Plumbing Stub-Ups in Foundation Grade Beams

[Christopher C]

Hello Everyone,
I generate designs for some residential projects in Austin, TX, and occasionally perform pre-pour inspections for some foundations. I've run into something with a new contractor that I'm having a hard time finding more resources on, and I thought some folks here might be able to help.

A few of the plumbing stub-ups in the recent foundation that I inspected were coming up through the grade beams, and others were positioned flush with the outside face of the exterior grade beams(examples attached). This was clearly affecting the integrity of those beams, so I failed the inspection and asked the plumber to re-route his lines.

My client(a pretty reasonable one) called me later to ask about that request, and we had some conversations with other builders who have never had a problem getting those conditions passed here in Austin. I though maybe the rocky soils that support most of Austin might cause inspectors and other engineers to relax their requirements, but I still see these conditions as unacceptable. I would like to explain this to my client in a way that's understandable to a non'engineer(i.e. no text books of white papers). I thought I could find some sites that talk about this, and maybe show my client some photos of failures caused by improper pipe placement. My search is coming up short... Do you guys know of any?... Am I over thinking this?

Thanks in advance.

https://files.engineering.com/getfi...2-4d8a-a50d-085f8d531ca2&file=0129191433a.jpg

https://files.engineering.com/getfi...ca-925a-e7daf58c5023&file=0129191430g_HDR.jpg

“When engineers and quantity surveyors discuss aesthetics and architects study what cranes do we are on the right road.” ? Ove Arup

 

[Agent666]

I'd say for the ones hard against the formwork and the reinforcing that it's a matter of durability, no cover locally may or may not be an issue long term (depends on the environment) . You'll find lots of pictures of corrosion of reinforcement with minimal concrete cover, perhaps not caused by a pipe, but it's the same mechanism/action.

For the one in the middle of the beam, if it has sufficient cover to all reinforcement and the beam calc works out with the loss of width I'd tend to say that's actually ok. But I would have the same concerns as you about the pipes right on the edge of the beam.

 

[GC_Hopi]

Its hard to tell whats going on from the photos since the pipes are covered in the vapor barrier and it all looks the same but check ACI 318 Chapter 6.3 It gives limits/guidance on embedments, e.g. conduits pipes, and sleeves, in concrete.