Steel beam on wood post

[A_Rex]

My architect is telling me that he will not allow me to install a horizontal load-bearing steel beam that is supported by 3 2x6 existing vertical posts on either side. The posts sit on the foundation. I am being told that a steel beam can only rest on a steel post. (Something to do with different rates of expansion and contraction?)

I would prefer to have them supported by these wood posts, rather than rip out most of the wall to install vertical steel posts.

Should I be pushing back on getting him to allow me to rest the horizontal steel beam on vertical wood posts?

Based in Toronto, in case temperature variation is a factor...

 

[Enable]

If this is an interior (heated) application such as an existing family dwelling then thermal effects will be negligible. If anything vertical steel poses more of an issue in that regard since it wont expand at the same rate as the wood framed wall. Anyhow, you can absolutely place a steel beam on wood columns but detailing the connection can be tricky to ensure proper torsional restraint.

See many eng tips threads on the topic

Thread 1
Thread 2
Thread 3

And this one where you'll find the following detail from KootK

 

[dauwerda]

Yeah, steel beams are supported on wood posts all the time in residential construction.

 

[phamENG]

(Something to do with different rates of expansion and contraction?)

Haha. All I can say is kudos to his previous engineer who trained his architect to let him use whatever kind of column he wanted.

There's nothing wrong with using a steel column. If you are comfortable with the loading and the connection, then explain to the architect that

a) thermal variation inside a conditioned building is minimal and, besides, the beam and column are orthogonal to one another - who cares if they expand/contract at different rates? The bigger worry there would be the wood nailer on top of the steel beam. But there isn't a worry there. (Maybe don't bring that part up...)

b) the capacity of the wood column is sufficient to carry the load. Steel is rarely needed in residential for strength...it's usually for deflection concerns over long spans. The reactions are usually quite manageable.

c) if you really want me to use a steel column, I will. But it will likely be more expensive for your client.

 

[dik]

In our house in Oshawa, the steel beam supporting the upper floor loads was bearing on 2x4 studs, only by an inch or so... and no connection/attachment other than framing around it. There is nothing wrong with steel bearing directly on wood unless there may be thermal issues for condensation/dryrot. In the longitudinal direction shrinkage of wood is minimal, and not normally considered.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[80PercentTruth]

I've used that detail from Kootk several times with the bottom beam tab which slides into the gang stud pack or engineered wood post bolted into place. One builder I work with cuts off the bottom tab of the beam and simply rests the beam on the column claiming that the joists that run above the steel beam will brace it. That is not a solution I'm willing to seal as I prefer a positive connection.

One thing you absolutely have to watch out for when using wood posts is bearing on a wood sill plate. For high loads, the 500 psi compression perpendicular to the grain for SYP will be insufficient to transfer the load and avoid crushing. In these situations, I generally oversize the post to spread out the load or use PT LVL sill plates. Bearing becomes the item you have to start chasing especially if the post is located on an upper level.

"Engineers only know about 80% of the truth, the next 10% is very difficult to achieve, and the last 10% impossible. If we are bound to be wrong, we may as well be wrong simply and conservatively."

 

[phamENG]

or use PT LVL sill plates

Hold the phone! Your profile says you're here with me in the Old Dominion. Are you telling me there's a reliable source of preservative treated LVLs in the state? If so, where?

 

[80PercentTruth]

@phamENG

You can get PWT Treated LVL from 1-1/2" x 3-1/2" up to 1/2" x 11-1/2". For a recent project, the contractor was able to find them at a local 84 Lumber location. They can also be special ordered as well -- if you try hard enough, you can find it. LVL sill plates are a must-have in the toolbox for the bigger steel beams with longer spans at L1.

https://pacificwoodtech.com/wp-content/uploads/2021/02/20210217-PWT-Treated-Sill-Plate-Flyer.pdf

"Engineers only know about 80% of the truth, the next 10% is very difficult to achieve, and the last 10% impossible. If we are bound to be wrong, we may as well be wrong simply and conservatively."

 

[phamENG]

Thanks. I'm familiar with PWT, but haven't had luck specifying them before. The contractors usually freak out. It's "common sense" that you can't treat an LVL, after all. Do you know how they compare in cost to treated glulams?

84 Lumber? Good to know. 84 isn't popular down here; most contractors in our area (at least that I work with) use a regional supplier, Kempsville Lumber. With a couple of rare exceptions, I've only seen 84 used north of the James. They have a location not too far away, but they haven't managed to win too much business.

Might I ask, in what part of Virginia are you?

 

[80PercentTruth]

@phamENG

Glulam is definitely more expensive as compared to LVL. I'm in the Virginia Beach / Chesapeake area -- Kempsville Building Materials is a major player in these parts as you mentioned for all wood materials. I've worked with AJ and his team over there a few times with the development EWP for a few projects. Where do you practice? We structurals have to stick together to keep the architects in line and protect our fees.

"Engineers only know about 80% of the truth, the next 10% is very difficult to achieve, and the last 10% impossible. If we are bound to be wrong, we may as well be wrong simply and conservatively."

 

[phamENG]

Nice. We're neighbors! I'm in southern Chesapeake and work from OBX to the Northern Neck and Virginia Beach to Roanoke, a handful of out of state jobs (but not many), but most of my work is here at home. Are you an independent or work for one of the firms in the area?

There are two other members from nearby - one (though he's not as active anymore) is in Williamsburg, and another in Richmond.

And thanks for the insight on the treated LVL - since there's only one show in, well, the country making them I wasn't sure how high the premium on them would be. Good to know they're more affordable than Glulams - I'll make the switch on my next job.