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Moisture-The Root of Many Problems in Exterior Trim

How a company handles the moisture issues connected with the manufacturing process of trim products (window trim, fascia, barge boards, etc.), will determine the overall quality of the finished product when it is delivered to the job site. But equally important, it will affect how well the product performs on the home for years down the road – something your customers will be concerned with.

How wood interacts with the environment

Wood is a “hygroscopic” material.  That’s a fancy name that means it interacts with the moisture in the air around it. Wood either absorbs moisture or releases it in an effort to stay balanced with the surrounding environment. It continues to do this until it is properly sealed.

Kiln drying is not the end of the moisture problem

When wood comes out of the kiln, its moisture content has been reduced considerably – sometimes as low as 6-8% depending upon its ultimate use. However, after the kiln-drying process, wood will continue to lose or gain moisture in proportion to the humidity in the air around it.

In this respect, wood is like a sponge. You can remove all of the moisture from a sponge until you are left with a hard rectangle, but as soon as you introduce water to the sponge again, it will absorb all that it can until it is saturated. Properly coating the wood trim on all sides soon after the wood has been dried to the proper MC (moisture content) is the best guard against future deterioration.

Moisture issues with non-solid wood trim products

Fiber cement trim products

There have been many trim products introduced to the market in the last decade; one of the best known is fiber cement. While it offers certain advantages, it is not immune to problems with moisture.

  • Fiber cement may be waterproof at the fiber level. However, the finished product can absorb moisture and may degenerate in freezing temperatures.
  • I addition, moisture absorption can cause mold and mildew to form, which can be transferred to the building envelope and cause exterior structural breakdown if not corrected.

OSB-based and hardboard trim products

  • All exposed edges of these manufactured products are potential delamination areas if exposed to moisture without being properly coated. This is because of the high absorption quality of the base product.

Vinyl & cellular PVC products

  • Linear expansion of vinyl trim products is problematic due to the requirement to accommodate large movement of the plastic over the average temperature range from day to day and season to season.
  • During cold snaps in the winter vinyl and cellular PVC become very hard and in some cases even brittle and subject to breakage from impact with objects especially around high traffic areas.

Properly dried and coated, wood is still the best all-around option for exterior trim products

Wood is natural and environmentally friendly and still the favorite option of many builders. The issue that builders have had to contend with in the past with solid wood products was cupping and warping when not properly dried and/or coated or both.  These problems  have been dealt with products from Belco Forest Products.

Constant moisture checks of inbound raw material prior to milling is an essential part of managing the moisture content of our solid wood products. Inbound material in many cases is perfect but when our moisture content checks discover otherwise we use our own kilns on site at the mill to further reduce the moisture to a perfect condition.

Once the wood has reached the designed, even moisture content it is further processed with a preservative treatment and then coated with a high quality primer specifically blended for Belco and our type of wood fiber and processing equipment.

The combination of proper drying techniques, as well as utilizing an effective fiber preservative (Wolman AG), and primed on 6 sides provides the ultimate in long lasting exterior trim performance. It makes it even better that it is an all-natural, renewable solid wood product and the perfect choice for you and your customers.

At Belco Forest Products we constantly monitor and get the moisture content right  in the wood products we process every day. This constant care and monitoring ensures that our XT Trim is the most stable exterior trim in the solid wood trim market. Properly installed our XT Trim offers many years of great performance and low maintenance service to any home in any part of the country.

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