Toilets, Sinks, Showers, Tubs and Disposals - New shower pan/drain --- need help with drain

I am installing a new shower base and the existing drain is 1.5" and the no caulk shower thingy is 2" --- my drain is right over a joist. I cut down to accept a 1.5" trap instead of using a 2" trap casue then I would have to cut much more out of the joist. The guy at Home Depot said this trap would be ok ?? Any sggestions? Also --I added a whirlpool tub to this --- does this tub need to be vented seperatly or can I add it to the exitsting venting?

Before remodel there was a toilet,tub,and vanity --- now there is a shower,tub,and 2 pedastol sinks.

Any help would be appreciated

thanks

UPC, and I think IPC, require a 2" drain for a shower, which is why you shouldn't ask the people at the box for code advice!

As to the vent, we would need to see a picture or diagram of what you propose. A pipe can vent more than one fixture, if it is the right size and installed properly.

REINVESTOR: Agree with 594tough, your line for your proposed hook-up is too small, sorry.

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"If all else fails, read the directions"