Do You Need a Building Permit for a Bay Window?

One-for-one window replacement doesn’t usually require a building permit. But what about a bay window? After all, installing a bay window is a more involved process than installing a regular window. Would this trigger the need for a building permit?

Short Answer

Most likely, no, you do not need to obtain a permit to replace an existing window with a bay window.

Details

Generally, a one-for-one window replacement does not require a building permit. But when you start to increase your house’s footprint or alter the structure itself, building codes begin to apply. A typical local code provision will read something like this:

Permits shall not be required for the following: In-kind window replacement for IRC structures where no alteration of structural members is required and when the window U-values meet the current prescriptive requirements of the International Energy Conservation Code.

A few things to keep in mind, though:

• Because bay windows do not open, they are not a means of egress in the event of fire. Make certain that installing the bay window does not close off a required means of egress.
• Though a bay window does not rest on the ground (like a room addition might), it does decrease the distance from your house to the house next door.
• You might need special tempered glass for the bay window. Because some bay windows have seats that permit both sitting and (often with children) standing, this stronger tempered glass may be required to prevent people from accidentally falling through.