Messages and Online Forum Q&A

Re: Replacing a cinder block wall

From: info@builderswebsource.com
Category: Structural
Remote Name: 63.198.181.43
Date: 01 Feb 2002
Time: 09:37 PM

Comments

We have a good picture of what you're trying to achieve. First, without knowing all the loads on the beam, we cannot compute the size. However, for a typical 1-story home of average size, the beam you describe sounds reasonable (W8 x24). Keep in mind, however, that snow loads, roof loads, 2nd story loads, etc., could materially change the calculation, impacting the size of the beam required to provide a safe and functional solution. In addition, the amount of acceptable deflection varies greatly. Meeting minimum code is one thing, but having a stiff floor above that doesn't sag is another. We generally recommend over-sizing a beam so that you will enjoy a very stiff floor.

As to your question about the cement block wall being able to handle the load, concrete is very strong in compression -- typically at least 2,000 PSI or more. Assuming your wall is properly reinforced with steel and filled solid with grout (you must verify this), and assuming each end of the beam has sufficient load-bearing surface contact, the then cement wall should readily handle typical loads. For example, with a beam that's 6" wide....and 4" of load-bearing surface on each end, that would provide you 24 square inches of surface contact. Assuming even a conservative 1,500 PSI rating, each wall could handle about 36,000 pounds of load....which is probably way more that you'll see in this case.

Keep in mind, though, that the way you anchor the steel beam to the concrete walls is just as important. You can't just set it up there. A licensed structural engineer should provide you with specific structural recommendations and engineering details, including how to anchor the beam, how to laterally support the beam (to avoid twisting)...and how to size the beam to carry the correct loads while maintaining a very stiff floor above. Sometimes the beam is specified with a preset camber to help compensate for dead loads. That way you have a straight beam under loaded conditions. Unless your steel beam supplier has a structural engineer on staff, we would recommend double-checking all measurements and calculations with a licensed engineer.

Furthermore, the wall itself may need additional steel reinforcement to prevent structural damage during an earthquake or heavy winds.

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