I want to replace the drain pipes for my kitchen sink and washing machine...i currently have a 35 year old house with 1 1/2 inch black iron and galvanized drain pipes...i can access the drain from the washing machine easily by removing a section of paneling...the kitchen sink is not easily accessible due to the kitchen cabinets... i had one plumber come out to quote me a price on replacing the orangeburg main sewer line, and i asked him about the drains...he said he would use 2 inch schedule 40 pvc drain pipe from the sink and the washing machine...he really felt it needed 2 inch pipe...he would simply cut through the bottom of the kitchen cabinet and run the pipe straight through the floor...he would attach a vent under the kitchen sink...on the washing machine, he would use fernco coupler to attach pvc to the existing vent... my questions are: 1...is 2 inch pipe the best or is it too big??? 2...is the undersink vent work well??? 3...is it ok to use 1 1/2 pipe from the drains and attach that to two inch under the house??? 4...what do i do with the old vent??? is there a cap or something to keep rain from coming down into the crawlspace through the pipe??? 5...what is the best way to attach the pvc to the main trunk under the house??? where should i cut the old 1 1/2 inch pipe off the trunk and attach the new pvc??? if you need any more information...please post back...thanks for your help...

I have a thermoplastic or fiberglass shower unit which was leaking at the brass/rubber gasket drain. I replaced the drain with a similar part; however, it is still leaking. I believe it is leaking between the rubber gasket and the PVC pipe. How can I verify which joint the leak is coming from? I've tightened the jam nuts as tight as I can get them. There must be some trick to getting the drain to seal. Should I have replaced part of the PVC pipe for a better sealing surface? Should I have used plumber's putty? Any help is greatly appreciated.