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Toilet Flange inside fit 3.5"?

23058 Views 5 Replies 3 Participants Last post by  Ghostmaker
The toilet flange I've pulled is an PVC 3.5" inside fit flange.

The house and sched 40 DWV PVC pipe are both 40 years old. I cleaned up the inside of the pipe below the floor where the male flange fit into, measured the ID, and it's 3.5".

I see 3" and 4" replacement flanges, but no 3.5" flanges. Am I measuring correctly? If so, was this a limited run from the 70's, and can I find a replacement?

I've got decent building experience but limited plumbing experience. This is my first closet flange replacement.

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I assume your location is in America. Could be you're not measuring correctly, try using a string then measure the string. Post a picture of the flange and closet bend. Thanks.

Do you have access from underneath? If so, post a picture of that to. Thanks.

The plumbers will be along shortly.
Yes, U.S. location. I will measure again, and post a photo after work today, sometime around 6PM central. I do have access underneath, and will include that photo.

Thank you.
What your measuring is the inside of a 4 inch drain. It is very normal for a plumber to install a 3 inch female toilet flange 3.5 inch outside diameter into the 4 inch pipe.
Get the same plastic and use a lot of cleaner and glue on both. Also buy a flange with the stainless steel ring.
Thanks jmon & Ghostmaker, you are absolutely right. The 3x4 flange slipped right in - 3.5" ID into the 4" drain pipe. Beginner stuff.

I did buy cleaner, I will use it liberally.

Question - I gouged up the inside of the 4" drain pipe a bit removing the old flange. My cuts went into the pipe maybe 1/64", and I gouged out a few fingernail diameter pieces also about 1/64" deep, about 3/4" deep into the drain pipe. Will PVC cement do a good enough job to gap those cuts? Does a gap filler/putty exist to use in PVC joints?

Does the stainless ring make that large of a difference? I currently have one without, and it has eight holes to secure it to the floor with wood screws. Does the plastic fatigue and crack over time from multiple seatings without the steel ring?

How much should the flange insert into the drain pipe as a minimum? I may have to buy a flange with a longer neck, if made. I plan to install flange on top of backer, then tile up to the flange. Looks like the flange will insert into drain pipe about 1", maybe just under.
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The all plastic flanges will break. See if you can find a longer flange you need a 1.5 inch joint or better. Also make sure you get the glue. Primer without glue is no good.
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