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runner041 01-10-2011 07:55 AM

replacing cast iron drain pipe
I just bought an old early 1950's home for my daughter and grandson. We are in process of doing a remodel. Some of the cast iron drain pipe is leaking. Rather than just replace the section that has the leak, I would like to just replace all of the pipe to PVC. It's a very small home and would be pretty inexpensive to replace it. That way I'm assured that we won't spring more leaks later.

My problem is that the main vent is a 4" pipe going through a wall and then the roof. I would rather not replace this section. I can get a sawsall on this pipe to cut it free and just use a rubber boot coupler to tie to the new PVC but I'm afraid the pip might want to come down if I cut it loose. It's got to weigh a ton.

Does anyone have any suggestions to keep it from coming down when I cut it loose? I was thinking of using a couple of pipe straps wrapped around the pipe and tied to the joist in the basement to keep it in place long enough to get the new fittings attached and a new strap or two to hold it there after.

There is no water draining into this vent. It is the main vent only.


kok328 01-10-2011 03:53 PM

Yep, attach some pipe hangers and secure it to the floor joists. I would leave this rigging in place afterwards as PVC won't support the weight and will be prone to crack.

runner041 01-11-2011 04:49 AM

Good Idea to leave the straps in place!

joecaption 01-11-2011 04:44 PM

What you need is a riser clamp in the attic sitting on blocking to stop it from dropping. I'd bet there's alreay one in there some place on the line behind the wall or in the ceiling area.

The one in the picture is far more heavy duty then you will need, just an example of what one looks like. Any real plumbing supply or sprinkler company will have them/

runner041 01-12-2011 04:47 AM

Nice! That will do the jobe very nicely!
Thank you very much!

mzzbunny65 12-30-2012 11:18 AM

After replacing all galvenized and cast iron pipes a drainage pipe for kitchen (now replaced) was removed-shortly afterwards where it was cut off at base the concrete around it collapsed and we now find the hole looks like it has "sludge in it-we are wondering......should we fill it with insulation then cap in come way.....Concrete? we are stumped no overflow, no leaks, just a hole about 4 in. across and 4 in. deep. Thanks for any help, Bunny

Wuzzat? 12-30-2012 02:12 PM


Originally Posted by runner041 (Post 52956)
It's got to weigh a ton.

Seven to twelve lbs/ft.

nealtw 12-31-2012 11:29 AM

Bunny ; Clean it out as best you can and watch it, If it fills again you may have a bigger problem. You could have sewer backing up or it could be the level of the ground water and may indicate the perimeter drain is not working as good as it should.

mzzbunny65 01-13-2013 04:04 PM

To nealtw~cleanened out all the Gunk-found old clay pipe, hole never got anymore water so filled with peagravel for now, not wanting to seal totally in case of future problems! Thanks for your help! mzzbunny65

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