DIY vent design

[wwhitney]

I am just outside Denver CO. I believe I am under 2021 IPC

Edit: forgot to hit post, so this response is untimely. Will followup shortly.

Yes, CO uses the IPC per up.codes. Also, CO has adopted the plumbing portion of the IRC, so assuming this is a single family home, your horizontal wet vent would be subject to IRC P3108.1 which requires that any wyes between a fixture drain and the wet vent venting that fixture be horizontal.

Chapter 31 Vents: Vents, Colorado Residential Code 2021 | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

But with the IPC, you do have the option to simplify your lav drain routing, by connecting it directly to the WC drain (with a horizontal wye, not from above), and then connecting the shower drain downstream of that. That assumes that your shower trap arm would be under 8' in length.

Cheers, Wayne

 

[wwhitney]

Last drawing looks good, minor comments:

- To confirm, after you remove the 90 in the shower trap arm, you should have a single 45, and the length of the two pipe segments on either side of it, plus the 45, needs to be 8' or less.

- When you say 2" standpipe with cleanout, the cleanout should be in the 2" drain below the san-tee.

- Your two new 1.5" dry vents can tie in to basically any existing dry vent (vent through the roof that receives no drainage from above), as long as the connection point is at least 6" above the flood rim level of any fixtures served by any of the connecting vents.

Cheers, Wayne

 

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[Graham Love]

Edit: forgot to hit post, so this response is untimely. Will followup shortly.

Yes, CO uses the IPC per up.codes. Also, CO has adopted the plumbing portion of the IRC, so assuming this is a single family home, your horizontal wet vent would be subject to IRC P3108.1 which requires that any wyes between a fixture drain and the wet vent venting that fixture be horizontal.

Chapter 31 Vents: Vents, Colorado Residential Code 2021 | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

But with the IPC, you do have the option to simplify your lav drain routing, by connecting it directly to the WC drain (with a horizontal wye, not from above), and then connecting the shower drain downstream of that. That assumes that your shower trap arm would be under 8' in length.

Cheers, Wayne

Wayne,
That all sounds good, updated drawing attached. Thank you for the attention to detail!

 

[Graham Love]

Last drawing looks good, minor comments:

- To confirm, after you remove the 90 in the shower trap arm, you should have a single 45, and the length of the two pipe segments on either side of it, plus the 45, needs to be 8' or less.

- When you say 2" standpipe with cleanout, the cleanout should be in the 2" drain below the san-tee.

- Your two new 1.5" dry vents can tie in to basically any existing dry vent (vent through the roof that receives no drainage from above), as long as the connection point is at least 6" above the flood rim level of any fixtures served by any of the connecting vents.

Cheers, Wayne

Updated drawing.

 

[wwhitney]

Updated drawing.

Looks good.

Only comment is that you show the shower trap arm hitting a wye with no intervening elbows at all. That you could do if you point the trap outlet at a 45 degree angle to the WC drain. But then the distance from the WC drain to the trap outlet (measured perpendicular to the WC drain) would need to be at most 8' / sqrt(2) = 5.6'. Mostly like you'll want to point the shower trap outlet perpendicular to the WC drain, then use a 45 not far away from the WC drain, then a wye (which must be downstream of where the lav joins the WC drain).

Cheers, Wayne

 

[Graham Love]

Looks good.

Only comment is that you show the shower trap arm hitting a wye with no intervening elbows at all. That you could do if you point the trap outlet at a 45 degree angle to the WC drain. But then the distance from the WC drain to the trap outlet (measured perpendicular to the WC drain) would need to be at most 8' / sqrt(2) = 5.6'. Mostly like you'll want to point the shower trap outlet perpendicular to the WC drain, then use a 45 not far away from the WC drain, then a wye (which must be downstream of where the lav joins the WC drain).

Cheers, Wayne

I like that a lot, less concrete to remove. I've updated the drawing to show 7'10" shower trap arm/ wet vent. The design has come a long way since yesterday... What can I say, Thanks a million to all of you!

 

[wwhitney]

7'10" shower trap arm/ wet vent.

Since you're cutting it close, you can shorten the shower trap arm by shortening the portion of it at a 45 to the 3" drain, i.e. move the elbow closer to the 3" drain. But as it must join after the wye from the lav, you'd need to move the wye from the lav closer to the closet flange. Which you can do by moving the san-tee in the wall, and thus the vent and vertical lav drain, in the same direction, at the expense of a longer horizontal lav trap arm, but you have plenty of flexibility there. So doing that could give you a bit more cushion on your trap length and getting the slope exactly 1/4" per foot.

The other option for getting more cushion is to point the outlet of the closet bend under the closet flange at a 45 from the wall (rotate it 45 degrees from above towards the shower). Then the lav would have to travel a bit farther under slab to hit the WC drain, but the shower trap arm wouldn't have to travel as far. After the shower drains, the WC would hit a 45 to turn parallel to that wall, then another 45 to line up directly with the diagonal orange pipe you have labeled "to street."

Those are just options, if your length comes out to exactly 7' 10" with the fall exactly 2" - 1/24" to 2", that's perfectly fine. Just a tight tolerance to hit.

BTW, the fitting at the bottom you have labeled "3/3/3 st combo wye" (not sure what st means) is something that doesn't exist. You have two incoming pipes at right angles and the exiting pipe at an angle. You'll need to use multiple fittings to do that. Which is one reason that having the 3" WC drain come into that location at a 45 from how you have it now (in line with the "To street" line) would be maybe a plus, you could just use a regular wye there.

Cheers, Wayne

 

[Graham Love]

Since you're cutting it close, you can shorten the shower trap arm by shortening the portion of it at a 45 to the 3" drain, i.e. move the elbow closer to the 3" drain. But as it must join after the wye from the lav, you'd need to move the wye from the lav closer to the closet flange. Which you can do by moving the san-tee in the wall, and thus the vent and vertical lav drain, in the same direction, at the expense of a longer horizontal lav trap arm, but you have plenty of flexibility there. So doing that could give you a bit more cushion on your trap length and getting the slope exactly 1/4" per foot.

The other option for getting more cushion is to point the outlet of the closet bend under the closet flange at a 45 from the wall (rotate it 45 degrees from above towards the shower). Then the lav would have to travel a bit farther under slab to hit the WC drain, but the shower trap arm wouldn't have to travel as far. After the shower drains, the WC would hit a 45 to turn parallel to that wall, then another 45 to line up directly with the diagonal orange pipe you have labeled "to street."

Those are just options, if your length comes out to exactly 7' 10" with the fall exactly 2" - 1/24" to 2", that's perfectly fine. Just a tight tolerance to hit.

BTW, the fitting at the bottom you have labeled "3/3/3 st combo wye" (not sure what st means) is something that doesn't exist. You have two incoming pipes at right angles and the exiting pipe at an angle. You'll need to use multiple fittings to do that. Which is one reason that having the 3" WC drain come into that location at a 45 from how you have it now (in line with the "To street" line) would be maybe a plus, you could just use a regular wye there.

Cheers, Wayne

copy that.
what do you think of these minor changes (shown in attached):
-connect shower trap to 3" WC drain after 45- shortens trap arm ~1' & can use regular wye
-connect WM drain line- shortens drain distance & can use regular wye

 

[wwhitney]

Looks good to me. You may get more responses if you cut and paste an image file, rather than a PDF, as then it will appear inline, rather than requiring a download. [Unless my browser is weird and others show it inline already.]

One final comment--I believe best practice (possibly a requirement) is to provide a cleanout for the 3" WC drain. That's difficult to do for the entire length, but not hard to do starting at the wye where the lav joins. Namely you can upsize the under slab 2" lav drain to 3", and bring it up into the wall as 3", and use a 3" cleanout fitting under the lav, with a 3x2 bushing in the top of the cleanout tee to receive the 2" lav drain from the san-tee above it.

Cheers, Wayne

 

[Graham Love]

Looks good to me. You may get more responses if you cut and paste an image file, rather than a PDF, as then it will appear inline, rather than requiring a download. [Unless my browser is weird and others show it inline already.]

One final comment--I believe best practice (possibly a requirement) is to provide a cleanout for the 3" WC drain. That's difficult to do for the entire length, but not hard to do starting at the wye where the lav joins. Namely you can upsize the under slab 2" lav drain to 3", and bring it up into the wall as 3", and use a 3" cleanout fitting under the lav, with a 3x2 bushing in the top of the cleanout tee to receive the 2" lav drain from the san-tee above it.

Cheers, Wayne