How to Choose Wood to Prevent Mold?
Created By RISC | 2 months ago
Last modified date : 2 months ago
Want to use wood in your home but worried about mold? Here’s the solution…
People who love wood can face disappointment, especially in wet weather such as the rainy season. Wood contains cellulose, starch, sugars, and lignin. These all can degrade into carbohydrates, the primary food for mold.
Mold needs moisture, a food source, and a suitable temperature. If we can adjust these variables, mold will vanish. But Thailand’s hot and humid atmosphere, particularly in the rainy season, makes it tough to control moisture. Other conditions for mold growth include oxygen, light, acidity, and the type of wood.
So how to stop mold? Let's find out…
Surface mold is a type that hasn’t yet entered the wood. Mold filaments and spores have a variety of hues. They’re usually found on moist wood or in humid settings. You can eliminate them by washing the surface or sanding the wood, taking care not to spread the spores to other locations. Always wear protective gear such as masks, gloves, and goggles to avoid direct contact with mold. Breathing it in can trigger respiratory problems and allergies.
Stain-causing mold is inside the wood, either naturally or from production. It causes discoloration and shows in spots or wider areas. You can’t eliminate this type of mold, but it doesn't weaken the wood's structural integrity.
The last type of mold is wood-decaying mold that grows on the outside or inside the wood. This mold rots wood, causing it to crumble, collapse, and snap. The wood's structural strength may be impacted by bleaching and reduced density.
Figure 1 shows mold damage to flooring.
Figure 2 show mold damage to a door.
Figure 3 shows mold damage to a wardrobe.
To avoid mold problems in your home, choose wood carefully and manage the environment:
Moisture control is critical. Outdoor areas must have adequate drainage, no standing water, and wood mustn’t touch the earth. You must use long-lasting materials and wood designed for outdoors. This wood can better resist the sun, rain, and humidity. Before using it, the wood should also be treated to protect it from mold and termites. You also must regularly clean away dirt, algae, and mildew.
Moisture control is equally crucial indoors. Make sure the environment isn’t damp. Regularly open windows and doors. Let in natural light. Use fans or dehumidifiers. Check for leaks in roofs, walls, doors, windows, pipes, air conditioners, refrigerators. And check for moisture rising from the ground. Regular cleaning is also vital to minimize dust and dirt. Always dry surfaces after cleaning.
Before buying wood, check its moisture level with detection tools or get certification from the manufacturer or supplier.
Here's how you can pick wood that won’t become food for mold:
- Wood with adhesives or binders, such as plywood, laminated wood, MDF, or particleboard, must be used with care. These materials shouldn’t be exposed to direct sunlight, rain, or placed in damp places like restrooms because they promote mold growth.
- Mold can also grow on processed wood with a high moisture level. Wood that is processed or utilized in construction should have its moisture level managed. An ideal range is 10-12%. This level helps to balance the moisture in the wood with air temperature and relative humidity, lowering wood expansion and contraction while minimizing moisture absorption from the air. Acceptable moisture content varies with the local climate. (As relative humidity rises, the equilibrium moisture content rises, and as air temperature rises, the equilibrium moisture content falls.)
Chart 1 shows the relationship between air humidity and the wood's equilibrium moisture content.
Moisture control in wood, whether through air-drying or kiln-drying, varies with the intended use. Door core wood should have a moisture level of 8-12%. Flooring wood or general indoor-use wood should have a moisture content of 12-16%. Structural wood, such as Glulam, shouldn’t have a moisture content greater than 16%. Wood should also be treated before use, such as with chemical impregnation or anti-mold treatments.
You can also choose wood alternatives. Synthetic wood alternatives, for example, have higher mold resistance, reduced water absorption, and lower moisture retention.
But wood has many benefits. It’s popular because it’s low-carbon, renewable, beautiful, and has a natural feel. But don’t only focus on mold when choosing wood. Check the source to protect habitats and avoid deforestation, both of which are crucial for natural water sources.
Story by Saritorn Amornjaruchit, Assistant Vice President of RISC
References:
TIS 497-2526, Standard for Kiln-Dried Wood Products
Forestry Research and Forest Product Management Division, Royal Forest Department. "Wood-Destroying Fungi," 2006.
ANSI A190.1-2022 Product Standard for Structural Glued Laminated Timber
Maher Zakaria Ahmed Selim. Evaluation of moisture content in wood fiber and recommendation of the best method for its determination, 2006.