1 + 1/2 baths worth of waste plumbing ?'s

[stayalert]

I've decided to tackle a project that has been inching its way up my to do list.

I intend to replace waste plumbing (at least the drains possibly not the vents) that is currently constructed of cast iron...with pvc.

a) existing plumbing is rotting - visible seepage on bottom of straight sections and elbows.

b) existing plumbing is accessable via a crawl space (2-3 feet from earth to framing/floor)

c) exsiting cast iron connected to septic sytem that is maintained, updated and suitable for fixtures attached to it.

d) another protion of the house was renovated previously - at that time waste plumbing was replaced with pvc and the septic sytem renovated

e) this is a repair not a renovation

so???

any tips?

1) what are the changes in elevations for various size waste pipes?

2) I hope to support and re-use existing cast iron stack/vent - concerns?

3) I'm not a plumber but have sniffed a little pvc cleaner and cement during other assorted home repairs...

4) the exisitng cast iron served us well but the ease of working with plastic is a plus. The environment is coastal Massachusetts and the salt air/humidity has taken its toll on the iron.

5) Does anyone want some well used/aged vinatge cast iron pipe? I'll sell it cheap....

I tried twice to hire a plumber that we have a good working relationship with. He has winterized and "summarized" this home for many years and I hope he will continue to be a resource in that regard. I have twice requested an estimate for him to take on this project but he has been unresponsive (I think the seasonal shuts and start ups are his thing and I thik he doesn't like spiders or something - re: crawlspace) Anyhow - bring on the free advice

 

[Toyo FJ40]

Well 1/4 per ft is standard slope for drainage but you can go as light a 1/8 per ft on 4" and 3"

Watch when cutting the main vent stack, it can have a lot of weight standing on it.
Does your fixture each have a vent or maybe back vent to the main stack? If they do you can cut them above the fixture and furnco couple to them.
If you have a decent roof flange you might be better off sliding a new PVC vent out through the roof.

Iron is good for anywhere from 30 to 50 years depending on the weight (thickness)


Kevin

 

[stayalert]

Thanks Kevin,

Good tip on the stack weight, my bro. in law (a plumber in CO) also cautioned me about that.

I intend to access the vent and support it as neccessary before taking its legs out from under it so to speak....I'll have to revisit the roof penetration. I'm sort of assembling thoughts and plans for this project that I hope to start (and finish) next week. I recall my bro in law saying 1/8 per foot for the larer diam (4or 6 I can't remember) pipe. at first glance it loooks like I have good clearance and room for adeqaute slope. I want to support the run down stream of the fistures properly though as it is roughly 30 - 40 feet of pipe from the furthest fixture to the septic access......