Reducing roof vents in roof replacement

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Reintree

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Putting on new roof (with new plywood sheathing) on mid-70's 2-story house. We're in unincorporated King County WA, 502 ft above sea level. Septic system pumped regularly. Surrounded by cedars, so often get large branches whacking on roof. Squirrels, raccoons, etc. at times.

Would like to improve, or better, eliminate, 2 existing roof plumbing vents on front roof (esthetics, occasional heavy snow load, and previous leak issues). I assume the 2 vents are for the ground floor sink/toilet and the 2nd floor sink/toilet/bathtub, which are vertically one above the other. Toilets are Totos installed by Love Plumbing 3-4 years ago.

Have recently read about Air Admittance Valves (eg Studor, Oatey). We would leave other bathroom roof vents (at least one, as I believe is required) in place. Assuming that AAVs are ok by code, would appreciate some advice on the following:

1. how would a plumber verify that the 2 bathrooms on the front of the house are using the 2 existing front roof vents and that one or both could be "converted" to using AAVs? Aside from diagramming the visible fixtures and connections, would the plumber need to look into the attic? If so, just a pop head and good light through access door or would they need to crawl into attic? It's fairly low slope and not easy to access.

2. Understood about the possibility of needing access panels cut into walls for bath or toilets.

3. What happens to the "old" stack pipe, does it need to be removed completely or can it just be "capped" below and left in place running up into the attic but cut off and capped below the roof deck?

4. All work would be done by a licensed plumber. Does this kind of work require an inspection?

5. How much work is involved, assuming things go well, i.e. one visit to determine work, second visit to complete? The reason I ask is that we need to coordinate with roofing progress to avoid having open penetration. The existing roof is very fragile, so we can't have anybody up there to remove vents or cover them over prior to the new roof being started, but if we need Co. inspection then that will complicate the timing.

I hope the following picture will help explain. Thank you for your comments.

LoveForum.jpg
 
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Jadnashua

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AAV's, being mechanical, wear out and fail eventually, they have their place, but also note, they won't work everywhere...they only let air in, and depending on what's going on, may need to let air out as well, but they can't. Depending on how they are run, you may be able to combine them to minimize the roof penetrations required. Your best bet is always to do it without an AAV.
 

MikePlummer

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why not tie the 2 vents together in the attic and run just one through the roof, thus eliminating one penetration? removing proper vents in favour of AAV's goes against any sense of good plumbing procedure and will more than likely leave you with venting issues down the road
 

Terry

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Even with AAV's, you still need a vent (s) through the roof somewhere. In King County, you either need a single 3" vent, or two 2" vents and a 1.5" vent, which will equal the area of the 3" vent.

It may be that the 2" vent to the right is for the toilet, and the 1.5" to the left is for the lav.
When the new roof is installed, the leaks will be gone. A new roof normally comes with new roof jacks.
The entire Northwest is plumbed the way your home is now. Not much has changed since the 70's

The snow load in Woodinville is rarely over 10", and the longest I've seen it last is seven days. At least since 1960. We did have heavier snows in the 50's. In fact in the early part of the 1900's, Lake Washington used to freeze over between Mercer Island and Bellevue. Where you live is 10 degrees hotter in the Summer, and 10 degrees colder in the Winter than Seatac. At least that was my expirence when I was living there. My son James was born a few blocks from where you live, at home.
 

MACPLUMB

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Go into attic with vent pipe materials cut those off where they come up through ceiling put 45 bends on and turn back behind roof peak and bring up there, do away with existing vents though roof with new roofing,
 
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