The residential code treats certain spots in a house as hazardous locations and any glass in them has to be safety glazing. For windows that almost always means tempered glass. In a new Washington home the list is short: glass in doors, glass beside doors, large panes close to the floor, glass around tubs and showers, glass near stairs and glass in railings. Each one is triggered by a measurement. Washington builds to the International Residential Code with state amendments and the numbers here come from section R308.4 of the current IRC. Confirm them with your plans examiner before you order, since code cycles and local amendments change.
Most plans mark the tempered units. The trouble starts when the plans change after the window schedule is written and the glass stays as it was.
Glass in doors and beside them
Every pane in a door counts, whether the door swings, slides or folds. Sliding patio doors come with tempered glass as standard for that reason.
Windows next to a door are where the tape measure comes out. If the nearest edge of the glass is within 24 inches of either edge of the door in its closed position and the bottom of the glass is less than 60 inches above the floor, the pane has to be tempered. A sidelight or a narrow fixed unit beside the entry is the usual case. A wall between the door and the window takes it out of the rule and so does a pane set high enough. The code has a few more exceptions and special cases, so check a close call with your examiner.
Big panes close to the floor
A window pane counts as hazardous when all four of these are true:
- the single pane is larger than 9 square feet
- its bottom edge is less than 18 inches above the floor
- its top edge is more than 36 inches above the floor
- there is a walking surface within 36 inches of the glass, measured horizontally
It takes all four. A large picture window with an 18-inch sill doesn't need tempering and neither does a low pane under 9 square feet. Drop that same picture window to a 12-inch sill in a living room and it does. The units to look at are tall fixed windows near a stair, low glass in a great room and floor-level panes on a modern elevation.
The code allows a protective bar across the glass instead in this one case. Most builders temper the pane and skip the bar.
Around tubs, showers and pools
Glass in a wall that contains or faces a tub, shower, hot tub, sauna, steam room or pool has to be tempered when its bottom edge is less than 60 inches above the standing surface. Inside a tub or shower, the standing surface is the bottom of the tub or the shower floor. Glass more than 60 inches from the water's edge, measured horizontally, is exempt.
In a new house this usually means the bathroom window. A small obscure window high on the wall can stay standard. Move the same window down to the end of the tub and it has to be tempered.
Near stairs and landings
Glass with its bottom edge less than 36 inches above the walking surface of a stair, a landing or a ramp is hazardous. It's exempt if it sits 36 inches or more away from the walking surface horizontally or if a guard or rail protects it. The bottom landing has its own rule. Glass less than 36 inches above that landing and within 60 inches of the bottom tread nosing also has to be tempered.
Stair windows are the ones most often missed. They show up on a section or an elevation, a different sheet from the window schedule and a tall fixed unit on a stair wall can end up a few inches from the treads without anyone noticing until inspection.
In railings and guards
Glass that forms part of a guard or railing is always safety glazing, whatever its size or height. It rarely comes up in a window order, but it does with glass balcony panels.
What the inspector looks for
Tempered glass carries a permanent mark in one corner, etched, fired or sandblasted into the pane. The code requires that mark on every pane in a hazardous location and requires it to stay visible after installation. Inspectors look for it and a tempered pane with the mark hidden under trim can cost you a second visit.
Both panes of a double-pane unit in a hazardous location have to be tempered. Tempered glass also can't be cut or drilled once it's made, so nothing can be fixed on site. A missing tempered pane means a new unit and the wait that comes with it.
Catch it on the schedule
The cheapest place to fix tempered glass is the window schedule, before the order goes in. Go through every opening and ask four questions: is it in or beside a door, is it big and low, is it near water and is it near a stair? Mark the tempered units on the current plans rather than the first version of the schedule. Then count them on every quote you get. A quote with fewer tempered units than your count is cheaper for a reason you'll pay for at inspection. How to compare window quotes covers the rest of that check and the egress article covers the other code number bedroom windows have to meet.
How we handle it
Our quotes mark every tempered unit on its own line, so you can count them against your plans. When we quote from a full plan set we check it for tempered locations too and we flag any that look missed before you order. Send your window schedule and we'll go through it.