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in the renovated bathroom that I’m building. I need to go as small as possible, because I have to go through joists for quite a ways to reach the location. With the 1/4″ per foot slope, I’m going to start running out of the part of the joist where it’s safe to drill through. I’ve asked my local plumbing inspector if I could go with 1 1/2″: he mumbled and grumbled and said yes, he thought so. That didn’t sound very definitive for me.
I know that I have somewhere the unit drain values for showers and sinks, but darned if i can find them when I need them. Can someone point me to a site that has them?
Replies
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Check:
http://www.codecheck.com/plumcode.htm
*I believe that a shower requires a 2" drain and trap.You can use 1/8" slope on pipe under 3".
*2" for the shower is correct but where do you get the 1/8" slope idea fom. I never heard of it. In fact I think it is wrong. If you can prove your case based on any national codes please correct me. If it is only a local code you should specify that.
*Believe the national codes say the minimum slope should be 1/4" per foot. Can use 1/8" per foot if 4" pipe or with 3" pipe up to 36 fixture units. Can also use 1/8" "if approved by local authority." I believe the max slope is 1/2" per foot and if want to exceed that, is best to go to 45 or 90 degree drop, then back to your horizontal pipe.Diameter of pipe, as you know, depends on fixture units. Seems the national codes agree that shower is 2 FU and lavis 1 FU. Total 3 FU. Is disagreement as to what size pipe handles how many units. One national code says 1-1/2" diam. will handle 3 FU. Other code says 1-1/2" will handle only 1 FU. They require 2" diam. for 3 fixture units. As someone said, best check with local to see what national code is in power. If inspector doesn't know, and you don't have code, then copy at municipal and at public library.I'd like to see other takes on this question. Some thoughts. Randy
*You are 100% right Randy. I didn't give the details because I wanted to see where this person was coming from. Personally, I think this was another case of bad advice from a DIYer who didn't know what they were talking about. Of course we all know THAT is a rare thing here! NOT. LOLNOTE: I did not say DIYers do not know what they are talking about. Some do. Some don't. This one didn't.
*Section 417.3 of the International Plumbing Code states waste outlets serving showers shall be at least 2". Table 704.1 shows pipes 2.5" or less shall have a min. slope of 1/4" per foot. Also you should know that the International Residential Code (section 502.8) states not to drill in center 2/10's of joist span, under bearing walls at ends or closer than 2" to top, bottom or sides. With a 2" pipe, notching is out of the question. You basically need a 2 x 10 joist to meet code when you drill for a 2" pipe. However, depending on the span, you may get away with something less if you double the joist or strenghten it with plywood. Of course you would have to ask your inspector what he/she could live with. The International Code was designed to be compatible with BOCA, SBCCI and ICBO. BUT being an inspector, I can tell you it's better to communicate to your inspector what you're planning to do before you do it, if you don't do this for a living. Enthusiastic homeowners that appreciate help actually make my day. Good luck!
*I only quote the 1&2 Family Dwelling Code here.I guess we all agree on the 2" drain for showers.On the 1/8" slope. My old code book gave 1/8-1/4" slope for all drains. The 1998 code book requires 1/4". Randy indicates 1/8" "if approved by local authority" I suspect that comes from the National Plumbing code. (I allow 1/8" on remodels.)I always cut first timers a lot of slack.
*OK, thanks for coming back. I take it back you do not know what you are talking about. My bad.I still think you were mixed up on the under 3" thing but whatever....
*Thanks everyone for your responses.Bob Chapman
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in the renovated bathroom that I'm building. I need to go as small as possible, because I have to go through joists for quite a ways to reach the location. With the 1/4" per foot slope, I'm going to start running out of the part of the joist where it's safe to drill through. I've asked my local plumbing inspector if I could go with 1 1/2": he mumbled and grumbled and said yes, he thought so. That didn't sound very definitive for me.
I know that I have somewhere the unit drain values for showers and sinks, but darned if i can find them when I need them. Can someone point me to a site that has them?