Toilet vent question

[Bemis]

I'm installing the plumbing (DIY) in our small cottage in Maine. I'm a bit confused as to what I'm allowed to do with the venting. All plumbing is on the first floor and there is a full basement. The toilet flange is 8' from the vertical vent. My main waste pipe is to be 3" PVC as 4" is just too big for 1 bath and a kitchen sink - all low-flow. I understand that the max distance to vent is 6' with 3" waste; 10' with 4". I have the altitude to run a horizontal vent from the 6' point, pitched 1/4" to join the vent just above the waste line. Is that acceptable, or does the fact that the vertical vent is 8' away kill the deal?
Other info:
Shower drain is 2' from vent.
Lav is 7' from vent and will have an AAV (inspector allowed)
Kitchen is 6' downstream and will also have an AAV.
Venting is difficult to handle as its timber frame with SIPs and an open plan with only the bathroom partitioned off (wife insisted.)
So, before I ask the inspector - can I do the above? If not options?
Thanks
Bemis

 

[Reach4]

If the lavatory or shower are upstream of the toilet, and the kitchen is not upstream of the toilet, you may not need any extra toilet venting.

It is best to sketch and post your plan layout with a line diagram. If you know isometric drawings, that is a good way to draw your lines. You can draw your sketch in Paint.

 

[Sponsor]

 

[Bemis]

If the lavatory or shower are upstream of the toilet, and the kitchen is not upstream of the toilet, you may not need any extra toilet venting.

It is best to sketch and post your plan layout with a line diagram. If you know isometric drawings, that is a good way to draw your lines. You can draw your sketch in Paint.

Lav waste can be upstream of toilet - shower and kitchen would be downstream - I will rough sketch.

 

[Reach4]

Lav waste can be upstream of toilet - shower and kitchen would be downstream - I will rough sketch.

So lavatory, toilet, shower, kitchen, in that order. So kitchen needs venting. The toilet may not need its own vent. In UPC, shower would need its own vent, but in IPC (which I think Maine uses) it may not need its own vent since you you run 3 inch after the toilet. I am not a pro.

See https://wabo.memberclicks.net/assets/pdfs/Plumbing_Venting_Brochure_2018.pdf page 12.

 

[Bemis]

Yes - Lav waste could be joined upstream or downstream of toilet:
Option 1 - Lav with AAV > 4' > Toilet > 8' > vertical vent > 2' shower > 6' 6" > kitchen sink with AAV - see sketch
Option 2 - Toilet > 4' > Lav with AAV > 6' > shower > 2' vertical vent > kitchen sink with AAV
Maine uses a modified version of the UPC - local inspector approved the use of AAVs for both sinks.

 

[hj]

As you show it the shower may be NOT vented, and HOW did you make that "T" connection for the "vent to roof"?

 

[Bemis]

Thanks - no waste plumbing has yet been installed. Vent is in place - not yet connected. Shower drain is in place - not yet connected. Full basement with altitude to make connections any way. Connection to vent would be san tee. I can easily run a separate wet vent from the shower to the vertical vent.

 

[Bemis]

Adjusted drawing to vent shower just downstream of trap - better?