SkullMesaRanch Posted August 15, 2023 Share Posted August 15, 2023 I hate to admit that I got this far (almost done with the construction docs) and now may have to redesign the master bath. After working on the MEP and reading through the IRC, I found the spec for max distance of fixture trap from vent (6' for 1.5" pipe, 8' for 2" pipe, and 12' for 3" pipe.) With the master bath layout shown, I'll have to put the 3" vent in an external wall next the the sink (shown in green) to meet the 6' to 1.5" trap (restricted by the window). The distance from the proposed vent to the tub trap would be slightly over 8' and slightly over 12' to the toilet trap. I'm I missing something or you just can't have big bathrooms? This is a bathroom floor plan I found online and liked. The room above is a master bedroom/closet and the room below is the garage. What would you do? bathroom.pdf Link to comment Share on other sites More sharing options...
ACADuser Posted August 15, 2023 Share Posted August 15, 2023 Look up "wet vent" Link to comment Share on other sites More sharing options...
ACADuser Posted August 15, 2023 Share Posted August 15, 2023 The blue line is a wet vent https://www.pmmag.com/articles/102031-we-might-get-letters-a-horizontal-wet-venting-leap-of-faith Link to comment Share on other sites More sharing options...
DrawingABlank Posted August 15, 2023 Share Posted August 15, 2023 You could just plan to vent them separately until they can reconnect in the attic or in this case the floor system. Link to comment Share on other sites More sharing options...
Bob-Roraback Posted August 15, 2023 Share Posted August 15, 2023 Good relevant article JLC Online Article PDF_ 0915b_JLC_CEV_L.pdf.pdf Link to comment Share on other sites More sharing options...
SkullMesaRanch Posted August 16, 2023 Author Share Posted August 16, 2023 Hi ACA, I do understand wet vents. I'm just trying to figure out how to physically connect the vents. I think your sketch implies combining the master bath vents in the attic instead of the walls. Link to comment Share on other sites More sharing options...
SkullMesaRanch Posted August 16, 2023 Author Share Posted August 16, 2023 16 hours ago, DrawingABlank said: You could just plan to vent them separately until they can reconnect in the attic or in this case the floor system. Ok, so that's how you get around the code restriction. This approach takes more material. Would that also be better than routing a drain vent horizontally under the window (going thru king studs)? If I move the window... butted up against the wall, I can move the main vent closer to the bath and toilet and meet the code. I'm not sure if it's a good idea to butt a window up to a wall. Link to comment Share on other sites More sharing options...
SkullMesaRanch Posted August 16, 2023 Author Share Posted August 16, 2023 16 hours ago, Bob-Roraback said: Good relevant article JLC Online Article PDF_ 0915b_JLC_CEV_L.pdf.pdf 8' 172.61 kB · 8 downloads Thank you. Aren't sink traps 1.5"? This article implies that the sink vent line is 2" (due to the distance of 8' to trap.) Apparently they can be either. Link to comment Share on other sites More sharing options...
ACADuser Posted August 16, 2023 Share Posted August 16, 2023 If you need to run the Arm 8' use a 2" arm. You can still use a 1.5" trap. You have to measure from the weir. If you need less than 5' of arm use 1.5" pipe. Make the wall thicker if the 1.5" arm is a structural issue. If that doesn't work for you some jurisdictions allow an "Auto Vent" to be used inside the vanity. This is how I would layout the piping. Link to comment Share on other sites More sharing options...
ACADuser Posted August 16, 2023 Share Posted August 16, 2023 If you put the stack directly behind the lavatory you often conflict the vent stack with the light electrical box above the vanity. So you have a very short arm or the have to offset the stack pipe below the light fixture. Link to comment Share on other sites More sharing options...
DrawingABlank Posted August 16, 2023 Share Posted August 16, 2023 54 minutes ago, SkullMesaRanch said: Would that also be better than routing a drain vent horizontally under the window (going thru king studs)? Looks like due to the height of the window the horizontal vent under the window will not work. The vent needs to raise above the sink 'full line' before moving horizontal. (Limits 'dirty vent' should sink ever plug up.) Sure there are a few more fittings and a stick of 1.5" but that is the trade off sometimes for design preferences. I would vent the sink by itself up into floor system before trying to tie it to a 3" vent in an exterior wall. (harder to insulate properly) Alan has a good reminder on keeping clear of other needed MEP in the wall. Link to comment Share on other sites More sharing options...
SkullMesaRanch Posted August 16, 2023 Author Share Posted August 16, 2023 You guys are really helpful. I've been given a few options and even got an isometric from Alan. I'm confident I can now come up with a solution to this without changing the layout of the master bath. It's looking like a smaller window would help but a separate vent for the sink will solve the problem without any mods. Thank you, all! Link to comment Share on other sites More sharing options...
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