Subject: RV Floor Repair after Toilet Water Supply Leak
Date: March, 2010
PROBLEM: The toilet was not firm on the floor. I removed the
toilet from the floor and found the flange gasket intact but the floor
rotted around the toilet flange. When removing the toilet, I found the
water supply fitting was loose at the toilet. This allowed water to run
down the supply line, drip onto the floor, and run unseen over the edge
of the vinyl into the flange area of the floor.
Before starting repairs, I did some Internet research and decided on
the Rot Doctor CPES product. This turned out to be a good choice
because of the product itself AND the email help I got from Dr. Rot.
Following are the steps I took in the repair, with photos for each step:
Click on photos to see larger.
Step One: Removed Toilet and Assessed Damage
Here the toilet and flange are removed. In our case the flange unscrews
on its 3” female thread. Floor is 7/16” Opposing Strand Board (common
roofing called OSB). Roughly a square foot of the floor is rotted. The
worst areas look like damp coffee grounds. The coach has a sheet metal
bottom under the flooring and there are a couple inches of Styrofoam
insulation between. In this picture, I’ve used a “hook blade” in the
utility knife and have cut the vinyl floor covering away from the
flange area. The footprint of the toilet itself was the pattern for
this cut. Thetford sells a “pedestal” which raises RV toilets to home
toilet height. The pedestal has a much larger footprint than a toilet,
and the faint line on the flooring is the footprint of the
pedestal. The dark line is an inch in from the pedestal
footprint. I cut the floor covering out along that line.
Between Steps One and Two, I dug out the worst of the rotted OSB until
I reached “punky” (spongy) or better material. Tools were a pocket
knife and a vacuum cleaner. I laid out the holding tank inlet on a
cardboard template and cut the template to fit the space where rotted
OSB was removed.
Step Two: Cut New OSB Repair Patch from Template
In this photo, the patch is in place with the flange and pedestal
bolts. The cardboard template is shown (and the Winegard WingMan
antenna add-on which works very well for DTV, by the way). I’ve cut the
floor covering away from the wall behind the toilet and the vanity
beside the toilet to gain better access to the damage. I also made a
cut near the far rear corner to be able to lift the vinyl out of the
Step Three: Applied Rot Doctor CPES
I bought the Warm Weather Two-Pint Unit #101 and mixed several small
batches for each application. I dedicated one small jar (about
1-1/2 ounce) to Part A and an identical one to Part B, and kept them
separate through all applications. The new OSB patch required two
applications before it wouldn’t take any more. The damaged area
required four applications and used twice as much CPES even though the
surface area was much less. This shows how CPES penetrates and fills
Step Four: CPES Application Complete
Here you can see how the patch appears shiny. I added aluminum tabs to
the bottom side so the stainless steel flange mounting screws have
metal to bite into and not just OSB. The damaged wood got firm but not
“new wood hard.” I’m confident that rot was arrested and adequate
strength restored. Notice that a hole appeared between the two cans.
It’s not in an area that anybody can stand on, so I decided to only
span it with a small piece of sheet aluminum.
Step Five: Patch in Place, Ready to Reinstall Floor Covering
I put the patch down and tightened the flange firmly into place. I used
a carpenter’s square to lay out the mounting holes so the toilet would
go back in place straight.
Step Six: Flooring Reinstalled
I used prefinished quarter round molding and predrilled it for drywall
screws. I removed the aluminum piece showing here since it kept
the pedestal from resting flat on the floor. The white line in the
upper right is bathtub sealant covering the one visible cut in the
Step Seven: Pedestal Installed – Yes, I removed the Rag!
Step Eight: Toilet Installed – Project Complete!