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walkereng, Consultant
Category: Structural Engineering
Satisfied Customers: 2827
Experience:  Over 30 years of Structural Engineering experience.
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I have a question /structural one available?

Customer Question

I have a question for civil/structural one available?
Submitted: 1 year ago.
Category: Structural Engineering
Customer: replied 1 year ago.
How far can you cantilever (?) a 2x8 16 past a beam? ...4 feet of the 16 feet is sistered to the original house floor joists, the beam sits 9' 6" out from the house...beam is grx fastened to 6x6 treated is a post addition with sonotubes as footings...sonotubes are 12" round sunk 4'
Customer: replied 1 year ago.
I currently have 28" cantilevered past the beam, the beams are 2x10's...The addition measures 12' X 32'
Expert:  walkereng replied 1 year ago.

I can help.

Do you have any pictures you can share with me?

Customer: replied 1 year ago.
Does this help?
Customer: replied 1 year ago.
The original house joists were 2 foot on center I have added additional floor joists to make the floor 1 foot on center
Expert:  walkereng replied 1 year ago.

I am just leaving my office right now, can I get back with you a little later this evening after I get home?

Customer: replied 1 year ago.
Basically what I need to know is a 28" cantilever allowable/acceptable based on my info provided as well as the sonotubes for footings...
Customer: replied 1 year ago.
of course...have a safe trip home!
Expert:  walkereng replied 1 year ago.

Thanks, ***** ***** you soon!

Expert:  walkereng replied 1 year ago.

1. So you have 2x8's spaced at 12" o.c.?

2. What is the height of your framed in wall on your cantilever?

3. How will your ne roof be framed into your existing roof?

4. What city and state are you in for possible snow load?

Customer: replied 1 year ago.
2x8x16 12"o.c....10' wall...gable roof tieing into existing in Michigan City of belleville
Expert:  walkereng replied 1 year ago.

I’d like to point out that a Professional Engineer’s standard of care typically includes a site visit to assess field conditions and get an overall understanding of the structure. This can obviously not be accomplished through the internet. The information provided here is meant for planning purposes only (general sizing and budgeting) and is based on the information provided by you. All loading cases considered are for vertical loads only, no lateral analysis has been completed. The information should be verified by a professional engineer who can visit the site to ensure that potentially important information has not been overlooked or omitted.

Your cantilever of 28" it too far. Most designs limit a cantilever like that to 24" as the absolute maximum. You could possibly sister an additional 2x8 next to each existing 2x8. I would use a 6' long 2x8 as the new sistered member and you will need to through bolt these together with 1/2" diameter through bolts spaced evenly along the joists.

Expert:  walkereng replied 1 year ago.

If you feel you have received a satisfactory answer to your question, click the Rating button that is appropriate. Experts are credited for each appropriately Rated answer they provide. If you have additional questions, please let me know. Thanks

Expert:  walkereng replied 1 year ago.

Let me know if you have any more questions

Expert:  walkereng replied 1 year ago.

Let me know when you come back online and if you still need help.