Cutout of joist for toilet drain

[Nathan W. Swilling]

Here are some pictures of the beef up.

[mnahrgang]

Nathan,
That doesn't look "engineered" to me. It looks like a patch. Was that designed by an engineer, or architect?

I'm finding it a little hard to believe that that little bit of plywood is going to make a huge difference. Those metal plates appear to be simply shields to keep from nailing into the pipes, and not structural.

[jkogel]

Originally Posted by mnahrgang

Nathan,
That doesn't look "engineered" to me. It looks like a patch. Was that designed by an engineer, or architect?

I'm finding it a little hard to believe that that little bit of plywood is going to make a huge difference. Those metal plates appear to be simply shields to keep from nailing into the pipes, and not structural.

Agreed. The plywood should at least be continous under the pipe, where the wood of the joist is thin and in tension, prone to snapping. Next time, cut more pipe and less wood.
Run the pipe parallel to the joists over to a supporting wall, then drill if you must.

John Kogel
www.allsafehome.ca

[Richard A. Hetzel]

From what I see, through the eyes of an architect, those joists will fail, and the "beef-up" isn't nearly beefy enough. The joists will still fail. Isn't this the same guy who wanted to "hinge" his roof, earlier? And didn't we advise him then, several of us, that he needed professional advice? This is one reason why that was true. Whatever he saved in professional fees then, he will now spend the same amount or more trying to correct this atrocity. If the plumbing must be perpendicular tio the joists, it must be run either over or under them. The joists cannot be weakened by such huge holes. They will fail, perhaps catastrohically. There is no "beef-up" that will prevent the failure.

Whoever suggested a post to the rafters ought not give structural advice. What on earth will that solve?

[Nathan W. Swilling]

FYI, I hired a structural engineer to design the framing for the dormer.

This work is being done by a general contractor, and I'm just checking on his work to make sure it's sound.

[Nathan W. Swilling]

Do you think the building inspector will fail it? If so, there's no problem - as the GC will have to fix it. If it passes inspection, then it's me just arguing with the GC.

What would be the remedy now? Those plywood "supports" are glued to the joists, so they aren't coming off. Maybe put another layer of plywood (this time continuous around the hole) and glue/screw that to the existing joist/plywood?

[Larry D. Kage]

Originally Posted by Nathan W. Swilling

Do you think the building inspector will fail it? If so, there's no problem - as the GC will have to fix it. If it passes inspection, then it's me just arguing with the GC.

What would be the remedy now? Those plywood "supports" are glued to the joists, so they aren't coming off. Maybe put another layer of plywood (this time continuous around the hole) and glue/screw that to the existing joist/plywood?

The building inspector may pass it as they often miss seeing items of importance. Passing the inspection is not an indication that something was done correctly.

The remedy is the same as before. For your peace of mind and the structural integrity of the floor framing, have it designed properly by a qualified professional...or don't. It's is up to you.

[Nathan W. Swilling]

Or, if it's difficult to have the plywood continuous around the hole, maybe notching another piece the other way, and sliding it under? Sort of like a U and an upside down U overlaid on top of each other.

[Michael Larson]

Originally Posted by Nathan W. Swilling

Or, if it's difficult to have the plywood continuous around the hole, maybe notching another piece the other way, and sliding it under? Sort of like a U and an upside down U overlaid on top of each other.

Nathan, please pay attention. You have been given good advice here and that is to contact a design professional. Get er done.

[Frank P. Newman]

Originally Posted by Nathan W. Swilling

Do you think the building inspector will fail it? If so, there's no problem - as the GC will have to fix it. If it passes inspection, then it's me just arguing with the GC.

What would be the remedy now? Those plywood "supports" are glued to the joists, so they aren't coming off. Maybe put another layer of plywood (this time continuous around the hole) and glue/screw that to the existing joist/plywood?

The problem is that the weakened area over and below the pipe penetrations will be helped very little by the plywood on either side of the opening, even if the plywood extends many feet along the joist. I'm not attempting to offer a design here, but the best engineered solution will likely be metal plates on one or both sides of the joists that will likely require pipe removal (easy) for installation.

[Jack L. Gilleland]

Oh BTW, the plumbing inspector shouldn't pass it either.

[ldapkus]

I recommend Crazy Glue or a sky hook.

[Richard A. Hetzel]

FYI, I hired a structural engineer to design the framing for the dormer.

Sorry, no medal. A structural engineer will see only his part of the work, while an architect has a full overview of the entire project, including the structure.

Maybe those joists would have a prayer of holding if significant steel bracing were applied to them, and by that I mean hot-rolled steel angles as big as the pipe will allow, on all four corners of the joists, extending from support to support. Anything less than that is wishful thinking. The angles will have to be engineered before any installation is attempted.

Failing that, the only cure would be to remove the piping, sister the joists with new joists of the same size extending from support to support, and reroute the piping below the joists, or redesign the layout so that the piping runs parallel to the joists. Both the plumber and the general contractor should have known better than to try such a stunt. No matter how much plywood you stick on the sides, it ain't gonna help.

[rmaday]

Do the same rules apply if there is no span?

[Richard A. Hetzel]

What is meant by "if there is no span"? A joist by definition is a structural member which spans a distance. If it's a joist, it has a span.