The vent is open-- as the name implies. Pour water into the drain of each fixture to fill the individual TRAP for that fixture. As the name implies, it traps sewer gases to prevent them from coming into the living space. Fillings the traps once a week should be sufficient. Valves? What device are you calling a valve?

JDS and Joe don't laugh at my lack of knowledge but explain something to me. We have wooden hexagon shaped attic vents in three gable ends. See link below - mine are similar to this. I need to remodel a bathroom and install an exhaust fan. Can we run the duct work to the exhaust fan out the hex attic vent? I would use the one closest to the bathroom of course. If so, how does the duct attach to the attic vent? I am assuming there are some type of clips or fasteners or thing-a-ma-jiggies that does that. DH and I DO NOT want to go through the roof, but would if absolutely necessary. I had always assumed we would need to go through the roof so this discussion may help solve our problem. Joe don't you dare get sarcastic - just tell me if I am on the right track. I would hire you to do this if you were in Kentucky :). And I wouldn't get three quotes. Hex wooden attic vent

Btw, I searched for relevant codes and found the following: R304.1 Minimum area. Every dwelling unit shall have at least one habitable room that shall have not less than 120 square feet (11 m2) of gross floor area. R304.2 Other rooms. Other habitable rooms shall have a floor area of not less than 70 square feet (6.5 m2). Exception: Kitchens. It also states: In typical houses, all living, sleeping, eating or cooking areas qualify as habitable spaces. Bathrooms, toilet rooms, closets, halls, storage or utility spaces aren’t defined as habitable, for any dwelling. But anyway you slice it, even with the remodeled floorplan the upstairs certainly meets the minimum requirements. The master bedroom is a little over 120 sq ft, and the second bedroom is over 70 sq ft (approx 90 sq ft). Even if the master bedroom didn't quite meet 120 sq ft, other habital areas such as the downstairs living room is well over 120 sq ft, so it'd just need to exceed 70 sq ft, which it certainly does. The only codes I could find regarding bathrooms were ceiling height (which wouldn't be an issue) and minimum distances between toilet, sink, shower and tub: A minimum space of 21 inches must be planned in front of lavatory, toilet, bidet, and tub. A minimum space of 24 inches must be planned in front of a shower entry. The minimum distance from the centerline of the lavatory to a wall is 15 inches. The minimum distance between a wall and the edge of a freestanding or wall-hung lavatory is 4 inches. The minimum interior shower size is 30x30 inches or 900 square inches, in which a disc 30 inches in diameter must fit. A minimum distance of 15 inches is required from the centerline of a toilet and/or bidet to any bath fixture, wall, or other obstacle. I don't see a problem with meeting any of these (depending on size of tub or shower, toilet, sink, etc.), which is why the plumbing issue seems to be the sticking point to me.

Mystery solved. (See my earlier post for the steps I had already taken to try to get a plumber under the house without success.) I scheduled two crawl space inspectors offering different services, thinking the joists under the bathroom would have to be replaced. The first one said that he didn't see anything serious under the bathroom, and the joist looks fine, but they saw some standing water under the kitchen. he said he wasn't sure if there was a problem or if there had just been some heavy rain. So then I was able to call a different plumber and say "we have standing water under the house." I feel what happened next is an example of exemplary service and professionalism. Even though the old copper pipes had been replaced about 15 years ago, there was a cast iron pipe has had corroded that only handled grey water. (It's not clear why this would have been replaced 15 years ago also, but anyway....) A team of two came out a few days later, did the work in the morning, provided photos and then one of the plumbers said... "We also were under the bathroom and saw that you have a leak from your toilet, so we are going to fix that for free to make sure the job is done right." (He showed me photos from under the house which were similar to the ones I originally posted.) Now all fixes have been made as far as I I know. We have a second crawl space person coming in next week and we're going to keep that appointment. The earlier estimate pointed to other kinds of work that could be done under the house - not sure if we need it, but since one raised the idea we want to match opinions to find out if we have any other problems under the house. Thank you for your responses, they helped me to keep looking and not give up.