Exterior Wood Doors Can Be Suitable for Every Climate
New technologies help wood doors withstand harsh exposures
While historically wood doors have led the market because of their workability, strength and strong aesthetics, advancements in manufacturing technologies also can be attributed to their consistent top position. Among these innovations are new techniques for enhancing the performance of wood doors in harsh climates.
In areas subject to extreme weather, some builders and homeowners have shied away from exterior wood doors because, when left unprotected, repeated exposure to rain, sunlight, and standing water can cause problems with warping, increasing up-keep and in some cases decreasing the overall life of the door. To help prevent these problems, some wood door manufacturers now offer components that can be built into their exterior doors to help them withstand tough elements, including water or other forces of Mother Nature.
Advanced Manufacturing Technologies
Wood has been a favored building product for generations because it is a natural material. As a natural material, it can begin to show signs of aging when left unprotected to the elements. With proper care and periodic maintenance, though, homeowners can prolong the youthful appearance of their exterior wood doors. The rate at which a door ages – and the frequency of maintenance it requires – are significantly affected by the amount of exposure to sun and rain.
For exterior wood doors repeatedly exposed to rain, a new technology provides improved resistance against moisture absorption in the most susceptible area of the door – the bottom of the door’s stiles. This new option, called UltraBlock technology, combines a composite block in the bottom of the stiles, along with a moisture-resistant sealant on both ends of the bottom rail, helping to eliminate rot and reduce buckling, swelling and separation in the bottom rail and lower stile components. Because the composite blocks are finger-jointed in the core of the stiles and covered by veneers, they help prevent water infiltration without changing the outward appearance of the door.
A new option now available for exterior French doors offers superior moisture and UV protection on the entire outside of the door and the warmth and beauty of natural wood on the inside. An alternative to an expensive cladded door, WaterBarrier technology incorporates a Medium Density Overlay (MDO) and PVC glazing bead on the exterior side of the door to keep water out in the most demanding weather conditions. MDO, typically used for the rigorous applications required by traffic signs and concrete formwork, is manufactured using engineered plywood and resin treated fiber. This gives MDO an extremely durable and smooth finish that is easy to paint and can withstand continuous exposure to rain, sun, insects and other outdoor hazards.
The latest exterior wood door technologies can also help doors meet strict building code requirements. For example, a new simulated divided lite (SDL) option for French and sash doors offers the look of a true divided lite (TDL) with a single glass unit. Rather than dividing and securing multiple glass panes in place as in true divided lite doors, the bars in an SDL are permanently affixed to the exterior surface of one piece of glass. An internal shadow spacer completes the authentic look. The single glass unit allows SDL doors to meet hurricane and design-pressure requirements, and reach higher energy efficiency ratings than TDL doors.
Providing Appropriate Protection
In addition to a door type and climate, several other factors influence the maintenance requirements and longevity of a door and therefore must be considered to provide adequate protection.
Whether staining or painting, an exterior wood door should be finished before installation (prior to exposure) and done in accordance with the instructions provided by the manufacturer. In general, darker colors absorb more UV rays and more heat than lighter colors. When exposed to the sun, the exterior side of a door can reach high temperatures. If it gets too hot, finish deterioration and accelerated color fading can occur. In hot climates, light colors can help reflect the heat and reduce heat build-up. For this reason, many wood door manufacturers require customers to use light colors and avoid dark stains and paints in order to keep the door’s warranty.
If the door is being stained, the stain and sealer should have an alkyd-resin base. Under no circumstances should a lacquer-based toner or any other lacquer-based finish be used on exterior doors. The topcoat clear finish can be either oil-base or latex resin-base. Oil base clear finishes may be better for wet climates as they are more water resistant, while latex resin-base clear finishes may be better for hot climates because they have greater UV resistance.
When painting a wood door, an oil-based primer should be used first for sealing, followed by at least two topcoats of either an oil-base or latex resin-base exterior grade paint.
In either case, all six sides of the door (including the top and bottom) should be finished or the warranty may be voided. Exposure
Depending on the climate and the direction the door faces, wood doors should be installed under a protective overhang. As a rule of thumb, the overhang should project a distance from the structure equal to at least one half the distance between the bottom of the door and the bottom of the overhang. For example, if the measurement from the base of the door to the bottom of the overhang is eight feet, then the overhang should be at least four feet. In general, the greater the overhang, the better protection the door has from the elements and the longer it will last.
While storm doors do provide additional protection for exterior doors, in warm climates they may not be a wise choice. The heat that builds up between the two doors can cause damage such as warping, color fading, and wood joint separation on the wood door. If a storm door is desired, it is best to choose one that has interchangeable glass and window screen panels so that in the warmer months the glass panels can be replaced with the screen panels to prevent heat build-up.
Wood doors enable builders and homeowners to complement a wide range of architectural styles, while bringing warmth and character to a home that is unmatched by alternative materials. With advanced manufacturing techniques, proper protection and periodic maintenance, wood doors can uphold their attractiveness and last for generations in many types of climates and weather conditions.