Lately, I’ve been receiving questions regarding locations and sizes of lite cutouts in wood doors. What is acceptable?
The issue goes beyond aesthetics, although that certainly plays into much of the decision from a design perspective. First, there is a concern with safety. Vision lites allow those exiting to see a person on the opposite side of the door and prevent hitting that person with the door, as well as allowing one seeking entrance to avoid being struck by the door. Full-lite, half-lite or narrow lite doors will help with providing the sight lines necessary to allow for safe operation of the door.
Second, there is a concern with accessibility. Vision lites need to be low enough (when provided) to allow a person in a wheelchair to see through the door. The 2010 ADA Standards says that the lowest point of a vision light in a door or sidelite shall not be above 43″ above the finished floor, unless the vision light is greater than 66″ above the finished floor. In that case the vision lite is exempt.
When using glass in wood doors, there is the additional concern of structure of the door, and the impact of placement and size of the glass cutout in relation to any hardware preparation in the door. Having less than six inches between vision lite cutouts and hardware preps (or the door edge itself) will void warranties on most particleboard core commercial doors. Oshkosh has a handy calculator for determining size and location of lite cutouts which will return whether your elevation is “Okay!” or in “Conflict!” The calculator can be found at this jump. You simply need to enter your lite kit size, hardware location and stile and rail margins.
If your design calls for a full glass cutout, small midrails or more than 40% of the door face cutout for glass then you should use a Structural Composite Lumber (SCL) core. This is a material made of strips of wood layered together to form billets of the size and thickness required. Due to the increased strength of SCL, you can have warranties on doors with more glass and smaller stiles and rails than possible with particleboard. This material also does not accept moisture as quickly as particleboard, nor does it swell as much, so this is an appropriate core to use in high-humidity applications. Here is a brief summary of the advantages of SCL: GT Series Core Advantages.
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Doors & Door Hardware 