Swap in a Comfort-Height Toilet Without a Single Leak
A 17-inch seat instead of 15 feels like a different bathroom for anyone with knees. The swap is a two-hour job if you measure the rough-in before you buy.
Standard toilets put the seat about 15 inches off the floor, a height decided a century ago for a shorter population. Comfort-height models raise that to 17 to 19 inches, the same as a dining chair, and the difference is immediate for anyone tall, anyone with bad knees, and anyone planning to stay past 65. The swap is one of the friendliest plumbing jobs in a house: one water connection, two bolts, and a seal.
Measure before you shop
The rough-in is the distance from the finished wall (not the baseboard) to the center of the closet bolts holding the current toilet down. Almost every house is 12 inches; older homes and tight bathrooms are 10 or 14. Buy a 12-inch toilet for a 10-inch rough-in and the tank hits the wall. Elongated bowls are more comfortable but stick out 2 inches farther, which matters if a door swings past.
Drain and remove the old toilet
Shut the supply valve, flush, and hold the lever until the tank empties; vacuum the rest. Disconnect the supply line, pry the caps off the closet bolts, and remove the nuts — if they are rusted solid, cut the bolts with a hacksaw. Rock the bowl to break the seal, lift straight up, and stuff a rag in the drain to block sewer gas.
Clean the flange to bare metal or plastic
Scrape every trace of old wax off the flange and floor. Old wax under a new seal is the top cause of a slow leak that shows up as a rotten subfloor two years later. The flange should sit on the finished floor or no more than 1/4 inch below it; if new tile buried it, use a flange extender. Slide new brass bolts into the slots and hold them upright with the plastic keepers.
Choose wax or waxless
A wax ring is $5, forgiving, and one-shot: lift the bowl after it compresses and you need a new ring. A waxless rubber seal costs $10 to $20, tolerates a slightly low flange, and lets you lift and reset the bowl if the shims need adjusting — smart money for a first-timer. Either way, the seal goes on the flange, not the bowl.
Set the bowl straight down, then shim
Lower the bowl over the bolts straight down — no tilting or sliding — then sit on it to compress the seal evenly. Check with a torpedo level and slide plastic shims under any low side until it does not rock; trim them flush. Only now snug the nuts, alternating sides a quarter turn at a time until the bowl is firm. Stop there. China cracks with one more turn than it needed.
Mount the tank and test
Set the tank gasket, lower the tank, and tighten the tank bolts evenly until it is level and does not shift. Thread a new braided supply line hand-tight plus a quarter turn. Open the valve slowly and flush five or six times while checking the base and tank bolts with a dry paper towel.
A bowl that rocks even slightly will grind through any seal within months. Shim it dead still before tightening, and never use the closet bolts to pull a rocking bowl flat. A cracked or corroded flange gets a repair ring before any new toilet goes on it.
Straight down, shim it still, snug it once. That is the entire secret.
Sealing and living with it
Caulk the base, leaving a 2-inch gap at the back so a future leak shows itself instead of hiding under the toilet. Check the floor around the base after the first week and again at a month. Set this way, the seal outlasts the fill valve and the flapper; when something drips years from now, it will be a $10 tank part, not the work you did today.
Keep the momentum going
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