I was reading some other posts about setting the toilet flange at the height of a finish floor. Most suggestions seemed to include leaving the flange loose until the finish floor is in (I assume a test ball is then used for pressure test).

I found some nice flanges with stainless steel rings that have a sealed knock-out for pressure testing, which would save me the cost of buying a few test balls for a one-time deal. Of course, If it is to seal the system it obviously has to be glued on at the time of the pressure test.

Around here, it seems common practice to glue the flange to the sub-floor and I assume that they use spacers later on. It sounds like must of you pro's discourage that.

What is the best way to glue the flange, but allow for the finish floor?

Just don't glue the flange on until the floor is finished. Take the hit, buy a test plug of the proper size for the drain line and install it. This will stop sewer gas and protect the system from having debris introduced into the drain system. I had to demo a wall last night to remove a portion of cast iron soil pipe that appeared to have a large section of throw rug caught inside. If someone had used a test plug instead of stuffing junk inside the stool hub, a lot of time and money would have been saved.

if you know the exact height of the finish floor you can set the flange using spacers. some areas require the flange to be set before getting the rough inspected. it is always better to set the flange after the floor is finished though.

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If I have a choice I stub up with 4" pvc and then install a 4x3 flange that glues inside 4". Anchor to slab with nail-drive anchors or stainless screws to wood. That way if the flange ever needs to be replaced its easier to remove. I never use the adjustment slots I use the fixed slots for my closet bolts. Also the 4" stub up allows a cheap glue-on test cap or a fernco cap.

Unless the inspector is requiring the flange to be glued on at rough inspection, leave the pipe run a little long and glue in an insert test cap or a standard outside cap.
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In my area its rare not to start the rough plumbing process without putting the closet collars down 1st. Then work the whole house off the toilets. Ive only seen someone leave a 4" pipe sticking up to be cut down later once in 9 years. If its tile or hardwood just cut 6- 3/4" long pieces of 1/2" copper and use long screws.....Its solid as a rock and ive never heard of anyone having a problem.

putting the collars down on the finish seems like alot of extra work...Also you could slip and scratch the floor with the sawsall...

easy enough especially wen the toilet would cover any scratches but then they d make inside cutters that wont scratch the floor. i have rarely installed the flange before the floor was finished. it makes for a much better install imo. but 10 plumbers will do the same thing 10 different ways and all could be correct.

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PLUMBERS "Protecting The Health Of The Nation"

I do exactly like waukeshaplumbing does.

Whatever you do you want the flange to be on top of the floor and secured with #12 brass or stainless steel screws that secure to all the floor material(not just 3/4"

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Thank you all for your helpful input!

Since test balls appear to be about $30 each and I have 3 toilets, I think I will avoid going that route. A cheap cap on a 4" stub sounds like an economical solution, but, that would require lengthining the closet bend by only an inch or 2, which seems to me to be impossible given the space and fittings I have to work with. I will talk to my inspector tomorrow and see if he wants flanges secured at rough-in.

The insert caps can be glued to the exact length stub if you use an outside flange. You cut out the center of the plug and glue the flange on.

just don't knock the cut out down the pipe.

So if you dont have 6 3/4" pieces of copper you cant set a toilet flange. You can scratch the floor so many ways I dont care to list. I use a saw then get to the exact with an inside pipe cutter in a drill.Floorman can cut as close as he can to the pipe so my flush-fit flange will be totally supported. Theres no better way of doing it period. And as I said its easier to change the flange if the floor level ever changes because it solvent welds inside 4" pvc.