I have a toilet on the second floor that keeps leaking around the bottom of the toilet. I have replaced the wax ring and putty around the bottom of the toilet, unfortunately the floor is a little rotted from the leaking and the bolts that held the toilet to the floor no longer hold so the toilet doesn't stay very sturdy. It has started leaking again and I think this is why. At some point we probably want to replace the floor but that is way down the road, for now we just want to fix it so it won't leak, regardless of how it looks. I'm thinking about putting a piece of wood about 2 ft by 1 and 1/2 ft and about a 1/4 inch thick down, cutting a hole around the current pipe hole and bolting the toilet to the wood, then drilling the wood to the bathroom floor. My concern is the toilet holding to the wood, and drilling the wood to the floor of the bathroom, right now it is just linoleum and again, we are not concerned at all how it looks. Are there any pipes or electrical work that I should worry about, or any way to tell where they are to drill around? Is there a better way to keep a toilet sturdy to a semi rotted floor. Any other concerns or advice would be greatly appreciated. Thanks.

Why are you not just going to pull up the flooring around the toilet and take your plywood and cut it to size and fit it in.

You need to see what other damage is being done to the floor.

I agree with Fr_Chuck, fix the floor properly. It will only get worse and start smelling and growing mold. If your toilet is actually screwed into the wood it probably was never installed correctly to begin with. How To Replace or Install a Toilet - The Home Depot - YouTube

Thanks Guys, this helps. The toilet definetely wasn't installed correctly, after watching the video I see that we don't even have the toilet flange in the floor that bolts to the toilet. Unfortunately I'm not sure if I am able to replace the whole floor, that may be out of my ability range. Maybe just cutting out a section around the toilet to put the new plywood and making sure there is a flange this time will be sufficient, hope it's not over my head...

Does your toilet tie down with a closet flange or wood screw closet bolts? Back to you, Tom

Currently it looks like it was just bolted directly into the wood floor. There are holes next to the pipe in the wood but there is no way they are holding the toilet down anymore.