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walkereng, Consultant
Category: Structural Engineering
Satisfied Customers: 2546
Experience:  Over 30 years of Structural Engineering experience.
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I wish to replace three 2x10 wooden floor beams with an I Beam

Customer Question

I wish to replace three 2x10 wooden floor beams with an I Beam to create a bit of free space close to the beams.

What size of I Beam, (S and/or W) would be the equivalent of the three 2x10 wooden beams (Southern Pine) for domestic floor beam support with span of 9' 6" supporting main floor of domestic residence above.

If I reverse engineer the choice of the existing three 2x10 wooden beams it would appear these had been chosen from wood frame construction tables (Canadian) for floor joist support length 'L' of 12 ' (1/2 of 24') built with 2x12s on 16" centres, as are in place now.
Using those tables the best case span for the Floor Beam Span for the three 2x10 Southern Pine wooden beams is 10' 6" for good quality to about 9'6" for lesser quality lumber. Actual span is 9' 6" between upright supports confirming the choice that had probably been made for the existing wooden beams.
Submitted: 4 years ago.
Category: Structural Engineering
Expert:  walkereng replied 4 years ago.

walkereng :

I can help

walkereng :

I have attached a file, can you take a look at it and answer the questions at the bottom of the sheet? Your answers will allow me to accurately model the loading and size your beam. Thanks


walkereng :

I am going to switch over to the Q&A format and we can continue with the e-mail process. When you come back online, just reply to this last e-mail (use the e-mail account that you gave to JustAnswers) to tell me you are back. You do not need to hit the "Accept" button until we are complete and you are satisfied. Thanks.


Customer: replied 4 years ago.
Hi Walker, I replied to your email by simply replying to your email, not sure if that gets routed to you properly/ automatically?
Paul (question ID# XXXXX)

Here is the answers again in case that email didnt redirect correctly:

looked at your pdf.
I'm not able to edit the pdf, but to answer what you need from that diagram:
QNs1, 6, 7 and 8
This is a bungalow residence (1 story with a basement)
THe new beam is in the basement, so it would be a new beam 2 if there is no second story
Floor joist span #3 and #4 above the new beam are both currently 12 feet.
Span #3 will be reduced by a new supporting wall in the basement parallel to the new beam, so span #3 will be reduced to be only 6 feet before this new beam replacement goes into place, so that would reduce the size of the new beam slightly.
Just FYI the new supporting wall is being added for functional /room division reasons in the basement as well as to remove the weight of a bath tub from the floor area supported by joist span #3 above new beam 1, so that new beam 1 will not see a bath tub load on the floor spans above it (and an upgraded bath tub is being added in future that will not affect what we do today as it will be isolated by that new supporting wall).
QN 3. Roof trusses transfer load to interior walls.
Trusses are factory built with metal plates.
Residence is in the city of Ottawa in the province/state of Ontario, Canada.
Roofing is metal (so snow tends to slide off more than on other roof types - which is I assume the point here).
Note Floor joists for span #3 and #4 are 2x12" on 16" oc
Hopefully that covers what we need?

Expert:  walkereng replied 4 years ago.
I apologize for the delay, I got sidetracked yesterday. I will be working on your question this morning. I will get back to you shortly.
Expert:  walkereng replied 4 years ago.
For your 9.5' span you can use:

W8x13 (50 ksi) steel beam. This beam is 4" wide, 8" deep and weighs 13 pounds per foot of beam.

You need to make sure you provide solid mechanical connections between each of your existing 2"x12" floor joists and the top flange of the steel beam. If the floor joists will rest on top of the steel beam, you can bolt a timber nailer to the top of the top flange to connect your 2x12 floor joists to.

You will need to have a local engineer size your supports, detail your connections, and check the load path to your foundation.

Let me know if you have any other questions.
walkereng and other Structural Engineering Specialists are ready to help you
Customer: replied 4 years ago.

Expert:  walkereng replied 4 years ago.
Good Luck with your project!

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