Re: Toilet Lifts from Floor After Heavy Rains
My thought is it's exactly as you say. And as MSSP suggests, it's anchored to the flange but not to the floor.
If you remove the toilet, you should be able to fasten the flange on the pipe down to the floor. You'll need to replace the wax ring when you replace the toilet, so be prepared for that.
Hydraulic pressure in soil can be amazingly strong. I wouldn't be surprised if, after you fasten it down, it lifts up again and strips out the screws or bolts you put in to hold it down. If that happens, I'd suggest digging up the drain pipe and bedding it in sand (make sure you dig under the pipe, too!) so that it has some wiggle room when it rains.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.