Windows 101


Windows face perhaps the most technically challenging task of any component in a home. Think about what we want from a window:

  • To see thru it.
  • To let light in.
  • To let fresh air in.

What we don’t want ...

  • We want light but not UV light.
  • We want lots of glass but also security.
  • We want it to open but when closed we don’t want air or water or heat or cold or noise to get in.

So basically we want all the benefits of having a big hole in the wall without any of the consequences of having a hole in the wall. That’s the challenge of windows.

Anatomy of a window

The IGU (insulated glazing unit) - the heart of the modern window

  • The basic IGU is 2 panes of glass with a spacer in between.
  • The interior surfaces of the glass are treated with a nearly invisible metallic coating to filter out UV light and reflect heat.
  • The glass is sealed together in a zero humidity vacuum and the chamber then filled with argon (or sometimes Krypton) gas.
  • The spacer bars are filled with a desiccant (moisture absorbing material like those little anti-moisture packets inside packages).
    • Argon and Krypton are “noble” gases which means they are chemically stable. They are non-toxic, clear, odorless, and denser than air which makes them better insulators. Krypton is denser than Argon but also more expensive.

The Sash and Frame

  • Vinyl - lowest cost
  • Wood - best insulation value but more upkeep
  • Wood-clad - low-maintenance exterior (usually vinyl or aluminum) and a temperature-transfer-resistant wood interior.
  • Aluminum - great for rainy, humid climates
  • Composite - scrap wood shavings and plastic resins can mimic the look of wood but are virtually maintenance-free.
  • Fiberglass - the strongest and most durable windows on the market. Extremely energy efficient thanks to low thermal conductivity. Can be repainted several times. Don't twist or warp like vinyl or wood.

Common Questions

  • Do I need triple glazed windows?
  • What are Acoustic Glazed windows?
  • What are Fire Rated windows?
  • Can I paint my vinyl windows?
  • Can I damage the UV coating by using the wrong window cleaning solution?
  • Are aluminum windows always going to be the worst at insulating?
  • What’s the difference between New Construction and Retrofit Replacement windows?
  • What options do I have if I want a traditional divided lite look (ie: grids or grills)?
  • Are there minimum window code requirements for certain rooms?
    • International Building Code holds that every bedroom must contain at least one egress window. It must be at least 5.7 square feet, that is at least 20 inches wide by 24 inches high, with an opening no higher than 44 inches from the floor.
    • Some regions have a maximum glazing allowance in order to preserve Title 24 Energy efficiency standards.
  • When do I need tempered glass in a window?

PHOTO CREDIT: Getty Images