Follow-up: Question about ‘lateral support’ needed for a center beam

(I posted this a few months ago and got a few good responses, but I also slightly mis-described the scenario; it’s better than what I described. I tried to get a structural engineer to come out, but none of the 6-7 I called would return my call for a simple consultation, and the only one who did was not offering that service and only provided full-scale plans. My sense is that it is safe but am looking for additional opinions.)

This is for a 1.5 storey home with a finished attic/second storey that is basically three structurally independent buildings (with basically three separate foundations) put together into one structure (adjoining buildings were built in the 1960s and early 70s).

The middle structure was built in 1930-1940 has a 28×20 footprint. It’s connected to another building (same address) with no foundation wall in between them. The center beam spans 20 feet. On one end it’s supported by a post of four 2x8s (about 5′ high, with a concrete pier below them) bound together with several very large bolts.

There are a number of 2×4 stud walls in the basement b oth parallel to the beam and at different areas of the basement (see attached image), which have their top plates drilled into the joists. There is also a concrete-filled lally column about 6 feet after that, then a 4×4 post (that is itself bolted to a perpendicular stud wall). See attached image showing what is supporting beam and distances between. The center beam is off level and twisted maybe 3-4 degrees (we thought it was recent, hence the 4×4 to try to block any further movement), but this seems to be a renovations error that happened more than 50 years ago with no movement since, no cracking/splitting of beam, etc. The floor joists are I believe true 2x10s, possibly 2×8, with many pieces of ‘blocking’ between them. The carrying beam is a solid-wood true 6×12 beam that I believe is the original and about 80-90 years old. All wood, joists and beam, is in very good condition.

The current plan is to cut out a fairly large basement window in the foundation wall directly next to the center beam (about 3-4 inches away), which will involve cutting about 2 feet down and about 3 feet across. Due to the landscaping this would get quite a bit of light and improve the feel of the finished area a lot. So the center beam will continue to have vertical post support from the concrete foundation wall, but will not have much next to it on one side going down two feet; only a half-block of masonry block (see diagram; the one with the slash it just indicates concern since this will be the only half-block with the full weight of the beam on it).

*My question is, is the vertical ‘post’ support provided by the foundation wall the only real consideration, or in normal circumstances can the adjacent portions of the wall come into play in support for a center beam? (We had one very minor earthquake about 10 years ago that destroyed no buildings I know of, and that’s the only one I’m aware of in last 30+ years.) Also, are half-blocks (especially if we leave both the middle cross members intact and not just one) as structurally sound as full blocks or is there any vulnerability here?*

As potential overkill (?), we’re considering adding another lally column just before the foundation wall (with a piece of thick angle iron bolted on to hold the beam), so that less weight is potentially resting on foundation.

We may be overthinking this – which is what a contractor I showed it to (not necessarily guy doing job) seemed to think, and scoffed that there was an issue with cutting for the window – just thought would ask for any input. [Beamwindow](//muut.com/u/brownstoner/s1/:brownstoner:vtA4:beamwindow.jpg.jpg) [Beamwindow2](//muut.com/u/brownstoner/s3/:brownstoner:pkdk:beamwindow2.jpg.jpg)

neelazermi

in General Discussion 4 years ago

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Guest User | 4 years ago

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I don’t mean they overcharge but it can induce sticker shock that someone wasn’t expecting.

hkapstein | 4 years ago

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It’s a matter of the situation, but I’m not sure I’d agree engineers charge a lot. A few thousand can often get you engineering plans, and sometimes engineers save money by using a better design than a contractor proposed.

Guest User | 4 years ago

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With anything structural err on the side of caution. Engineers charge a lot and there is always the temptation to skip but not worth it. Imagine later when the walls are shifting and pulling the side wall of the neighbor along. It would be way worse.

neelazermi | 4 years ago

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Yes agreed. May have been fine as is, but the expense will definitely be filed under better safe than sorry.

hkapstein | 4 years ago

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It sounds like you’re getting your money’s worth.

neelazermi | 4 years ago

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Just to check in. Structural engineer checked it out yesterday. Was basically on the fence about whether something needed to be done, and suggested it may well be possible to get away with it as is. Hasn’t done the load calculations yet but tentatively recommended the following as precautionary measures:

A) Steel header/lintel over window to support joist above
B) Filling the hollow CMU cores below the beam and the CMUs adjacent to those blocks with grout/concrete so that load transfers into footing, or installing a post right next to foundation wall and ‘doweling’ it to foundation wall, which I understand the basic concept of but haven’t seen done.

I’m assuming that doing this may reduce the workload on the adjacent portions of the wall (which won’t be there on one side), so maybe that’s where the shear force considerations come in. I directly asked him about that issue and he didn’t really get into it and basically just said ‘we want to direct/tie the load into the footing.’

Guest User | 4 years ago

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Agree with Urbandad, don’t risk it. Shear force is a factor so ask an engineer.

hkapstein | 4 years ago

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I don’t think you should make this decision based on forum posts. There could be questions about whether that foundation wall is properly supported to begin with, or has additional loads on it that may affect the situation, or other characteristics that would make this operation risky that we can’t see. I’d talk to your contractor and see if he knows an architect or engineer who can consult.