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Retrofit pipe penetration in concrete wall

Retrofit pipe penetration in concrete wall

Retrofit pipe penetration in concrete wall

An MEP we work with asked for advice on a pipe penetration they want to install as part of an upgrade in an existing building (ca. 1986). Need to put a 12" pipe with 1" insulation (so...14" dia penetration) through a 14" thick concrete wall at 1st story of 3 story building. I have only partial building drawings -- from those, I believe the reinforcement is in one layer, #6@ 12" horiz. and #7@10" vertical. Penetration is to be located a few feet above existing door opening at grade. We don't have details showing exact conditions around door.

I've never had to retrofit a penetration that would interrupt reinforcement in an existing wall; anyone have experience and can advise what the simplest/most cost-effective course of action might be?


RE: Retrofit pipe penetration in concrete wall

It's very unlikely that the wall is designed to the gnat's buttocks such that interupting a couple of bars at 8 or so feet above the floor is a problem. Plus the fact that its above a door means that the gravity loads are already considered to flow on either side of the door. You could run shear, compression and bending calculations, but my feeling is it's OK by judgement. Some of my more rigorous colleagues might disagree. If you did the calculations, it's very likely that they've never been done before for the building. Concrete wall calculations are pretty trivial. 14 inches of concrete can carry a lot.

RE: Retrofit pipe penetration in concrete wall

Appreciate the response. I was thinking that we might be OK, but the "boss-man" is pretty conservative, so we'll see if I have to go through some sort of analysis. Seems like that would be a whole lot of work to go through...

RE: Retrofit pipe penetration in concrete wall

Not many 3 storey buildings would have a 14" concrete wall. Jed is right...just do it.

RE: Retrofit pipe penetration in concrete wall

14" of pipe and insulation probably means a 15 or 16" cored hole. Think of this as a well supported (confined) arch over its top half, a pretty stable structure or opening. If they could locate the horiz. rebar, and adjust the hole location a bit to avoid cutting a horiz. bar right near the top of the arch, so much the better. There is probably a little extra horiz. rebar over the head of the door, avoid that too. You would prefer that the hole be about centered over the door, rather than over one door jamb, where there might be some concentrated vert. rebars. Give a little thought to any concentrated loads right over the hole and door, and then the distance up to the second floor framing where there will likely be some beam reinforcing to bridge over your hole.

RE: Retrofit pipe penetration in concrete wall

At 14" thick, is this a bank vault? Are you trying to ...

The reinforcing pattern says otherwise though. So, ...no...

Mike McCann
MMC Engineering

RE: Retrofit pipe penetration in concrete wall

i would core cut a 15" -16" hole and insert a mild steel pipe that should be more than sufficient

RE: Retrofit pipe penetration in concrete wall

We are doing some renovations ourselves with penetrations and a good bet to make sure you hit as few bars as possible is to use GPR. The ground penetrating radar will easily show up all the steel in the wall. It would take only a few minutes if you know a local company that can do it and could give you some ease of mind and help to set up the location of the core.

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