Securing a vent stack

I've run into a couple of situations now where I need to cut into a vertical stack to either replace a damaged connection or re-route the stack. In both cases, however, the stack runs too close to a stud to use a riser clamp near the repair junction. Is there another solution, or am I just exhibiting my natural ignorance in not being able to figure out how to make the riser clamp work? I suppose I could go all the way up and install the clamp on top of the ceiling joist (even removing the vent pipe to just below the joist, too, since it's all galvi and heavy as sin), but so many of the illustrations I've come across show the clamp braced in the wall that I was wondering if I was missing something.

Thanks in advance for any advice.

Jay

A friction clamp resting on the floor.

A piece of 7/8" or 1-5/8" unistrut and a strut clamp...
Screw the strut to the 2X4 then use the strut clamp to hold the pipe...

When you say a riser clamp won't fit, are you thinking long ear or short ear riser clamps?

kordts said:

A friction clamp resting on the floor.

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Or resting on a temporary 2x4 tacked in place between adjacent studs if you want to support it above the cut.

srdenny said:

When you say a riser clamp won't fit, are you thinking long ear or short ear riser clamps?

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Both. The pipes run right along the stud, so there is no room for a clamp. The same is true at floor level, of course, which is why I thought about going above the wall and grabbing it in the attic. I think I read that code says <15' to support a vertical run (this would be about 5' away), so I was using that as a guide. The unistrut looks like an interesting option, though in one case I know I couldn't get the support behind the pipe, let alone figure out how to attach it to the stud once it was there. Still, I'll keep it in mind for areas where there is zero side clearance but room for something in back.

Thanks to everyone for the help!

Jay

how about a two hole galvinized pipe strap bolted directly to the wall that the pipe is so close to?

poorplmbr said:

how about a two hole galvinized pipe strap bolted directly to the wall that the pipe is so close to?

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That's the problem with old construction. My walls are lathe and plaster; not exactly something you want to hang your plumbing from . Boring the adjacent stud might work, but there really isn't a lot of room behind it to work in a clamp, and I'm afraid I would bust the plaster if I tried. Clamping directly to the stud is even less attractive because any bolt holes (using a U-clamp or similar) would be very close to the edge. I guess if I put a strap across the U-bolt ends it wouldn't really matter, but it seems very "inelegant".

I have to say that I am certainly learning a lot from the whole process, and the crew here has been very helpful. Despite the several books I've bought, it's clear that there is a difference between the examples in the text and the "real world". My "reality" is that I'm going to have to install the clamp in the attic; and from what I've seen so far, I suspect that stacks run too close to studs for clamps in a lot of cases. Supporting them is just one challenge; for me, cutting them without damaging the wall behind or the stud is even tougher.

Those who do this for a living have earned a fair amount of respect from me, too. Working with pipe while lying on your back in the dirt with only 2 feet of clearance can't be fun (especially when you discover the cat has been using the crawl space as a litterbox for the last two years ). At least it's one aspect of this project I'm not looking forward too...

Jay

jay_sfb said:

Those who do this for a living have earned a fair amount of respect from me, too. Working with pipe while lying on your back in the dirt with only 2 feet of clearance can't be fun (especially when you discover the cat has been using the crawl space as a litterbox for the last two years ). At least it's one aspect of this project I'm not looking forward too...

Jay

Click to expand...

Welcome to the life of a plumber!
Now thats glamor!

GrumpyPlumber said:

OR, best idea yet...YOUR idea, clamp it above in the attic.

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Its an old thread - but this post helps to verify what I have to do next week - but I think I'm also going to cut into the wall behind the vanity in the bathroom and get another clamp setup there in addition to one in the attic (which will be supported on extra 2"x6" pieces attached to the joists). I have to remove most of the old CI in the basement and I know darn well that the stack is not supported well. Its using the old school thought of build it from the bottom up and uses some perforated galvanized straps to help hold it up. Its a wonder the thing hasn't crashed.

Looking forward to this lovely job...

pipe

1. Wrap perforated metal plumber's tape around it and screw it to the stud.
2. In most cases there are branch lines off the vertical stack that are going to support the stack anyway. I have seldom had to add independent support unless the stack is a straight section without branches coming into it.