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Participant

Join Date: Jun 2009
Posts: 3

What beam size

06/12/2009 6:51 PM

Hi All

Can somebody please help me decide.

I need to know the size of the beam to support normal loads over a 4.3m span.

It will need to support 9x3 joists on both sides.

It will have normal dead weight and normal imposed load.

Many thanks.

Qas

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Guru

Join Date: Jul 2007
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#1

Re: What beam size

06/12/2009 7:38 PM

Without a lot more details, most ethical engineers won't answer. Tell about the type of building, the location (building codes), what dead load, what live load?

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Guru

Join Date: Apr 2007
Posts: 577
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#2

Re: What beam size

06/12/2009 11:04 PM

You say normal load. What is the actual weight. 1 Kg, 10Kg, 1 ton, 10 ton, Please specified more on your normal load weight.

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Participant

Join Date: Jun 2009
Posts: 3
#3
In reply to #2

Re: What beam size

06/13/2009 6:23 AM

Hi

Sorry for not being more specific-I am sending a image link.

As you see-I have a massive span with few supporting walls.

We need a beam ,in the red.

This is a loft conversion project in a 4 bedded victorian semi,in UK.

Please also help with joist selection-will normal joists be ok.

The loads will be in the normal range-ie

dead wight =05 KN/m2

imposed weight=1.5KN/m2.

The space will be made into 1 bed room with on suite shower and loo.

Please feel free to advise on anything else.

Many thanks for all the help & advise.

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Power-User

Join Date: Mar 2009
Location: Northeast corner of the sphere
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#7
In reply to #3

Re: What beam size

06/14/2009 11:33 AM

I'm surprised that given what is shown, you can't figure this out. You have an existing joist supporting a double span on the stairway side. If this was built to code, then duplicate it on the other side and double the verticle support all the way down to the slab / basement / pier. Your new span is only going to carry one side, not two.

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Power-User
Engineering Fields - Systems Engineering - Member for some time now, see my profile.

Join Date: Aug 2007
Location: Essex, UK
Posts: 364
Good Answers: 3
#9
In reply to #3

Re: What beam size

06/15/2009 4:33 AM

From Sleepy,

You say that you have a Victorian Semi detached house that you wish to expand vertically.

I am not a structural engineer but believe that you will have to involve your neighbour ,<in the other half of the semi>.

The risk of any failure applies to him as well.

I would have expected your Image to have shown a party wall.

Like the other respondents, I believe that you should/must employ a structural engineer in these circumstances.

Good Luck

Sleepy

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Participant

Join Date: Jun 2009
Posts: 3
#10
In reply to #9

Re: What beam size

06/15/2009 4:46 AM

Hi All

Many thanks to everyone for the comments-I have asked an engineer for a site visit.

Will let you know on outcome.

Thanks .

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Guru

Join Date: Oct 2007
Location: Tulare, CA
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#11
In reply to #3

Re: What beam size

06/15/2009 12:04 PM

So this is to be a weight bearing wall I take it?

You can get laminated beams to do the job. One bean that goes from the ceiling to the top of the doorway will work.

They use laminated beams across front of garages. That's definitely weight bearing

I've also seen 4" x 12" used as a beam across a 30' span with one 4"x 4" supporting at about the 1/3 of the way into the space. This was for a garage and workshop combo with a guest room built above and a 12x12 pitch roof. The person that put that in place did it by himself and there was no sagging but it wouldn't be considered weight bearing.

Your expanse is roughly 14' across, I'd go with the laminated beam and don't be afraid of overkill. It's better to have more then enough strength then not enough.

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Guru

Join Date: Jun 2008
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#4

Re: What beam size

06/13/2009 11:05 PM

If this project needs certification ( or permits, as they are called in this country) these will be of record, and will require a local structural engineer, licensed for practice in your area. He will deliver the calcs and the methods of achieving them. Please do not try to go to a website to obtain YOUR local building codes, and expect anyone to duplicate your specific situation.-Sorry to be a piss on this, but that is what engineers, in your town/county, whatever are, for.--Get certification of design and engineering, then perform the work as specified, have it inspected and O.K.ed, and then you will have no problem with insurance and re-sale---hope this helps (P.S._--if this is a bootleg, do what ever you want--be prepared to accept the consequence, if and when it fails, or if you want to sell) C-MAC

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Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#8
In reply to #4

Re: What beam size

06/15/2009 3:57 AM

Quite. Well said.

Of great value to the Client is the document that describes the calculation for ths sizing of the structure, on the basis of guidance to the builder and to the planning office, and as a statement of warranty that the designed structure is fit for purpose.

It is vital to obtain professional advice, and to pay for the design document.

In the UK,

  • the Building Regulations offices will want to have a copy of this document, to supervise the builder.
  • In the event of a failure, the building's insurers will want a copy of the document to pursue the document originator's indemnity insurance and recover the costs of rebuild.

Anonymous advice from an international engineering forum just will not do!

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Guru

Join Date: Nov 2007
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#5

Re: What beam size

06/13/2009 11:17 PM

This is not a proper question for a forum such as this. The purpose of this forum is to assist members in the understanding of engineering questions, not to solve specific issues such as yours.

Retain an engineer to work out your problem.

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Posts: 13
#6

Re: What beam size

06/14/2009 8:54 AM

Residential construction Codes vary so much here in the states. You must consult your local housing authorities to know what is required in the UK.

Personally, when I do projects like this, I typically build it like a tank. In practice, most people I know exceed minimums for a comfortable margin of safety.

I also caution you: getting someone over the internet to spec out structural members for you is not real smart. You generally can't know their qualifications or track record. Hire a local expert. This is not a difficult calculation. Most 3rd year engineering students can do this fairly quickly. It shouldn't be an expensive venture to hire a professional engineer or building engineer. A Designer can do this as well.

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Users who posted comments:

ba/ael (1); C-Mac (1); Cincy10 (1); Janissaries (1); Jerry New Hampshire (1); PWSlack (1); rwy12 (2); Simon Wan (1); Sleepy (1); TVP45 (1)

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