Care for wooden decking

Wooden terraces are a luxurious and representative type of flooring. To ensure your wooden terrace looks its best, it is essential to choose a proper design and pay attention to regular maintenance. Prevent the accumulation of coarse dirt and avoid mechanical damage to the wood. Protect chairs, tables, and other furniture with pads to prevent dents and scratches on the terrace. Regularly clean the terrace from dirt, soil, debris, and pollen. This prevents contaminants from penetrating the pores of the wood.

Under objects placed on the terrace, such as umbrella stands, flower pots, trays, or mats, water and moisture can accumulate. This prevents the wood from drying naturally and quickly, and under these objects, stains may form from prolonged moisture and dirt. Therefore, occasionally move objects or ensure natural drying and air circulation beneath them. This prevents the formation of dark stains on the wood.

Wood that can dry quickly after getting wet lasts longer than wood that remains damp. Keep terrace boards free from fallen leaves, pine needles, and other debris that can retain water and moisture. This allows the wood to dry properly. Organic debris, such as leaves, seeds, or other matter, can clog the gaps between boards, creating puddles and softening the organic deposits, which may release tannins that can stain the floor. These organic deposits are a strong nutrient source for mold. Keeping the terrace surface free of debris is the easiest way to maintain a clean floor.

If the gaps between boards start to clog, remove debris using a garden hose, spatula, squeegee, or a similar tool. This helps preserve the longevity of the flooring. For scattered organic material, such as leaves, it is better to use an electric garden blower or broom. Remove accumulated dirt with a broom. Experienced professionals may use a low-pressure washer below 1,500 psi (10.3 MPa) at a safe distance of at least 30 cm above the terrace surface. In inexperienced hands, this may damage the terrace. Be extremely careful when using a pressure washer.

Wood Surface Treatment

Wood species intended for outdoor use according to their durability class may not require chemical surface treatment. However, it is generally recommended to protect the wood with an appropriate surface finish. Treating the wood prolongs its lifespan, slows down the weathering process, and improves surface quality.

Factors Affecting the Durability of Wood Finishes

The durability of a wood finish is influenced by many factors. On horizontal surfaces, the finish lasts for a shorter time and weathers faster than on vertical surfaces or in covered or otherwise protected areas. Coatings slow down the natural weathering process of wood but never completely stop it. When applying coatings to new wood, the durability of the finish is lower compared to coating old wood. New wood contains natural extractives and has a higher density, which partially limits the penetration of the coating deep into the wood. Generally, old wood shows longer durability of coatings due to deeper absorption of oils into the wood.

For this reason, it is recommended to apply oil-based coatings on new, especially exotic, wood no earlier than one month after exposure to weather, and water-based coatings after three months, once the extractives have been released. Lower durability of coatings can also be observed in terrace projects installed at ground level without sufficient side ventilation. Expansion gaps between boards in this case do not provide adequate airflow. Under such terraces, high ground moisture can occur, increasing the wood’s moisture content, causing crosswise bending, wood expansion, and preventing proper saturation of the coatings. This leads to the oil being pushed out of the wood and rapid flaking of the finish.

On coated surfaces, uneven weathering or flaking may also occur due to uneven application of the coating, i.e., thinner layers compared to areas with a thicker layer of oil. This can also happen in areas exposed to greater amounts of UV radiation, water, snow, reflected sunlight from glass surfaces, areas affected by automatic irrigation systems, the use of de-icing salt in winter, increased mechanical wear, and other influences. This phenomenon also occurs in areas that are covered or otherwise protected compared to surfaces exposed to weather, resulting in uneven flaking of the coating. Weathering occurs significantly faster on south- and west-facing surfaces compared to east- and north-facing surfaces.

Wood Splintering

If wood is left untreated, weathering or exposure to the elements reduces surface smoothness and increases the likelihood of raised wood fibers and splinter formation. To increase surface smoothness on both new and old wood, sand the terrace surface with an electric sander. Treating the wood with an appropriate finish significantly reduces the risk of splinter formation and improves the surface quality. The basic structural component of wood is cellulose fibers, so the presence of splinters in wood exposed to climatic influences is completely natural.

Characteristic Properties of Wood

If you decide on a terrace made of natural wood, it is necessary to accept its inherent physical and characteristic properties. Wood exposed to outdoor climatic conditions must adapt to many factors. High temperatures, frost, rain, sunlight, and other climatic influences affect the character of the wood and change its appearance. Wood naturally reacts to climatic, humidity, and temperature changes in the environment in which it is located. Due to the constantly changing relative humidity of the air and climatic changes in the outdoor environment, it is impossible to prevent dimensional changes in the wood, the formation of drying cracks, or other natural changes such as variations in board width and length, warping, crosswise bending, and the weathering process. These characteristics occur in all types of wood and cannot be considered defects.

Formation of Drying Cracks

Wood is a hygroscopic material that reacts throughout its lifetime to environmental temperature changes and, in particular, to fluctuations in relative humidity of the air or surrounding environment. Wood adapts to changes in environmental moisture. At high relative humidity, the wood absorbs moisture and expands, while under low humidity conditions, it dries and shrinks. These dimensional changes in wood cause the formation of surface and end drying cracks. End cracks are most pronounced at the ends, where the wood fibers absorb moisture and dry up to 200 times faster than other areas. However, it is entirely normal for drying cracks to also appear irregularly across the surface due to anisotropic shrinkage. Anisotropic shrinkage is a natural property of wood, where shrinkage occurs in different directions (radial, tangential, and longitudinal) depending on the growth direction of the fibers. The formation of drying cracks, as well as changes in width, crosswise bending, and deformation, are common phenomena and a natural response of wood to climatic fluctuations; they do not constitute a manufacturing or material defect.

Small Holes from Wood-Boring Insects (“Pin Holes”)

Living trees often contain insects that are commonly found under the bark, in the sapwood, and occasionally in the heartwood. These insects cannot survive industrial wood processing, drying, or fumigation. However, traces of their activity may remain in the form of very small holes, approximately 0.5–2 mm in size, known as “pin holes.” The potential presence of these small holes caused by insect activity is noted in the product technical sheet, and their occurrence is not considered a defect.

Color Variations

Wood is a completely unique and natural material, inimitable in its structure, color, and fiber growth. Different color shades between individual pieces are allowed without limitation and are not considered defects. Color variations are most commonly caused by the differing ages of tree trunks. Especially in tropical wood species, significant color differences are entirely normal. Over time, exposure to UV radiation and climatic influences leads to color uniformity and further weathering.

Knots and Other Natural Wood Features

Knots and burls, whether healthy or partially grown together, cracks around knots, pith flecks, resin canals, marbling, and other natural features are an integral part of wood. Although tropical wood species generally have a low number of knots, the number and occurrence of the features mentioned above are allowed without limitation.

Sticker Marks

Wooden terraces and beams are often stacked with wooden spacers during storage to ensure ventilation and increased stability of the bundles. As a result, colored marks may appear on the surface of the wood, known as “sticker marks.” The presence of these marks on the wood surface is not considered a defect and is allowed. Over time, exposure to sunlight, weathering, and color changes will cause these marks to disappear. They can also be removed by sanding the surface with an electric sander. For the best appearance, it is recommended to sand the terrace surface after installation to remove any dirt, handling marks, and to generally improve the quality of the wood surface.

Oil and Grease Stains

The best way to remove oil and grease stains is to clean them quickly. The longer oil or grease remains on the surface, the more likely it will penetrate the wood fibers, making cleaning very difficult. The amount of time depends on the type of stain, exposure to water and sunlight, and other factors. To remove oil or grease stains that cannot be cleaned with soap and water, use a cleaner or another commercial product suitable for your type of flooring. Follow the manufacturer’s instructions and test the product on an inconspicuous area before cleaning the entire floor. Place a protective mat under a grill to help protect your floor from grease stains.

Mold

Mold is a common form of life in our environment. Mold grows on decaying organic materials such as fallen leaves and pollen. Tiny, lightweight mold spores travel easily through the air, and varying climates with changing temperatures, humidity, and sources of organic nutrients create conditions for mold survival. A wide range of building materials, including concrete, wood products, vinyl boards, and many others, can become potential sites for mold growth. To minimize mold growth on your terrace, clean it as often as necessary, at least twice a year. It is important to remove leaves, dirt, and other organic materials that provide a food source for mold. Many commercial products are available for cleaning and removing mold. Follow the manufacturer’s instructions and use cleaners within their recommended shelf life. Do not mix cleaning products, as this could cause harmful chemical reactions. Never use bleach or acids.

Tannin Stains

Tannins (natural dyes and resins) are naturally present in all types of wood and sometimes migrate to the surface where the wood fibers are exposed to sunlight and water. Tannin stains dissolve naturally over time through the action of rain and water. Depending on the season, this may take several weeks to several months. To accelerate the removal of tannin stains, a wood cleaner and brightener or other commercial products suitable for your type of flooring can be used. Follow the manufacturer’s instructions and test the product on an inconspicuous area before cleaning the entire floor.

Moss and Green Coating Formation

The growth of moss and green coatings occurs wherever conditions are suitable for their development, particularly in areas exposed to prolonged moisture without the opportunity to dry or clean. Moss growth can be observed not only on organic materials but also on other surfaces such as stone or concrete. Removal is possible through regular maintenance and the use of products that inhibit moss growth, for example, Saicos green remover.

Wood-Destroying Fungi and Rot

The presence of wood-destroying fungi and the associated rot can occur under conditions that provide a suitable environment for their growth. Fungi require these conditions to develop, and the mycelium grows when the wood remains in a consistently damp environment. Wood rot occurs because fungal hyphae secrete enzymes that break down the cell walls of the wood, converting cellulose, hemicellulose, and lignin into soluble sugars, which the fungus consumes. Fungi reproduce via spores and mycelium. For wood-destroying fungi to grow, these conditions must persist over time. To reduce the risk of fungal growth, it is recommended to design terraces so that adequate space for air ventilation and drying is provided underneath. The terrace should be elevated above the surrounding terrain, ensuring free drainage so that water or high humidity does not remain trapped under the boards or decking. Retained high moisture under the terrace could result in cupping, deformation, reduced wood lifespan, and increased risk of mold, rot, or fungal infestation.

Natural Coloring - Bleading

Tropical wood species produce natural resinous compounds called tannins during growth, which act as protective agents, ensuring durability and resistance to wood-destroying fungi. When exposed to weather, tannins are released by rain or high humidity in the form of a brown liquid. This is a natural process, and the time it takes for the pigment to wash out depends on the level of exposure to weather and rainfall. For wood exposed to direct weather, the tannin release process usually lasts months, depending on the frequency and intensity of rain. Take care to prevent the natural pigments released during rain from staining surfaces beneath or around the wood. Ensure proper rainwater drainage via gutters. If staining occurs or quick removal of natural pigment is needed, effective cleaning can be done using Saicos wood brightener and cleaner or a solution of Sava and water in a 50/50 ratio. Follow the manufacturer’s instructions and test on an inconspicuous area first.

Wood Graying and Weathering – Causes and Renovation

Wood exposed to weather, particularly sunlight and rain, gradually undergoes changes in color and surface structure. In areas with sufficient drying and ventilation, wood typically develops a silvery-gray hue over several months, depending on sun and rain exposure. Wood exposed to high moisture will weather into darker, often blotchy tones. Partially or fully protected areas, such as under roof overhangs, will weather unevenly compared to open, uncovered areas. Weathering is a natural process involving the breakdown of the wood’s outer layer, lignin, and cellulose due to environmental and UV exposure. These effects occur in all wood types, with darker woods showing signs more quickly than lighter ones. The thin grayed layer can be removed mechanically by sanding or chemically with a specialized wood brightener. Other typical signs of weathering include end checks, shrinkage or swelling, rough surface texture, and shedding of spring growth layers. Chemical brighteners are effective only before weathering penetrates deeply, usually within 2–3 years depending on the wood type. Beyond that, sanding or leaving the wood with its weathered patina may be the only restoration option.

Wood Maceration

Maceration is a form of weathering that occurs in untreated wood under specific conditions, such as exposure to acidic or alkaline environments, snow or ice melt, or prolonged waterlogging, especially on horizontal surfaces. It is characterized by the release of fine, weathered cellulose fibers from the wood surface and the appearance of soft tufts resembling mold. Maceration can occur in all wood types due to weather exposure, which causes surface breakdown of lignin and cellulose, resulting in changes in color and surface structure. The solution is to lightly sand the wood surface with fine sandpaper and apply an oil layer as part of regular maintenance.

Causes of Wood Blackening

Blackening of wood occurs more frequently on horizontal surfaces exposed to weather, where moisture, dust particles, and other debris tend to accumulate. The blackening is caused by the gradual penetration of moisture and dirt into the wood’s macropores. Over time, dust particles can penetrate even protective coatings, resulting in dark discoloration. Blackening also occurs in areas where natural drying is prevented, such as under flower pots, umbrella stands, or other objects that obstruct airflow.

Removal of blackening can be done using a mild oxalic acid solution, a commercial wood brightener such as Saicos Wood Grey Remover, or mechanically by sanding the surface.

Wooden terraces are a beautiful and representative type of outdoor flooring. To maintain their condition and appearance over the years, it is essential to care for the surface regularly. Wood exposed to outdoor conditions naturally ages, and dust, debris, and other contaminants can change its appearance. Regularly clean your terrace from dirt, soil, sediment, and pollen to prevent these substances from penetrating the wood’s macropores. On lighter wood species, the effects of dirt are more visible.

Under objects placed on the terrace, such as umbrella stands, flower pots, trays, or mats, water and moisture can accumulate, preventing natural drying. This can lead to dark stains caused by long-term moisture and dirt. Occasionally move these objects or ensure adequate airflow underneath them to avoid dark spots.

Avoid Contact with Corrosive Metals

Most wood species develop blue-black stains when in contact with corrosive metals. These stains are difficult to remove. Therefore, avoid contact between corrosive metals and wood. Use only stainless steel fasteners for installation. Also avoid metal dust or shavings from cutting or grinding near your terrace, as metal particles combined with moisture can create blue-black stains on the wood. Frequent causes include using inappropriate fasteners or metal dust from nearby metalwork settling on the wood surface. Attempting to remove corrosion stains chemically is usually ineffective, and sanding the wood surface may be necessary. Protective wood coatings do not prevent the formation of corrosion stains.

Removal of Weathered Surfaces or Blackening Caused by dirt using a chemical wood brightener is effective only until weathering penetrates deeply into the wood. The effective period for removing weathered surfaces with chemical brighteners is typically 2–3 years, depending on the wood species. After this period, sanding the wood surface is usually the recommended restoration method.