order a 225mm joist ? any suggestions.

The purlin wall sits on one of the joist spans - the calcs spec a:

Span 2800mm
Spacing 300mm !
Dead full UDL 0.300kN/m
Imposed full UDL 0.450 k/m
Dead point load 1.110kN at 1900 mm
Imposed point load 0.450 kN at 1900mm

Does that still need a C24 ?

Thanks