Impact Windows and Doors
Impact Windows and Doors 101
Impact windows and doors consist of impact-resistant glass surrounded by a heavy-duty frame, which is securely fastened to the interior window header and frame. This construction and anchoring keep high hurricane winds and debris from breaching your home.
Impact-resistant windows and doors look like traditional glazing, but they are multi-layered, with stronger, heavier frames than traditional windows.
The idea for shatter-resistant glass windows for homes came from the automotive field where laminated glass has been in use for years to protect occupants. There are two common types of impact-resistant glazing for your windows:
- Laminated glass consisting of two sheets of glass with an inner shatterproof membrane between them. These windows are designed to handle wind-borne debris hurled at high wind speeds and repeated impact from would-be intruders.
- Window film applied to the surface of the glazing. With filmed windows, shatter-resistant film is placed over the glass to keep the window shards in place if broken. Their durability really depends on how well the glass and protective laminate stay in the frame and window assembly.
Protecting Your Home Envelope
Impact windows and doors protect your home from wind and water damage in hurricanes. A broken window provides a point of entry for wind that enters the house, increases pressure, and seeks another way out. The only way to protect against damage from wind entry is to keep it out. This means deflecting wind and driving it around the building. This is why hurricane measures have been enacted in Florida for new building in hurricane zones. Residents must install impact resistant windows and doors or a permanent shutter system.
Frames Add Strength to Glazing
It takes an entire window system to make an impact-resistant opening. Frames for impact-resistant windows or doors may be constructed from wood, metal, vinyl, or any combination thereof.
Missile Testing For Total Security
Not every window on the market can claim to be impact resistant. There are testing standards set forth by the American Society for Testing & Materials (ASTM) that must be met before the window is certified as being impact-resistant. One of the most stringent of the requirements comes from the South Florida Building Code, which has been concerned about the increase in the number and force of hurricanes over the years.
According to the code, windows and doors must meet requirements for large and small missiles. It specifies that for large missiles, the window has been tested with an impact from a six-foot long 2 by 4 weighing nine pounds, traveling at 50 feet per second. The test is done in a laboratory setting with the lumber fired from a cannon into the window. The window glazing must remain intact after the impact.