I have a 4" cast iron pipe that runs from basement all the way out roof want to connect pvc into for washer waste using ferncoe rubber boot is that strong enough to hold that much weight

Hi bullfloat and welcome, the CI will need to be properly supported above the connection. Hang tight for an experts opinion, should be one along shortly.

Hi Bf

It isn't a great idea to insert a PVC fitting into a cast iron stack... weight of the cast iron stack above the fitting could crush the pvc fitting and allow the cast iron to come crashing down... ;)

A better job would be to purchase a 4"x2" NO-HUB cast iron wye fitting and install that into the stack using two 4-band husky clamps (see small picture of 4-band clamp below). These parts are available at all plumbing supply stores.

You'll also want to pick up a couple RISER CLAMPS so you can support the cast iron stack properly while cutting into and removing the cast iron section of pipe (see images below).

After you install the cast iron wye you can transition over to 2" PVC using a 2" cast iron x 2" PVC shielded transition clamp (picture of 3 clamps below)... not a rubber fernco.

Check out this link to another question like yours:

https://www.askmehelpdesk.com/plumbing/tie-sewer-line-underground-473616.html

Finally, you'll also need to vent the new washing machine drain line with an 1.5" vent... can connect back into another vent nearby. You could also install a mechanical vent (called an AAV) if they are legal in your area.

Good luck!

Mark

Hi bullfloat and welcome to The Plumbing Page at AskMeHelpDesk.com
You ask,
Will a ferncoe rubber boot strong enough to hold that much weight And the answer is NO! Use a Fernco Metal Shielded Coupling,(see image),
But hold on! How do you plan on supporting all that weight when making your cut? You use two 2 X 4s and a raiser clamp, (see images).
Here's how to do it, Take a 4 X 2" Sanitary Tee and prime and glue in a 6" piece of 4" PVC In the hub end. Get two Fernco Metal Shielded Couplings at the same time. Measure the overall length of the tee and add 1/4". That will be your cut using a set of ratchet cutters.
Cut the 2 X 4s a few feet higher then your cut and install the raiser clamp. You may now make your cut and insert the tee..
Before you connect the "P" trap and 36" stand pipe you will have ton lay another 2 X 1 1/2" tee on its back to run a vent off from. This vent can be run to the attic and revented back into a existing roof vent using a inverted tee. More questions? I'm as close as an click. You now have two solutions to work with. Good luck, Tom
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