another vent pipe question

[dug]

I ran one of my vent stacks out a wall up high tucked under the eave, and will cut a hole in the roof and run it about a foot above the roof and seal it with a boot. It was easier and I'll never have to worry about an undetected leak soaking the insulation in my wall. Also it is on the back side of the house where only the cows on the ranch behind us can see.

I was going to run the other stack the more conventional way, straight up the wall and through the roof, but am now considering doing this one the same way as the other- for the same reasons.

Besides being a possible code violation is there any other reasons not to do it this way? Aside from aesthetics?

[Alan Gage]

In areas with snow you'd have to worry about a whole roof full of snow sliding down and wiping out the pipe.

Alan

[MountainDon]

That's one of dug's lesser worries.  

If it's going through the roof anyhow I'd run it straight up and use one of those silicone boots on the roof. They are darn near "bulletproof" when carefully installed.   (We shaped ours to the roof first, then pulled it up and applied silicone sealant under the flange and then screwed it down being careful not to tighten the screws too much which can distort the seal.)  My 2 cents worth.

[dug]

Yeah, no snow worries. I bought a boot flashing today at a metal roof store but after looking at it here it seems it would have a little trouble working correctly on the 45 degree pitch. The bottom side of the vent pipe touches the edge of the inside bottom portion of the flashing before it quite gets to 45 degrees, and the rubber distorts and buckles quite a bit. Maybe not a problem but it doesn't look so good.

The main reason I'd rather do it this way (aside from being easier in several ways) is that because my soffits are not closed so a small leak wouldn't really hurt much, and could be detected.

It's hard being me. 

[Squirl]

So, I just read the last post you had about DWV.  I've been racking my head around this for the last few days myself.  I read that there is no toilet.  Have you considered AAV's (Air admittance valves)?  I have one drain (kitchen sink) that is off in left field and I was looking into it because it supposidly doesn't need to go through the roof.  I hope I don't high jack it to much, but does anyone know much about these?

[MountainDon]

link to Studor design criteria

http://www.studor.com/DesignCriteria.pdf



and the Oatey

http://www.oatey.com/apps/catalog/instance_assets/assets/OAT_AAV_SVA_link3.pdf

[Alan Gage]

It's hard being me. 

You're not alone. I've thought that same thing many times during my build when my brain gets hung up on silly things.

As for AAVs I'm planning on one for my kitchen sink so I'll only have one vent pipe through the roof. If you do some research online you'll find plenty of people with a strong distaste for them. I found very few incidents of actual failures though, at least on the newer valves. I believe the older designs had more moving parts and were prone to failure. From what I've read the newer ones are a bit more reliable. Perhaps that's why so many hard feelings still exist.

I try not to be cynical but I got the impression from my research that the biggest beef people (plumbers) had with them was that they were something different and made venting too easy.

Alan

[Redoverfarm]

Dug I just installed one on mine Sunday.  Yes it is a tight fit with the 10/12 pitch and the boot being about 8" square but I was able to pull some and made it work.  The one I took off (previous snow damage) was the same way and never leaked. Just a little insurance other than placing caulk under the seal is to run a bead around the edge as well.  Mine did not buckle and looks fine just a little close to the pipe on the bottom side.  But it does cover the hole.  

[dug]

I read that there is no toilet.

There isn't, and there may never be but I plumbed for one anyway in case my wife overrides my outhouse plan down the road. I am doing a grey water system like this one-



If I use a backwater valve like they show an air admittance valve might just be the ticket. On my setup the potential future toilet and bath sink are connected to a separate vent to the outside, which is already done. The shower and kitchen sink are the ones I've been dealing with and I already have the pipe run to the upstairs wall. Could I just put an AAV valve on there?

Redoverfarm- Thanks for the first hand info that the boot will work I.K. I'll give it a try.

[Redoverfarm]

Dug I know that they do make larger boots.   But depending on where on the roof the pipe penetrates will determine the size.  If it is close to a raised portion then larger is not necessarily better in that you have to bridge that peak in the roofing profile.  My pipe penetrates right in the center of the valley adjacent to the seam peak so that boot was suited for the location and it was the only one available locally.  Now if yours falls in the middle valley then maybe a larger boot might be justified.

This is the one I used  (standard)  
http://www.bestbuymetals.com/store/pipe-boots.html?gclid=CO24v_OD6aoCFWJd5Qod2HAgNg

I don't know the color of your roof but get yourself a can of spray paint and after installing you can paint the pipe to be less noticable.

Continuing in your conversation make sure i you install a studor valve that it is not enclosed in the wall cavity.
It has to draw air to make it work.  If it is in an air tight area it might not work right.

ED: fixed link - MD

[Alan Gage]

Continuing in your conversation make sure i you install a studor valve that it is not enclosed in the wall cavity.
It has to draw air to make it work.  If it is in an air tight area it might not work right.

ED: fixed link - MD

I think the main reason they can't be buried in a wall is because if they fail they start flooding your house with sewer gas. Makes it hard to fix if no one knows where it is.

They can be installed in a wall cavity as long as there's access.

Alan

[Squirl]

A few of the books and posts I read also recommended a lead flashing boot instead of a plastic one.  I don't how good the information is, but they say it lasts a lot longer.  I certainly wouldn't do it if you are using your roof for potable water.  Also all the installations I saw it on had shingles.


I did see some complaints that AAVs are only warranted for so many years (usually 20).  The way I'm looking at it is that it does not seem like a major problem to me.  If it does fail, it screws in and out and is very accessible.  No real damage, just a bad smell. If my roof vent fails, that is hard to notice and a lot more difficult and expensive fix.  I have also seen that they make little vented boxes for placement in walls.



http://www.plumbingstore.com/automatic_air_vents.html

[archimedes]

I used an AAV on my cabin kitchen sink.  Used it for five years (until I sold the property).   Never had a problem.   The sink was on an island,  so it sure made the plumbing easier.

Even it it fails,  you just unscrew the old one and replace it with a new one.

[Erin]

If AAVs are relatively reliable, what is the reason one would go with a vent stack?  Or are they simply not reliable enough?