TN toilet vent question

Hi guys, I think this is easy but would be great if someone would confirm. Have a 3” toilet line and about 6’ downstream as the crow flies there is a sink drain that is vented, currently with 1.5”. Toilet is to the far left, lav is the drain on the right side.

I removed a wall that had another 2” vent for the toilet that was right at the capped pipe marked S for shower, there will be a shower hooked to the capped pipe and it will have its own vent on the other side of the room. Can I leave this as-is without increasing the 1.5” to 2”? I’m assuming that the went vent from the sink is allowed to vent the toilet and that it can be 1.5”. I can increase it if I need to just checking before I do. Thanks!

 

IPC allows a 1.5" lavatory wet vent for a toilet (and the shower, too, if desired). But the lavatory drain has to join one of the individual wet vented fixtures first (toilet, or possibly shower), then any other wet vented fixtures, and only then any dry vented fixtures can join in. That is, the separately vented fixture isn't supposed to drain through the wet vent.

Cheers, Wayne

 

Thanks but I guess I'm still confused, how is what I'm trying to do different from this from this? https://www.hammerpedia.com/how-to-vent-a-toilet/

Does it matter if it's 1.5 or 2"? I can make it 2" if needed.

The lav has a vent but there isn't anything above draining through it, it's just the lav and the vent if that helps.

 

Maybe I'm misinterpreting the last photo, but it looks to me like the future shower drain joins the WC fixture drain first, and then the lav drain joins the combination. The WC fixture drain needs to be vented before or as it joins another fixture drain, so the WC and the lav need to join, and then the shower can join in. Or if the shower is being vented by the lav, the lav and shower can join first, and then the WC can join in.

Cheers, Wayne

 

The shower will have it’s own vent. Probably would help if I made a diagram of all of it.

 

That would work for the shower wet venting the WC, instead of the lav wet venting the WC. Sorry for the confusion.

Cheers, Wayne