roof/ceiling I-beam spans and load capacity

warmbrus · 09-17-2011, 07:30 AM

I would like to know what size I-beam or if I can use a 3" or 4” heavy steel channel to span a 20 foot portion of the roof. The home is a 40' x 22' modular home. Down the center of the 40' length are 3 piers to support the floor and 3 respective vertical posts (4x4) that support the roof (i.e. a support every 10 feet).

What I would like to do is remove one of the vertical roof supports. Therefore, I need to support a 20' span of the roof without a center support. The roof is a cathedral type roof (3/12 pitch) and the height at the center of the roof is about 11’. I would like to use steel channel MC 3 x 7.1# or MC 4 x13.8#. I was thinking of welding two channels together to make a box beam or go back to back in an I-beam configuration. Thanks.

J. Wayne Armbruster
email: wayne.armbruster@gerdau.com - or – wayne.armbruster@gmail.com

bob22 · 09-17-2011, 08:05 AM

You need an engineer, stamped and approved plans, and a building permit. No one here can judge this from a far IMO.

Joe Carola · 09-17-2011, 08:10 AM

Quote:

Originally Posted by warmbrus

I would like to know what size I-beam or if I can use a 3" or 4” heavy steel channel to span a 20 foot portion of the roof. The home is a 40' x 22' modular home. Down the center of the 40' length are 3 piers to support the floor and 3 respective vertical posts (4x4) that support the roof (i.e. a support every 10 feet).

What I would like to do is remove one of the vertical roof supports. Therefore, I need to support a 20' span of the roof without a center support. The roof is a cathedral type roof (3/12 pitch) and the height at the center of the roof is about 11’. I would like to use steel channel MC 3 x 7.1# or MC 4 x13.8#. Thanks.

J. Wayne Armbruster
email: wayne.armbruster@gerdau.com - or – wayne.armbruster@gmail.com

No one here can possibly tell you this. You need to contact the modular company that built your house.Modular homes are completely different. Either way you would need an Architect or Engineer to help you for something like this.

Daniel Holzman · 09-17-2011, 08:25 AM

Are you the contractor or the owner? If the contractor, you certainly can afford to hire a structural engineer to design the job, you pass the cost along to the owner. If you are the owner, I am guessing you have some channel left over from a previous job, and want to reuse it. Reuse is good, we like to save the planet. However, as previously noted, you need professional help, a hands on visit, and careful evaluation of the options. A channel is normally not used individually as a bending element because of asymmetrical bending issues, generally they are used back to back in this type of application, or else an I beam or H beam is used. But your engineer will discuss these issues with you, and will no doubt make the right recommendation.

warmbrus · 09-17-2011, 09:26 AM

Quote:

Originally Posted by Joe Carola

No one here can possibly tell you this. You need to contact the modular company that built your house.Modular homes are completely different. Either way you would need an Architect or Engineer to help you for something like this.

Thanks for the advice, I will have a PE review my design/idea, but was wanting to see if some contractor or engineer online could tell me if I' in the ballpark. My intentions were to use the MC 3 or MC 4 as a box beam or back to back like an I-beam. Later today I will post some pictures of the current modular design if there are any further comment. Thanks again.

J. Wayne

warmbrus · 09-17-2011, 09:36 AM

Quote:

Originally Posted by Daniel Holzman

Are you the contractor or the owner? If the contractor, you certainly can afford to hire a structural engineer to design the job, you pass the cost along to the owner. If you are the owner, I am guessing you have some channel left over from a previous job, and want to reuse it. Reuse is good, we like to save the planet. However, as previously noted, you need professional help, a hands on visit, and careful evaluation of the options. A channel is normally not used individually as a bending element because of asymmetrical bending issues, generally they are used back to back in this type of application, or else an I beam or H beam is used. But your engineer will discuss these issues with you, and will no doubt make the right recommendation.

Thanks for the reply. I am the owner and this is a cabin I am refurbing. You are exactly right I have acccess to MC 3 & 4 (I am the Engineering manager at a steel mill) and I was thinking either box beam or back to back. I intend to have a PE review my idea/design, but wanted to see if some engineer online could do a quick calculation and tell me if I'm in the ball park. Thanks again for your comment/advice.

J. Wayne