wooden supports instead of metal strut

[malachi constant]

I am the engineer on a K-12 project where a contractor is performing work above an existing ceiling. The construction is CMU walls, EMT conduit, and ACT ceiling. The contractor has brought to our attention that much of the existing conduit above the ceiling, where it is attached the wall, is in fact attached to wooden 1x4s that are attached to the wall. The 1x4s are screwed into the wall, with standard EMT straps securing the conduit to the wood.

I am investigating whether the ceiling is plenum. Assuming it is not, does electrical code prohibit this? NEC 358.30 (securing and supporting EMT) does not address this, neither does 300.18 which it references.

Also, I can see in the photos that not all conduit is secured within 3' of junction boxes. Sometimes one conduit is properly secured, with other conduits just tie wrapped to each other. (But not even tie wrapped to the secured conduit LOL.) My guess is that is the kind of thing the inspector can decide if he wants to enforce cleaning up, but it is out of the scope of this project. Ditto the wood.

Thoughts on the woods supports, assuming it is a non-plenum space?

 

[hbiss]

I'm not seeing anything wrong with. Are these walls exterior and perhaps the 1x is to space the conduit off of the concrete because of moisture?

Further, since this is existing and not within the scope of your contract, I would leave it or pursue a change order to correct it if it is decided that it needs to be corrected.

-Hal

 

[hillbilly1]

I would only see a problem if it is fire rated.

 

[malachi constant]

Looks like it is a plenum space, and we found the building code that prohibits noncombustibles (ICC/IMC 2012 602.2.1). I'm not the engineer of record (for neither the old or new project) so will pass this info onto the team and let them collectively decide how to move forward. I assume they'll loop the inspector in and do what he requests, and assume it will be relatively painless for the Owner to fit it in their budget. Thanks all!

 

[hillbilly1]

You mean combustibles ? LOL! I have seen plenum’s built out of structural wood framing before in houses. They would just box the open side of the floor joists with Sheetrock, and seal the cracks with duct seal.

 

[tom baker]

That was common in the past. Dont think ig is allowed under energy codes

 

[hbiss]

I've seen water heaters sitting on a suspended plywood platform in return air spaces. You can install transformers in that space too.

-Hal

 

[Dennis Alwon]

Yes wood is allowed but it must be fire rated, IMO

 

[jap]

They may have used he 1x so they wouldn't have to use individual plastic anchors for the straps.

Using wood screws for the straps and only 2 or 3 anchors to anchor the 1x to the block.

Actually a pretty smart idea if allowed in that space.

JAP>

 

[sameguy]

Also, "painless" you might want to check out the price of strut, fasteners, removal, labor, sounds like big money to me.