UB Size

rickb72 · 3 Jan 2013

Hopefully this is the right place to ask the question - apologies if not.

A SE has spec'd UB's for enlarging an window opening between an existing ground floor room and an extension but my builder is querying them as they seem very large and over spec'd.

The proposed span is 2.5 m with calculated dead load of 11.6 kN/m and imposed load of 4.5 kN/m. He has spec'd 2 nr. 203 x 133 x 30 UBs.

Any advice appreciated.

luisdesign · 3 Jan 2013

Have you brought up the query with the Engineer?

Engineers will allow for a margin of error but I would take their word over your builders. Bring it up and see what they say - it may have been a simple error or the engineer may simply have more information on loadings than the builder is taking into account!?

noseall · 3 Jan 2013

Why the wide (133mm) flange, is this so that the beams can be butted together when bolted?

30kg is fairly hefty and seems a lot for a 2.5m span.

Builders don't usually question S.E. decision making process, but it may be worth a call.

jeds · 3 Jan 2013

Massively over the top. A pair of 178x102s would be over the top. How much did the SE calcs cost?

tony1851 · 3 Jan 2013

Those beams specified are way over the top. On that spanand assuming no abnormal loading, I would have said two 7" x 4"s but Jeds beat me to it.

rickb72 · 4 Jan 2013

Thanks for the replies so far, i feel re-assured thats it's not just me thinking it is over the top.

Its a little complicated because my builder is a friend and is basically of the opinion I am having to pay extra for something I do not need. They have done a lot of much bigger jobs and the SE they use has never spec'd anything as big as these (I unforetunately used a SE who works in my office!!)

I have spoke to the SE who is going to have a look but everything he has spec'd so far has been way over the top e.g. 300 x 700 foundations with A393 mesh for a simple 2 storey extension on good ground.

tony1851 · 4 Jan 2013

rickb72 said:
everything he has spec'd so far has been way over the top

Unfortunately some SEs overspec things to cover themselves, but it simply loads the cost onto the job. It means in essence that you are paying a premium for the engineer's laziness or lack of confidence.

^woody^ · 4 Jan 2013

When using an engineer, tell him that you expect him to lift the damn thing up and in. Then you will get the lightest beam possible

There is a wide line between over specification, and plain lazy incompetence - and this "engineer" is on the wrong side of it. Assuming that there is no point load though!

JMSD · 6 Jan 2013

It does sound over the top, ask your engineer if there is some reason for it I would suggest. Perhaps ask him why you can't use an off the shelf cavity wall lintel.

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UB Size

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