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Question DetailsAsked on 2/5/2018

Can vertical stack in house sewer line be relined?

Straight vertical line of cracked pipe basement to roof--4 inch. Don't want to tear out walls. Want to line inside of pipe instead

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1 Answer


Depends but almost universally I would say not a good idea (with relining schemes) or no with sleeving a new pipe into it. Minimum vent pipe size is 1-1/2 or half the vented line diameter - so assuming it is coming off a 4 inch DWV stack, a 2 inch vent pipe would fit inside and work in theory. However, when you think about it, unless this is a vent only from the bottom of the stack where you could tie into it there (done in some houses as part of the overall venting system, to vent main sewer gases directly to the outside bove the roof), you have no way to seal and connect it at each vent connection to the vent stack - so relining it is probably not viable because you would have to access each vent connection point to remake the connection. See typical venting diagram below showing the many connections commonly made to a central vent line - and not all houses have central vents.

Replacing the pipe from above is out because allthe connections - which normally are wyes or tees in the stck itself, so you would never have clearance to pull them out.

I suppose you could find (for probably $1000 range or more) a sewer line relining contractor who will claim (rightly or wrongly) that they can reline it with an epoxy or resin liner - don't know if that is legal in stacks or not, and I would not count on it working right.

I would get a sewer camera run for probably about $100-150 (with a video copy for you to keep to show to any relining contractor) down it to count and locate (with distance measurements) the vent connections to that line to see where and how much of a problem replacing the existing line would be. Then look at where to go from there.

Note you said "tear out walls" - in most cases, about a 16x24" hole would be enough to do this connection work to put in a new vent stack, so you are probably not talking (assuming the tributary vents are not cracked too) more than maybe 3-4 openings.

Now - the bad news. If you have a 4" vent, I would give at least even odds you have a central combined stack-vent there - that the "vent" you see is actually the sewer stack with a vent continuation to the roof, so in that case I certainly would not trust any sort of relining job over a cracked pipe to stay totally watertight. These methods (spray linings and inflatable resin-impreganted linings) are made for in-ground sewers where a touch of leakage willnot be noticed or a problem.

If you shine a BRIGHT flashlight (like many LED one) down from the top and then have someone run water and flush toilets and such, you would quickly see if that is the case or not. Here is an image of what your house plumbing likely looks like, assuming it hs one central vent rather than one from each bathroom or fixture:

I would say you are best off just biting the bullet, locating the connections and putting in the minimum size access holes (maybe using 1/2-3/4" diameter access holes for a fiber optic scope or camera first to optimize the access cutout location for minimum size), cutting allthe connections, pulling the stck through the roof (bear in mind it may have fire flashing connected at each floor), then put in new connections - slipping new straight lengths down from above between each connection.

Answered 2 years ago by LCD

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