floor flange too high

I tried to replace the 50 year old toilet in my mother's house. After installing a new American Standard complete toilet I had a leak from the floor. I replaced the wax ring again and it started leaking after 2 days. I have read everything I could find on several plumbing web sites and have realized the following. The old toilet had considerable mounds of grout under the toilet. The floor flange is above the floor by about 3/8". When I put the new toilet on I did not check see if it rocked nor did I check to see if was level. I think the grout under the original toilet was to raise it up and level the toilet. Since I don't have a few days to do a grout build up and let it dry and then mybe have to redo it ( mom needs the toilet working in a few hours at best) I started reading about a spacer. Most things I read indicted I either have to lower the pipe or raise the floor. Several people have used marble, corian, pieces of floor tile or plywood under the toilet to raise it in order to deal with the raised flange. I found a 14" x 18" cutting board at Home Depot which is made of high density polyethylene. What would you people think of making a spacer for under the toilet out of this material? I would put the toilet on the piece, tace it, make an opening for the flange then cut it with wood tools. It has at least the harness and tensile strenght of plywood. It will never rot or need to be painted or water proofed. It is anti microbal, abrasion and impact resistant. Seems like a good choice to raise the toilet then I will also level it with shims if necessary. Also what do you guys say about the Fluidmaster or Fernco non-wax toilet seals? Might use it here. Any feedback or comments would be appreciated. Currently there are one inch square ceramic floor tiles on the floor. By the way the flange is soldered to the end of the 4" drain pipe. It is not anchored to the floor. Should I put something under it so I can anchor? Any comments would be appreciated. Help me make mom happy.

Cast iron doesn't require anchoring. It's leaded not soldered. Anything other than replacing the cast iron flange with another cast flange is in my estimation is a cobbled up job.

Some of the guys like the seals you mentioned.

If you had hired a plumber to do this work, would you accept a jack knife job like a cutting board under the toilet? I think not. The right way is to get the toilet flange restng on top of the finished floor. After that, use a wax ring or a waxless seal, either work just fine when the plumbing is done properly. I my not-so-humble opinion you should contact a licensed plumber to pick up the pieces and get the jobs finished right. You will be time and money ahead by doing so, plus the peace of mind in knowing that you will have no problems. I'm a confirmed DIYer, but I know when it's time to recognize my limitations.

The best way is to reset the flange. I think your idea will work fine, and assmuming it is white and you cut it carefully, may not be an eyesore; it could be set slightly larger than the base, too and maybe finished with 1/4-round router bit. In some locales, they use a stone or synthetic plate above the floor to set a toilet per code. As I understand it, this spread the load out so if it did leak, when the floor failed, the thing would be less likely to fall through!

I had a similar problem with on old toilet and use a pice of cement board. Worked great, but I wish I had thought of the cutting-board idea. Only issue with that might be that caulk wouldn't adhere to it. Silicone might, though.

ending story of the high flange

Well, I appreciated all the responses I got. I justed wanted to let everyone know the outcome. After considering all the options I replaced the flange. There was a 4 inch lead pipe that went into a cast iron pipe in the basement. I cut the lead pipe, removed the old section and put in a PVC flange to a short piece of PVC then a rubber coupling. I bolted the flange to the floor. I measured the height. The flange was 3/8" off the floor. I turned the toilet over, put a staright edge acrosss the bottom and measured to the bottom inside the toilet. The depth was 5/8". The difference was 1/4" of space which seemed perfect for the wax seal to fill in. I tried the toilet several times without the wax seal to make sure it didn't rock. The floor was uneven but with one small shim (quarter) in the rear it was level and not rocking. I put the whole thing together and it leaked in the basement after about 15 flushes. It looked like the wax seal was leaking. I did it three more times making sure I didn't pull up on the seal after I pressed down. I used a thin seal, thick seal and one with a funnel and one without. It still leaked down the outside of the drain. I gave up. I had mom call a plumber. He came with his helper and they replaced another seal. It leaked again! The plumber was stumped. He took it apart and studied it a long time. Under the toilet, near where the wax seal seats there was two very tiny scratches that were actually cracks that were leaking water. This was a brand new American Standard toilet from Lowes. He replaced the toilet with a Vitta. He reinstalled the flange. He said you have to replace everything right into the hub in the cast iron. Is this a code requirement? So, $750 later mom has a new working toilet. I brought the defective toilet back to Lowes and got my money back.
End of story. I sure learned a lot on this one!

So did I; thanks for that report. I'm surprised at the number of defective toilets that make it into the marketplace. Water is worse than cockroaches when it comes to squeezing through tiny cracks...