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An Introduction to Window and Door Terminology

Windows and doors are some of the most important assets you have against the harsh desert climates of Mesa, AZ. While selecting quality is vital, your decision shouldn’t have to be complicated. Learning some simple windows and doors lingo will make your trip to the showroom much less of a headache.


There are so many window options: Vinyl, wood, fiberglass, composite, not to mention countless features. Are you feeling overwhelmed yet? Let’s start with some terminology. A simple knowledge of window lingo will go a long way in your search for the right windows.

  • Sash – a moveable frame that holds the glass of the window. A double-hung window is created from two moveable sashes.
  • Mull – to connect two or more windows together
  • Muntins – Small strips of wood that split the sash into (lites) smaller glass sections
  • R value – A ranking that measures the efficiency of insulation. The higher the R value, the better the insulation.
  • Flashing – A thin waterproof layer of material that keeps water out of the joints
  • U-value – A rating that determines how effective a window’s insulation is. (Windows with low U-factors have superior insulation).
  • SGHC – Solar Gain Heat Co-Efficient-This rating measures the amount of solar heat allowed to transfer from the outside to the inside of a window. (A low SHGC rating keeps the interior of your home nice and cool).


  • Aluminum – inexpensive and maintenance-free, but thermally inefficient.
  • Vinyl – Energy-efficient, inexpensive, and maintenance-free, no painted needed.
  • Fiberglass – Impervious to insects, can be painted, and have the least environmental impact. Fiberglass can be an expensive material.
  • Wood – Beautiful and energy-efficient, but also very expensive and requires significant maintenance.


Learning some helpful door lingo will help you select the best replacement door.

  • Inswing & Outswing – (I/S)-a door that opens in, while Outswing (O/S) is a door that opens out.
  • Left Hand – For an I/S door, (viewed from the outside of the house), hinges are found on the left, and for an O/S, hinges are on the right.
  • Right Hand – For an I/S door, (viewed from the outside of the house), hinges are on the right. For an O/S door, hinges are on the left.
  • Lite – a pane of glass in a door (divided lites are glass panes that are, or look divided)
  • Grille – A wooden, metal or plastic door assembly that gives the appearance of divided lites


  • Steel – Have an energy-efficient core and come fully weather-stripped and pre-primed, ready to paint. Highly resistant to shrinking, swelling and warping.
  • Fiberglass – Have great energy-saving qualities, and their high performance construction makes them resistant to dents, scratches, and extreme weather. Once painted, wood-grain technology gives them the appearance of wood.
  • Wood – Offers a warm, natural appearance, but prone to negative weather effects.

Replacing windows and doors can be a major headache, but when you choose Freelite, you will be free from pressure, hassles and regret. For over 30 years we have put YOUR Mesa window and door replacement needs first, giving you the peace-of-mind knowing that you’re in the hands of a company you can trust. Get in touch with us; we’d be delighted to add you to our family of thrilled customers!

Phone 602.233.1981
Email info@freeliteaz.com