Generally, when your toilet begins to leak around the wax ring that seals it to the floor, the sub floor begins to rot and weaken. Other conditions such as water leaking from a nearby pipe and pooling around the toilet can also cause toilet sub flooring damage.
Another common cause is mold. To help you easily understand what you will need to do in order to fix a rotten or damaged toilet sub floor, we have made an easy to follow guide.
Tools you will need to fix the sub flooring under your toilet:
-Spray lubricant/nut and bolt loosened
-Wax ring. Make sure it comes with new bolts and nuts if yours look rusted or corroded. The ring and hardware are standard sized for most toilets.
-Either a flange repair ring or a new piece of plywood in cases where the sub floor is rotted. Use ¾ inch plywood and an 8 ft. two by four for support.
–Circular saw or hole saw
-You may need a new flange but will not know until you take the toilet out and inspect it.
– Power drill
-Wood screws(deck screws)
-Mini hack saw
Steps to Fixing your Toilet Sub Floor
Remove the two nuts that fasten your toilet to the floor. These are located at the base of the toilet, one on each side. This can be accomplished with an adjustable wrench since they generally are not very tight. If they have rusted, you may need to use the proper size socket and a ratchet to get a better grip on the nuts. Spraying the top of the nuts with some spay lubricant such as WD40 can help if they are rusted or corroded.
Using a small pipe wrench or your crescent wrench, remove the water supply from the back of the toilet. Make sure it is shut off first!
Carefully lift the toilet from the floor. Set if out of the way.
User your putty knife to remove the wax from the old wax ring and completely remove the ring.
Inspect the flange under the wax ring. It needs to be free of corrosion and should be level. If the flooring around it is soft or rotten, it will need to be replaced instead of using a flange repair ring.
If the wood around the flange is good, you can usually get away with installing a flange repair ring. To install the flange repair ring, simply apply it directly over the existing flange.
If the wood sub floor surrounding the flange is bad, cut out the bad area with your circular saw and user the old piece as a pattern for making a new piece of plywood to replace what you cut out. Then simply screw it in place with wood screws and a drill. You will want to use ¾ inch plywood for the replacement piece.
Then you may need to cut sections off a two by four to add support for the new section underneath. You can cut up a single eight foot two by four for this purpose if you need to.
Also, if you have to replace the flange, you will have to use the mini hack saw to cut through the flange and the ABS coupling underneath. After cutting the ABS coupling through to the sewer inlet, work it loose with a flat head screwdriver.
Replace the ABS coupling, flange, ring and wax ring and remount your toilet. You need to clean the old flange with a wire brush before installing the repair ring if you are not replacing the flange.
If you are replacing the flange, you will also need to use ABS glue to install the new coupling. The wax ring will be the last thing you replace before the toilet. Ease the toilet over the new wax ring and bolt it down snug, but not too tight. Porcelain toilets can crack if you tighten them down too hard. That is it, your done.
Those are the basic steps that cover either possible scenario. As you can see, you won’t know exactly what you will need until you have removed the toilet and inspected the sub floor and flange.
In cases where there is obvious rotted wood surrounding the toilet, you may already know if the sub floor will need replaced. In that case, go ahead and get the above supplies before you start.
Otherwise, you will need to prepare to have the toilet out of commission while you take it apart and then go out to the store for parts and then finally come home and put it all back together. In some one bathroom homes, this can be a major inconvenience, so be prepared.