Egress, safety glass and code: what the installed window has to meet

Some window rules are about safety, and a good installer checks them before ordering the windows.

The rules in plain language

Bedroom escape openings: The residential code generally expects every bedroom to have a window or door that opens enough for escape. A common requirement is a net clear opening of 5.7 square feet, at least 24 inches high and 20 inches wide, with the sill no more than 44 inches above the floor.
Safety glass: Glass near doors, stairs and tubs, and large low panes, generally must be tempered or laminated safety glass. The window label or a sticker usually shows it.
Fall protection: Windows with low sills above ground level may need stops or guards depending on height and code, so ask the installer to check upper-floor openings.

State code: Pennsylvania's Uniform Construction Code is the statewide building code, based on the International Code Council's model codes.
City permits: In Philadelphia, building permits go through L&I. Changes that enlarge or move an opening, or alter structure, are the kind of work that normally triggers one.
Historic review: Where the Philadelphia Historical Commission reviews street-facing windows, a code-required change in size can still need approval, so raise it early.

What happens, in what order, and what you should do.

The hidden work that keeps water and drafts out.

Narrow trinities, tight stairs and busy streets.

Brick rowhouses near the Delaware with long-owned homes.

Do I need to replace a small basement window with an egress window?

Only where the code requires one for a habitable basement room such as a bedroom. Ask L&I or your installer.

Are old rowhouse bedroom windows up to code?

Existing windows are often grandfathered, but replacing them can trigger current requirements. Ask before you order.

Does safety glass cost more?

Usually a little. Ask for it to be priced separately.