OldSalt
Member
I'm building a house in Northern Idaho, and without getting into all the details, it's been a rough build. Budget is largely exhausted and I had problems with my original plumber, hence I'm completing trim and finishes on my own.
A professional plumber completed rough in, and passed inspection. However, when the vanities came in, the drain lines were positioned too low on the wall. I would have had to cut the bottom of the vanities in half to put the P-trap down low enough to meet the drain line. So I've made modifications, and am in the process of installing the finish plumbing and drains for the Master. I believe that I've messed up, and want to verify this before pulling out vanities, messing with granite, and ripping out walls (again!!).
I first realized the problem when the granite company arrived to set the counter tops. The vanities are "stand alone" and were not set when they arrived. The granite guy is an outstanding contractor, and attempted to help me by setting the first two vanities. He cut the base of the vanity to meet the drain height, and we agreed that he should stop there and let me finish plumbing and vanity install. It just wasn't working out.
This is what I worked out. (Get ready for some "plumbing".)
I realized when researching the Master vanity drain install that the Weir is not supposed to be higher than the vent. The vent is at the level of the top of the Sani-tee, which is lower than the P-trap weir. Thus this will be a "fail" at inspection (i.e. water could siphon out of the P-trap, because there's no vent break). I'm pretty sure that I need to tear this whole thing out, raise the sani-tee up six inches or so, and re-install with a straight pipe out of the p-trap angles slightly down to the sani-tee. Can someone confirm this, or offer a better option?
Second, similar issue. As illustrated in this rough (emphasis, ROUGH) drawing, the original installation had the double vanity drains split at the vent/drain intersection, with an elbow at either end (and a straight pipe stub from the elbow out the wall). To raise the drain lines height to meet the required vanity height, I opened the wall and added two elbows at either end of the drain line, one pointed upward, an approximately six inch pipe, and one at the top of the pipe pointing out of the wall. The problem is that the weir is now also six inches above the vent pipe.
Second, I apparently can't use a measuring tape, because the drains are too high. As illustrated in the picture below, the straight pipe from the P-trap back to the wall is angled up about 1/4", rather than down. Again, while I want my home plumbed correctly, a larger part of this is the final plumbing inspection. This is angle is slight enough that an inspector might not notice unless he puts a level on the pipe. And to be honest, having 1/4" water retention in the pipe just makes the p-trap an extra six inches or so long. The over riding issue is the design of the drain/vent/weir. Even if the inspector pass this, I'd know it's wrong behind the wall. Then again, how big an issue is this from a practical perspective. There are two vanity drains connected to the same 2" drain pipe.
1) What's the likelihood of a siphon being created that pulls the water out of either vanity drain p-trap?
2) What's the likelihood of the 1/4" rise from p-trap to the drain causing a future drainage problem. The sink drain is inches above the wall drain, and the water should still drain without problems.
3) Recommendation? Pull the vanity, open the wall, and raise the vent/drain "Y" intersection up to the level of the drain pipes in the wall? Of connect the drains as pictured and don't worry about it unless the inspector requires the change?
Thanks for reading, and for the feedback. One thing I've learned during this build is that there's a whole lot more knowledge associated with proper drain construction and I realized. I've learned a lot. (Paid the price, too.)
Scott
A professional plumber completed rough in, and passed inspection. However, when the vanities came in, the drain lines were positioned too low on the wall. I would have had to cut the bottom of the vanities in half to put the P-trap down low enough to meet the drain line. So I've made modifications, and am in the process of installing the finish plumbing and drains for the Master. I believe that I've messed up, and want to verify this before pulling out vanities, messing with granite, and ripping out walls (again!!).
I first realized the problem when the granite company arrived to set the counter tops. The vanities are "stand alone" and were not set when they arrived. The granite guy is an outstanding contractor, and attempted to help me by setting the first two vanities. He cut the base of the vanity to meet the drain height, and we agreed that he should stop there and let me finish plumbing and vanity install. It just wasn't working out.
This is what I worked out. (Get ready for some "plumbing".)
I realized when researching the Master vanity drain install that the Weir is not supposed to be higher than the vent. The vent is at the level of the top of the Sani-tee, which is lower than the P-trap weir. Thus this will be a "fail" at inspection (i.e. water could siphon out of the P-trap, because there's no vent break). I'm pretty sure that I need to tear this whole thing out, raise the sani-tee up six inches or so, and re-install with a straight pipe out of the p-trap angles slightly down to the sani-tee. Can someone confirm this, or offer a better option?
Second, similar issue. As illustrated in this rough (emphasis, ROUGH) drawing, the original installation had the double vanity drains split at the vent/drain intersection, with an elbow at either end (and a straight pipe stub from the elbow out the wall). To raise the drain lines height to meet the required vanity height, I opened the wall and added two elbows at either end of the drain line, one pointed upward, an approximately six inch pipe, and one at the top of the pipe pointing out of the wall. The problem is that the weir is now also six inches above the vent pipe.
Second, I apparently can't use a measuring tape, because the drains are too high. As illustrated in the picture below, the straight pipe from the P-trap back to the wall is angled up about 1/4", rather than down. Again, while I want my home plumbed correctly, a larger part of this is the final plumbing inspection. This is angle is slight enough that an inspector might not notice unless he puts a level on the pipe. And to be honest, having 1/4" water retention in the pipe just makes the p-trap an extra six inches or so long. The over riding issue is the design of the drain/vent/weir. Even if the inspector pass this, I'd know it's wrong behind the wall. Then again, how big an issue is this from a practical perspective. There are two vanity drains connected to the same 2" drain pipe.
1) What's the likelihood of a siphon being created that pulls the water out of either vanity drain p-trap?
2) What's the likelihood of the 1/4" rise from p-trap to the drain causing a future drainage problem. The sink drain is inches above the wall drain, and the water should still drain without problems.
3) Recommendation? Pull the vanity, open the wall, and raise the vent/drain "Y" intersection up to the level of the drain pipes in the wall? Of connect the drains as pictured and don't worry about it unless the inspector requires the change?
Thanks for reading, and for the feedback. One thing I've learned during this build is that there's a whole lot more knowledge associated with proper drain construction and I realized. I've learned a lot. (Paid the price, too.)
Scott
Last edited by a moderator: