How to Remove Lock Nuts From the Bottom of Toilets

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Two bolts hold your toilet to the flange and keep it snug against the floor. They're called flange bolts because they have an oversized head that latches onto the flange grooves, and when you screw on the nuts, the heads tighten against the flange to secure the toilet. Ideally, you can unscrew the locknuts with a wrench whenever you need to remove the toilet for repair or replacement, but conditions in a moist bathroom are seldom ideal, and the nuts are often difficult or impossible to turn.


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Know What You're Up Against

The part of the toilet flange that holds the toilet is a metal or plastic ring with two bolt tracks positioned opposite each other. The flange ring is partially hollowed out under these tracks so the heads of the flange bolts can be inserted through a large opening at one end of the track and slid to the other end. There's enough space under the track for the head to rotate freely.


When the bolts are holding the toilet, the heads are pressed against the underside of the flange track and can't move. If the bolt loosens because the floor is soggy or the ring is corroded, however, it can spin when you turn the nut. There's a way to remedy this situation without resorting to a saw, but in the end, you may have to go for the saw after all.


Try Locking Pliers, Then Cut

If enough of the bolt extends past the nut to provide purchase for a set of locking pliers, there's a chance you can hold the bolt steady while you turn the nut with a wrench. Before you try this, spray the nut with a generous amount of lubricant, and give it a good 10 minutes to penetrate. Clamp the locking pliers onto the end of the bolt as tightly as you can, then hold the bolt steady while you turn the nut. If this doesn't work, it's on to plan B, which is to cut the nut off.


If you have enough room to operate one, the fastest tool for cutting off the nut is an angle grinder, as demonstrated by Jeff Ostroff on YouTube. Be sure to wear goggles and gloves when using this tool because sparks and small shards of metal are bound to fly.

In most situations, you don't have room for an angle grinder and you have to resort to a hacksaw or a reciprocating saw with a metal cutting blade. Instead of cutting through the nut sideways, though, cut vertically through the top of the bolt and the nut all the way to the washer under the nut. Cutting this way is faster and requires less clearance, as shown by Bob's Plumbing Videos on YouTube. When the cut is complete, separate the nut with a flat-head screwdriver.


Preventing Stuck Toilet Bolts

If you can prevent your toilet bolts from getting stuck with rust, you'll never have to cut another one off. There are three easy ways to do this:

  • Make sure you install brass flange bolts with brass nuts. Brass doesn't corrode the way steel does.
  • Make sure you snap the caps onto the flange bolts as soon as you finish tightening the nut. The cap is decorative, but its main purpose is to shield the nut and bolt from rust.
  • Coat the nut and bolt with clear lacquer or clear nail polish. Lacquer shields the metal from the moist atmosphere and prevents rust. It doesn't have any binding power of its own and won't make the nut harder to remove.