Due Diligence

[amecENG]

I was wondering how other engineers handle selecting beam sizes for residential contractors.

I recently sized a beam for a residential renovation and ever since I have been critical about how other engineers tackle this problem. In my case I picked a beam and became suspicious about how the contractor planned to connect it and support it. I ended up producing a full engineering drawing sheet with connections, built-up wood columns, baseplates, and footings. Even though I was only asked to select a beam I didn’t feel comfortable about everything else.

My main question is how far should you go as an engineer when someone asks you to design them a beam? Legally, do you have to trace the load path right down to the foundation to make sure everything is OK or can you just select the beam and let the building inspector pick up on everything else.

I know engineers, and sometimes architects, select beams all the time for houses but what prompted this question was that I went to look at buying a house a few weeks ago with a room under the garage. The house was just being constructed so everything was exposed and the garage floor looked very suspect. I questioned the contractor and he said that the floor was designed by an engineer. I agree that the steel beam may have been designed but there is no way that the columns and footings were. See attached pics. This made me think, since I just went through this myself, how dangerous it is to just pick a beam size and ignore the rest.

 

[MiketheEngineer]

I don't usually have a problem with the people I work with on a continuing basis - I know what they do. I have inspected enough of their work.

However, with a new contractor I will either review what they are going to do or draw it up.

 

[Lion06]

I can't tell from the pictures what the size of the center column is. The ends look like they may be bearing on the wall and not using the wood as a column. I only say this because it looks like there is very little bearing length and doesn't seem realistic, and why wouldn't you pocket the beam into the wall?

What size is the center column?

In my limited experience, here is what we typically do. We will do all of the checks that we feel are necessary - right down to the foundations. We will advise the client, with a report, if we feel what they are looking for can be done, and, if so, what may or may not need to be done to make it happen. We end the report by saying that should they wish to proceed we recommend having construction documents produced for use with the renovation.

What I can definitely say is that we would never size a beam without looking at all of the other stuff that goes along with it. We also would not just give a size without all of the constraints that go along with it (span length, loading area, support conditions, etc).

We, as engineers, can't stick our head in the sand and play dumb. We need to understand the load path and make sure every part of it works. Doing otherwise seems like it is inviting trouble.

 

[BAretired]

An engineer is responsible for any design he performs. He is also responsible to ensure that the information is provided to the contractor in a manner which cannot be misinterpreted.

If an engineer gives a beam size to a contractor over the telephone and fails to check other aspects such as lateral bracing or end support, he runs the risk of being sued for damages in the event of inadequate performance or failure to carry the load.

BA

 

[DWHA]

We do follow the load path to the foundation and detail all items unless the client specifically requests the beam only. When this is the case, on our drawing, reports, etc. We state in bold or underline something like "connection & columns by others" this usually covers our end. And most of the time the code inforcer ends up telling our client that the need the column and connection analyzed. So we get the project back and complete it at that time.

Whenever possible, we just do the complete analysis up front. But sometime the client is stubborn and does not want to pay for that.

 

[oldrunner]

Fire the client.

Maybe more of us should do that.

 

[SteelPE]

Usually when I size a residential beam similar to the one in you picture I will size the columns and the foundations as well. It would only take a few minutes to design anyway, so why take the risk of it not being done properly.

While I might not provide a full drawing set, I will usually provide a hand sketch that shows the assumptions used when calculating the size of the beam (house dimensions/ supporting floors/bearing wall locations). Quite often, the calculations and sketches are done on the same sheets of paper (8.5x11) which are stamped and sent to the client for his records and to give to the building inspector.

 

[dhengr]

I’d be suspicious of that builder too! He didn’t even get the moisture proofing (damp proofing) mastic on the correct side of the conc. walls. The last picture shows the stl. bm. bearing on one and a half 2x studs until it settles 1/8"+. The stl. bm. is just long enough (too long) to suggest that someone once thought it should be sitting in a pocket in the conc. wall. The 4th & 5th from the last photos show a built up wood col. which has been standing in water on a 20 - 24" wall ftg., and will remain standing in water on conc. after the bsmt. slab is poured around it. Never mind that those members should be pressure treated, that’s a crappy detail in any case. The built up col. is probably hollow and not connected to the conc. wall either. If any of your photos is of the underside of a garage fl., which you suggested in your OP, that’s suspect too.

If you don’t do the whole beam design, including connections, columns, footings, etc. you get this kind of crap, from way too many builders. And, you should get paid for some field observation too, so that you know they are doing it right until you get to know that contractor, and how he follows direction and plans. They quick forget, when things go wrong, that they didn’t want to pay you to design the cols. and the ftgs. While they may have forgotten your name when it came time to pay you, they will remember it when the owner’s lawyer come call on them.