Plumber drilled through exterior 2x4s - that's bad, right?

Question

I'm doing a bathroom remodel and adding a utility sink for my wife's art studio on the floor above. When we talked over the plan, I decided to go with the 2" drain they said I should use, but I had wanted to send it through an interior wall. However, they talked me into the exterior wall and said they would connect to the tub drain right where it came down. I even installed a ledger ahead of time and we talked about drilling through it for the drain.

Somewhere along the line though, the plumber changed his mind and went through 2 structural 2x4s. I was shocked when I saw it. There's less than an inch of wood on either side of the hole.

What should I do? Doesn't this weaken the wall? It even blocks me from installing the other ledger I'd planned and one of the joists it goes between has a huge gouge out of it I'd planned to deal with.

Here are some pictures:

I thought I would add an earlier picture of the joist I was going to shore up. It's a little hard to see due to the shadow, but there's a horizontal chunk of wood that is missing just above the sister. My plan, before the pipe was unexpectedly routed there, was to add a ledger on either side. That joist was notched way too wide before I bought the house. Now with the pipe in the way, I'm not sure how to address this.

More pics - Adding a few more pieces for better visualization of the off-center stud hole:

Update: I just spoke with the building guy at the township construction and code enforcement office. He pointed out that given the shape of my roof, it is a loadbearing wall. I forget the name of the roof type, but it's essentially almost like a pyramid (with a wide peak). I thought this was a significant detail I should add.

Answer 1

Since your house is the vintage it is

Old houses, like yours, that predate modern lumber dimensioning often can't use stud shoes, as you discovered. Since you're in that boat, you can try nailing a 8-10" piece of 2x blocking that's been notched to go around the pipe to the studs in question (this was what was done to reinforce the studs that were notched for the kitchen sink drainline in the 1950s ranch I live in).

For folks with modern studs...

This sort of problem is precisely why stud shoes are a thing. These are sheet-metal pieces that fit over the pipe-in-stud-hole and are nailed or screwed into the stud to reinforce the weak spot the hole created. I'd use Simpson HSS2-SDS1.5s (shown below) for this job; they're a bit trickier to install as you have to bend part of them around behind the pipe, but they're capable of transmitting both tension and compression around the hole, something regular stud shoes aren't rated for. (They also come with all the screws you need to install them.)

P.S. If the shoe doesn't quite fit because the hole's too far forward, you should be able to use a shim between the front of the stud and the front of the shoe. The results won't be great, but they'll be better than what you have...

Answer 2

There's really nothing to worry about here.

1. Yeah, the holes should've really been centered. A stud with even 3/4" of wood on each side retains much of its original stiffness, and the strength lost for just two studs is not significant. A stud with what's effectively a large notch loses a lot of stiffness. However, it's not a concern for just two studs in a wall system like this.

2. You don't need to repair this with hardware. There's a huge amount of strength in that wall system. Solid wood sheathing spans all those studs and ties them together. Nothing is going to fall apart. It's been done just like this for a century.