Toilet flange height

Hello,
I am installing a new toilet in my shop with cement floor so where should the correct height of the flange be?

My plastic flange is almost a 1/2" thick .450 to be exact so should the bottom of the flange rest on the top of the cement surface?

Someone told me the top of the flange should be level with the floor surface that doesn't seem right.

Thanks for any help.
Joe

 

Bottom of flange on top of finished floor.

 

IF you haven't installed the flange yet, please do not use the all plastic one- pick one that has a SS metal ring. You'll want to anchor it with some lead anchors or maybe some Tapcons. The all plastic ones are a problem waiting to happen. Should someone bump the toilet, that small plastic slot will likely crack. And yes, all toilet flanges are designed to sit on TOP of the FINISHED floor, and to be securely fastened. Now, something like a CI flange on CI pipe in a concrete floor should be strong enough without further fastening, but that isn't what you have.

 

Usually a debate about this issue. .But I agree bottom of flange on top of finished floor. #1 below.

 

The only flange I could find at Lowes was the plastic with a 3" slip in area and my pipe is 3" so I had to put a coupler to connect the flange to pipe.

I haven't mounted the flange yet so I can change to a better one, but I did glue the coupler to the 3" pipe. If I need to cut off the coupler I only have 2 1/8 straight left to work with.

The issue I had was finding a flange to adapt to the 3" pipe the current one is the same size as the pipe3".

If I get a flange to go over the 3" pipe you have the lip or edge of the pipe to restrict flow, not that it would, I thought smooth transition was better.

 

When you have to use a 3" flange, it should NOT fit inside the drainpipe. This cuts the diameter of the pipe too much. Suggest you find a better supply house for materials and get the recommended flange.

 

I picked up an Oatey brand flange that has a stainless flange that spins on plastic and it will go over the 3" pipe, is this the one to use.

 

There ya go.

 

As far as flow and any restriction to the waste line...that's a misnomer...the maximum diameter of most toilet outlets is 2 inches...some I have seen are 2-1/4" but that all depends on the manufacturer's casting mold. The correct method is to mount the toilet flange on top of the finished floor. Below is a cutaway showing the distance between the toilet and flange...

 

If you have a floating floor in bath i dont recomend installing on floating. Shoot down a spacer for flange on concrete but leave floating able to move. Thats what all the plumbers on here are leaving out since they dont do floors. Dont pinch the floating with the flange!

 

And if it is installed in a floating floor you'll probably want to add flange supports to keep your flange in place. This video shows supports on a closet flange. And you'll notice the flange is above the floor.

 

I think you may not understand the floating floor thing.

I was expecting that your video was going to show the use of spacers to get the height right, without pinning the flooring into place.