Water Heater Seismic Straps:
Missing, Loose, in the Wrong Place or Anchored to Nothing
A full 50-gallon tank weighs about as much as a refrigerator and sits on a small base. In an earthquake, two metal straps are what keep it standing.
Twenty-two water heaters in Russ’s recent reports had no seismic straps at all. Others had straps in the wrong spot, a single metal band draped over the top in Portland, or straps screwed into loose wood blocking in Beaverton. Across 269 houses, about 28 had a water heater strapping finding.
The Portland metro sits in earthquake country. A water heater is one of the few things in the house that can turn a moderate shake into a gas leak.
Why water heaters get strapped
A standard 50-gallon tank holds about 400 pounds of water, and it stands on a base the size of a dinner plate. In an earthquake it rocks. Without anything holding it, it can walk off its stand or tip over.
When a gas water heater moves, it pulls on its gas line and its vent. A gas connector can break or pull apart. The vent can come loose and spill exhaust into the house. Water lines tear and the tank empties onto the floor. The post on Portland’s seismic risk covers the bigger picture.
Where the straps go
The plumbing codes used in Oregon and Washington call for two straps:
- One in the upper third of the tank
- One in the lower third, staying at least 4 inches above the controls on a gas unit
Each strap wraps around the tank and anchors to solid framing or the masonry wall behind it. Most kits use heavy steel bands with a bolt or lag screw at each end, and some use a spacer when the tank sits away from the wall.
In Sandy, Russ’s report noted that modern safety standards call for a strap in each third. In a Portland house, the straps were on the tank but outside those zones.
Real Inspection Photos
Water Heater Strap Findings From Russ's Inspections
Missing and improperly anchored water heater straps from Russ's recent reports.
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A strap anchored to loose wood blocking instead of the framing or the concrete wall. -
A cargo-style strap around the tank in place of proper seismic straps. -
A gas water heater with no seismic strap. -
No seismic straps on this closet water heater. -
A metal band over the top of the tank, which doesn't hold it against sideways movement.
What Russ finds instead
No straps was the common one, in Vancouver, Sandy and many others. After that, the variations:
- A metal band draped over the top of the tank in Portland, which holds nothing sideways
- Straps anchored to stacked, loose wood blocking in Beaverton instead of framing or concrete
One common way a house ends up with no straps: the water heater gets replaced and the straps don’t get put back on the new tank.
Other things to check while you’re there
Straps are one part of a safe water heater install. The relief valve discharge pipe post covers the safety valve. The backdrafting post covers the vent on a gas unit. A flexible gas connector rated for the job lets the tank move a little without breaking the gas line; the post on uncoated brass gas connectors covers the older ones that shouldn’t still be in service.
What Russ checks
He looks for two straps, checks their position on the tank and how they’re anchored, and looks at the gas connector, vent, relief valve and pipe, and the base the tank sits on. He reads the data plate for the approximate age; the water heater label post explains that. Missing or improper straps go to a licensed plumber or a qualified handyman.
- Count the straps: there should be two
- Check one is in the top third of the tank and one is in the bottom third
- Make sure the lower strap clears the controls on a gas unit
- Follow each strap end to a stud or the concrete wall, not drywall or a block of wood
- Push on the tank gently; it shouldn’t rock
Two straps, upper third and lower third, anchored into framing or masonry. Missing straps were the most common water heater safety finding in Russ’s reports after relief valve problems. A strap kit is an inexpensive fix.
For the rest of the plumbing, the guide to what to look at in the plumbing before you make an offer covers pipes, drains and fixtures. To set up an inspection, you can book online.
Water Heater Strap FAQ
