roundrightfarm
New Member
Greetings everyone,
I am getting ready to install a DWV system for new construction. 5 toilets total will be run through 2 DWV sub-systems that connect under the basement slab before exiting the house to the septic drain.
One DWV subsystem has three toilets. These are on the first floor, second floor and finished attic, and will all share a 3" drain stack, which will combo wye into a 4" drain, running horizontally in the first floor joists (first floor toilet has a 4" drain). This drain then drops through the basement to the septic drain.
I live in an area with no building codes, but If I understand good DWV design, I should not wet vent the first and second floor toilets through the soil stack because they have toilets above them.
question #1. For my first and second floor toilets, should I use a sanitary tee as a closet bend, which would then serve as a vent out the uphill end? If so, do I need to get vertical before reducing to a 2" vent, or can i do this immediately while still horizontal?
question #2. Since the attic is finished, there is not a lot of room to connect vents without going through the load bearing exterior walls. For a 2" pipe, the hole I would have to drill would be more than 40% of the 2x6 studs. Consequently, this house will have 4 or 5 roof penetrations for vents. I'm considering venting though the attic exterior walls rather than through the roof, since we also live in heavy snow country where ice dams can tear off roof vents.
I read a code that says you should not do this where the roof soffit is vented. Ours will be. Will this be a problem with a finished attic that is closed to the under-roof air space? is it ok for sewer gases to be under the roof line, especially after they have mixed with outside air?
Thanks for your advice
I am getting ready to install a DWV system for new construction. 5 toilets total will be run through 2 DWV sub-systems that connect under the basement slab before exiting the house to the septic drain.
One DWV subsystem has three toilets. These are on the first floor, second floor and finished attic, and will all share a 3" drain stack, which will combo wye into a 4" drain, running horizontally in the first floor joists (first floor toilet has a 4" drain). This drain then drops through the basement to the septic drain.
I live in an area with no building codes, but If I understand good DWV design, I should not wet vent the first and second floor toilets through the soil stack because they have toilets above them.
question #1. For my first and second floor toilets, should I use a sanitary tee as a closet bend, which would then serve as a vent out the uphill end? If so, do I need to get vertical before reducing to a 2" vent, or can i do this immediately while still horizontal?
question #2. Since the attic is finished, there is not a lot of room to connect vents without going through the load bearing exterior walls. For a 2" pipe, the hole I would have to drill would be more than 40% of the 2x6 studs. Consequently, this house will have 4 or 5 roof penetrations for vents. I'm considering venting though the attic exterior walls rather than through the roof, since we also live in heavy snow country where ice dams can tear off roof vents.
I read a code that says you should not do this where the roof soffit is vented. Ours will be. Will this be a problem with a finished attic that is closed to the under-roof air space? is it ok for sewer gases to be under the roof line, especially after they have mixed with outside air?
Thanks for your advice