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Wood columns bearing on concrete

Wood columns bearing on concrete

Wood columns bearing on concrete

Hi all,

I have a residential remodel project where the contractor is refusing to install 6x6 oak columns with the knife plate detail we have specified. Right now the columns are bearing directly on concrete and are held into place with concrete screws. This connection is horrible in the first place, but the contractor is trying to argue that it is allowed by code. Here is his argument: "They (the columns) are in the living space many feet from exposed earth and there is a moisture barrier below the concrete that they rest on." Is anyone aware of a specific code reference (IRC) that does or does not allow this condition? We are not allowing the untreated wood to bear on concrete but I'm looking for ammunition for my argument.

Here's the code snippet:

R317.1.4 Wood Columns
Wood columns shall be approved wood of natural decay resistance or approved pressure-preservative-treated wood.


Columns exposed to the weather or in basements where supported by concrete piers or metal pedestals projecting 1 inch (25 mm) above a concrete floor or 6 inches (152 mm) above exposed earth and the earth is covered by an approved impervious moisture barrier.
Columns in enclosed crawl spaces or unexcavated areas located within the periphery of the building when supported by a concrete pier or metal pedestal at a height more than 8 inches (203 mm) from exposed earth and the earth is covered by an impervious moisture barrier.

RE: Wood columns bearing on concrete

It would seem that based on the exposure (or lack thereof), the contractor is most likely correct that the code would allow the wood to bear directly on the concrete. However, I'm a little confused as to how the contractor can refuse to do what you've specified, and presumably are paying for, him to do. Also, aren't there some requirements for lateral force capacity for that type of column connection?

Edit: My view that this would be allowed per the code assumes that the concrete is at least 6" thick where the post bears on it. Otherwise, it doesn't meet the requirements for an exception.

RE: Wood columns bearing on concrete

We have to provide an engineering letter stating that the construction meets our specifications so the contractor is not exactly in a position to refuse to do what we specify. The contractor was openly refusing to use the detail we specified so I'm looking for any code justifications to back up my decisions.

RE: Wood columns bearing on concrete

If the contractor has a contract to do what your documents say, the code doesn't matter. Codes are just minimum provisions, not necessarily best practice.

RE: Wood columns bearing on concrete

If I'm hearing you correctly, the contractor agreed to do the work per your specifications, and you specified the connection you wanted. If so, why do you need to justify what you specified per the code?

RE: Wood columns bearing on concrete

I gave the contractor at the site multiple reasons to do what we specified (and got into a heated argument):

1. What was constructed doesn't follow our plans
2. It is not best practice to have untreated lumber bearing on concrete
3. The architect requested and is expecting this detail
4. It is against code provisions

I clearly don't NEED to justify it per the code, I'm just looking for any bullet points to help out my argument. It's also nice to know the code provisions for when this happens again in the future.

RE: Wood columns bearing on concrete

Tell him to do what’s on the drawings! I would have no time for this level of nonsense from a contractor!

RE: Wood columns bearing on concrete

Sounds like your contractor may be like a pig in mud. He likes to argue. Just tell him who is giving the orders here.

RE: Wood columns bearing on concrete

How close is it to the end of that contractor's part of the project?

Sometimes I am tempted to add "bullet points" as well, but as others have pointed out, there only needs to be one.
- Not to drawing, fix it. (politely, with a sympathetic smile, with a little of the good cop/ bad cop spin )

I'm guessing The contractor probably has had similar "experiences" already. So probably also knows that The back-charges to correct the work will come out of the final payment.

RE: Wood columns bearing on concrete

First, I agree with all responses that say he needs to do it because you designed it that way. I would also prefer in these situations to be able to explain why I do something as a credibility point but I am confused as to what he is saying he is not going to do.

The section you cite only has to do with whether a wood column has to be decay resistance or treated, not how it is connected. If you meet any of those criteria, you can use the oak column I presume. Which criteria do you meet? Showing your detail would also help study your situation.

RE: Wood columns bearing on concrete

Here's a sketch of what is in place:

This is what we designed:

It's really frustrating for a contractor to blatantly ignore the drawings and to show up to an inspection to make-shift crap like this. I was really tempted to bail on the inspection as soon as the contractor refused to fix this since there was no point of me being there. I understand things don't always work out, so I try to work with contractors if they treat me with respect, are reasonable, and try to work out issues ahead of time. This was definitely not the case.

This project also has a HSS tube fully welded moment frame. Apparently the HSS beam came to the site with a wood LVL nailer bolted to one face. The welder didn't remove the LVL nailer and only welded one side of the beam to the column. Pure laziness. Now there is a floor structure attached to the steel frame which is going to make any repairs very difficult. This framing inspection was a big time fail.

RE: Wood columns bearing on concrete

The in place detail youre showing has to be a joke, right?
"install per contract docs". Thats all i'd say. I've been seeing a bunch of piss-poor work as of late. Especially welding, which is slightly concerning.

"The welder 'fabricated' the knife plate out of 'scrap metal' that was on site." - Mr. Inspector Man. We will definitely not approve a braced frame connection that was fabricobbled together like that...

RE: Wood columns bearing on concrete

Here is good one I got from a contractor. My response to RFI: Install CMU lintel at doorway per detail XX. Contractor's frantic email: We cannot purchase a lintel with rebar extending out of the end. *palm to face* Ummm the rebar is placed in the field then you grout the wall...

RE: Wood columns bearing on concrete

Here's a picture of the column in place directly on concrete and secured with nails (the contractor claims there is a 5/8" bolt installed now):

At the same project, here's a picture of a deck beam bearing on a single untreated 2x4 which is also split in half:

RE: Wood columns bearing on concrete

Wow - and I thought the quality on Irish sites was bad!

How does the client feel about his rogue contractor?!

RE: Wood columns bearing on concrete

There are honest mistakes, and there is incompetence. You appear to be dealing with gross incompetence. I would not entertain any arguments from this contractor. I see no reason why he cannot install the connection you designed and specified using post-installed concrete anchors. The deck beam is just icing on the cake of cluelessness.

If you want to have some fun pulling his chain, tell him that his non-conforming bearing connection at the base of the column has introduced an eccentricity that results in a reduction in column capacity.

RE: Wood columns bearing on concrete

If you want another bullet point to add to the overkill of reasons the installed connection is unacceptable, the end bearing area looks to be only about half of the column cross section area, which presumably reduces the axial capacity by about half.

RE: Wood columns bearing on concrete

So he whittled out a notch in the bottom of the column and ran a single tapcon through the wood to the side of the slab? Now the untreated column is just sitting in a hole in a slab? First, fix the hole, then install the knifeplate. After that he can go wreak havoc on his next project if he wants.

Don't let him B.S. you with code requirements and all of that. Call him out on his pitiful work, without being too rude. I 100% guarantee he knows this is trash and it should be fixed. He's just seeing if you'll let it slide.

Not to mention the welding issue... And the 2x under the deck... Who hired this guy? Is there no inspector involved (third party/building official)?

RE: Wood columns bearing on concrete

I'm getting nervous thinking the examples mentioned so far may be just the "tip of the iceberg."

The stuff that does not show is particularly unsettling.

RE: Wood columns bearing on concrete

His crappy detail does not meet R317.1.4 It says must be on a concrete "pier" or metal plate 1" above the floor. He is not above the floor. Also, the code does not specify the actual connection to the floor, that is your job. The exposed earth portions is not applicable at all.

His construction is poor in several respects.

RE: Wood columns bearing on concrete

If you can a discussion with Home Owner may also be needed the contractor has been in their ear all project at this point and they will surely be singing a tale of delay and more cost to the owner to make the proper corrections and the home owner usually doesn't know any better that they should not be responsible for the cost. Sadly run into this a lot with residential construction.

Open Source Structural Applications: https://github.com/buddyd16/Structural-Engineering

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