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walkereng, Consultant
Category: Structural Engineering
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Experience:  Over 30 years of Structural Engineering experience.
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what size laminent beam should i Use to span an 18 foot opening

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what size laminent beam should i Use to span an 18 foot opening for a one story single family home

walkereng :

I can help

walkereng :

Are you removing a wall?

walkereng :

If so is it a bearing walls?

walkereng and other Structural Engineering Specialists are ready to help you
Customer: replied 5 years ago.
yes i am removing a load bearing 2 x 4 wall
Is this an exterior wall supporting roof trusses, or is it an interior wall that has struts coming down from your roof rafters?
Customer: replied 5 years ago.
its an exterior wall supporting roof trusses
What is the span of the roof trusses? What is the slope of the roof? What area of the country do you live in so I can look at possible snow load?
Customer: replied 5 years ago.
we live in snow. but we have hurricanes. it is a 3-12 slope and the span is 13 feet from the center of the roof to the outside wall and the load bearing wall is in the center of these spans. there is an 8 foot sliding glass door opening now with a 2x10 beam and i want to open it up to 18 foot. i think i need 2, 2x12 laminent beams to support the roof trusses. i just need an idea before i hire an engineer.
Usually prefabricated roof trusses span between the exterior walls of the house without any support points in the middle of the span. Are you saying your trusses rest on exterior walls 26' apart? Are you also saying that there is some intermediate support the roof trusses are resting on?
One more question, what is your roofing material?
Customer: replied 5 years ago.
it is a tile roof
Did you see my questions before the roofing type, about the roof span? Can you look at those and answer them? Once you do, I can size your beam.
Customer: replied 5 years ago.
the trusses rest on the exterior walls but there is a center 2x4 wall that supports the trusses. it has an 8 ft opening in the wall now and i want to mive it to 18 feet and i need to support this interior wall with a beam to help support the trusses. it has plywood decking on the roof and ceramic tile. the house is a single story home built in 1970.
I can give you a couple of wood options:
3-1/2” x 16” Versa-Lam 1.7 2650 SP of DF
5-1/2” x 14” Versa-Lam 1.7 2650 SP of DF

These are Boise Cascade products and you can go to the following link to find distributors in your area.

You will need to have your engineer size your support columns and detail all of your connections.
walkereng and other Structural Engineering Specialists are ready to help you
Customer: replied 5 years ago.
i know about the versa lams, 14 and 16" is too thick, if i use steel can it be smaller?
Let me know your depth limit for this beam and then I can size a steel beam for you?
Customer: replied 5 years ago.
12 inches or less. will it be some kind of I beam or a steel truss beam (zig/zag)
You could still use timber.

You could use a double 2-5/8” x 11-7/8” Versa-Lam 2.0 2800 DF

Is this OK, or do you still want me to look at a steel option?
Customer: replied 5 years ago.
see if i understand please....what i am looking at is approx. a 5" x 12" versa-Lam beam or can i use three 1 and 5/8 x 12" beam? what would a steal beam be? thank you for all your information, you have been very helpful.
You can use a triple 1-3/4” x 11-7/8” Versa-Lam 2.0 2800 DF

If you want to use a steel beam, you can use a W8x21 (50 ksi) steel beam. This beam is 5.25" wide by 8.25" deep and weighs 21 pounds per foot of length. You will need to brace the compression flange of the steel beam at a 6' maximum spacing. Your engineer can help you with this.

I hope this helps.
Customer: replied 5 years ago.
this tells me exactly what i need to know and i assume that i have to have at least a 4 x 6 inch post at each end to support the beam? thank you for all your expertise., it has been extremely helpful and i hope to look you up again!
A 4"x6" post should be fine.

Good Luck with your project!
walkereng and other Structural Engineering Specialists are ready to help you

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