Ask the Builder: Got a toilet leaner in your household? Install shims between tank and wall

Q. An unnamed person (rhymes with “house”) living in my home says the toilet seat lid and toilet tank are made for leaning back against while using the fixture for personal needs. In a negotiation debate with this person, I mentioned the bolts fastening the tank to the bowl aren’t strong enough for leaning as one might against a standard chair. What say you, wise Tim? Do you arbitrate these touchy discords between cohabitants on a frequent basis? – Donn R., Shelby Township, Michigan

A. I live in New Hampshire, and mice are as common indoors in the winter as snow is outdoors. That said, I’ve never known one to be able to use a toilet. Oh, wait, Donn isn’t talking about a mouse! Truth be told, I adjudicate disputes – or should I say spirited discussions? – between two people living under the same roof at least once a month.

I’ve installed more toilets than I care to remember. The traditional toilet tank used to have just two brass bolts that connected it to the toilet bowl. One manufacturer years ago thought this was insufficient and developed a three-bolt design. The third bolt added lots of strength.

The bolts in either design are plenty strong and should never break if someone leans back against the tank while sitting on the toilet bowl. However, it’s the rubber O-rings that surround the bolts that are the issue. It’s entirely possible to create a leak between the toilet tank and bowl if you push back against the tank too much.

This is quite possible as the toilet ages and the rubber O-rings become less pliable. I’m sure you’ve seen rubber that becomes brittle with age. You don’t want to hope the rubber O-rings stay supple indefinitely. You hope for things you can’t control like the weather or when a volcano might erupt.

Plumbers can install toilets so the tank is snug against a wall, but this requires quite a bit of planning. What’s more, if the tank is tight against the wall, the tank lid might not fit well because the lids are larger than the tank and often have an overhanging rear lip.

It’s easy to keep peace in these situations. When the leaning cohabitant is out and about having coffee with a friend or picking up groceries, you can glue wood shims between the back of the toilet tank and the wall behind the tank.

You can use paint-stirring sticks, regular tapered wood shims and construction adhesive that comes in a standard caulk tube to accomplish this simple fix. The key thing to remember is to be sure the shims are about 1/2-inch below the top of the tank lip so the tank lid doesn’t touch the shims when you put it back on.