Minimum P-trap Distance Requirement?

[Thomas K]

I've been installing new vent lines yesterday and today in upstairs bathroom because I moved tub area over to make room for stackable washer & dryer . I am going to use 2" glued P-trap for tub with 1.5" reducing bushing for tub drain. Here is my delimma:

I installed 2 x 10" blocking where feet of new cast iron alcove tub will sit for added support. This left it tight for the P-trap and sanitary tee. I am wondering if there is a minimum pipe length where drain pipe runs from P-trap to sanitary tee. I'm thinking a minimum of 4", but I may be wrong.
Also, is it okay for 6-7" vertical drop after sanitary tee? I'm tying into a 2" drain line on floor below that was for washer there.

Thanks for any replies!

 

[Reach4]

I am wondering if there is a minimum pipe length where drain pipe runs from P-trap to sanitary tee. I'm thinking a minimum of 4", but I may be wrong.

2 pipe diameters for 2 inch pipe is 4 inches.

 

[Sponsor]

 

[Kreemoweet]

The way DWV plastic pipe is made, it's not possible to violate minimum trap arm length rule with glued trap and santee
without actually cutting down one hub or another. In other words, "zero" length pipe between the two fittings is OK.

There is no limitation on vertical drop below santee.

 

[Thomas K]

2 pipe diameters for 2 inch pipe is 4 inches.

Thank you!

 

[Thomas K]

The way DWV plastic pipe is made, it's not possible to violate minimum trap arm length rule with glued trap and santee
without actually cutting down one hub or another. In other words, "zero" length pipe between the two fittings is OK.

There is no limitation on vertical drop below santee.

Thanks! That last sentence really eased my mind! I do have one question...This tub drain flows into drain for kitchen sink (all 2" pipe) almost at point where 2" pipe enters under-cement 4" cast iron sewer line. Is having these two on same line ok? And would it be okay to add a downstairs sink drain into same tub drain line?