Recommended Types of Wood

Sioo:x on different types of wood

SiOO:X is a silicon treatment that protects the wood and penetrates the fiber of the wood. After treatment, wood-protective structures are formed inside the wood, which builds up a physical barrier against microorganisms. We call this “silicon shield”, based on potassium silicate that has a mechanical principle of action.


But the feature also causes the newly treated timber to change its appearance from initial yellow to beautifully light gray – a color change welcomed by many homeowners.


On the treated wooden surfaces, a maturation process occurs, and a silicon shield develops. However, how long the process takes and what the color development looks like over time depends strongly on the wood species and the conditions outdoors.


Spruce is one of our most used woods and therefore an economical and well-functioning choice in many construction projects. Spruce has a “closed” cell structure when dried which is important for paneling. The wood is characterized by small twigs and a certain softness. In untreated form, the wood species is not resistant to rot.


Spruce is advantageously used as a panel, upholstery for buildings and construction timber, but not as an outdoor deck (patio, stairs).


When choosing spruce as a wood species, the following should be considered for the best SiOO:X treatment


  • The panel profile should be of a standing type. If lying panel is selected, it should be the façade for the best water run-off, and the beveling should be thoroughly taken care of during the SiOO:X application
  • The surface must be so-called finely sawn or brushed. This allows the liquids to penetrate better with the correct and enough amount
  • If planed surfaces cannot be avoided to use, they must first be roughened up. Make sure that SiOO:X-treat thoroughly with the recommended application amount
  • SiOO:X Premium Wood Protection Panel and SiOO:X Premium Surface Protection Panel are recommended products on spruce panel. Also, SiOO:X Wood protective Panel colors with gray pigmentation in six shades work well on spruce

Pine / Heart pine

Pine timber is of great economic importance and is another type of wood that is harvested in large quantities. Pine is one of our most widely used types of wood in most constructions and constructions of wood.


The density of pine can vary from stem to top, from the heartwood to the sapwood. The pine core differs markedly from the sapwood, not only by its dark reddish-brown color, but also in many other properties such as resistance and natural rooting protection.


Ordinary untreated pine has disadvantages if used as a panel or decking. If pine is selected as a decking material, it should be pressure impregnated in class NTR/AB. As panel material in commercial sorting, we consider the pine to be sensitive, as it often contains high proportions of so-called sapwood, which is sensitive to organic infestations.


On the other hand, the heart of pine is ideally suited as a basic material for deck boards and paneling. The dense wood found in the center of a log (or tree trunk) is called the heart wood. This part is naturally resistant to rot and stands out better against organic infestations.


A SiOO:X treatment on the heart wood of pine gives good results. However, keep the following in mind when using heart pine as a decking:


  • With a high proportion of the heart in pine, you should wait 1 year before applying Sioo’s products to the surface. If you buy pre-treated timber from us, you do not have to think about that.
  • With advantage, larger coarser dimensions are used, e.g., 34x145mm (for better appearance and characteristics)
  • If you cut or process finished SiOO:X treated heart pine, these cutting surfaces should be re-treated
  • Ensure that good ventilation is achieved in the construction

Pressure impregnated NTR/AB

Pressure impregnated NTR/AB decking timber is always of the wood type pine. It is pine sapwood that is pressure impregnated with biocidal agents (copper + organic biocides). That is precisely why a good and long resistance to rot is achieved. As a consumer, you get a 20-year warranty against rotting on pressure impregnated NTR/ AB decking (behind the guarantee is the Swedish Wood Protection Association with its members).


Impregnated pine, when delivered, is usually slightly green in color. This is due to the content of copper in the pressure impregnation fluid and the fact that the timber is still damp when it arrives in the trade. In the process, liquid is pushed into the wood/ splint, and it takes a relatively long time to dry. However, it is possible to SiOO:X-treat the impregnated NTR/AB decking when it is surface dry (in normal conditions approx. 2 weeks after the installation of the decking).


A few things to consider when processing NTR/AB (or NTR/A) quality-assured timber:


  • Make sure the pressure impregnated decking timber is dry and clean
  • If there is uncertainty about the humidity of the newly built patio, let it stand and dry for about 6 weeks before the SiOO:X treatment
  • Use stainless steel fittings and screws, other metal may leave “tears” in contact with SiOO:X
  • One tip is to choose larger dimensions, then you usually get better sorting of wood


Larch wood is a common and popular choice if you want beautiful SiOO:X panel or a natural decking. This applies to Siberian lark, which is densely grown and should preferably consist of core timber. Protective reses give the larch a good resistance to rot and fungus. Larch is an oily type of wood and need to rest for one year before treated with Sioo.


With a SiOO:X treatment, the greasy wood opens, the product penetrates and forms amorphous silicon structures inside the wood. SiOO:X Surface protection repels dirt and water on the surface, while the treatment gives the wood a bright glow.


Tips on the lark:


  • Make sure that the larch you buy is of good quality, you can see it on the wooden structure
  • Use larger dimensions of lark then you will automatically get better product
  • Request to measure the moisture ratio of your larch wood. Often the larch can be very moist which is not successful either as a panel or decking
  • According to expertise in durability (SP Wood, SLU), the larch’s resistance to rot is comparable to that of pine heart (about 15+ years), above ground
  • SiOO:X products that fit larch are SiOO:X Premium Wood Protection and Surface Protection Panel and on panel also Wood protective Panel colors with gray pigmentation

Thermo wood

Thermo treatment is a method of modifying wood to improve the properties of wood. The method has been developed in Finland, for example, and means that the timber is heated in an oxygen-free atmosphere of 180-220°C  over a longer period of time. During treatment, changes occur in the chemistry of the wood, which means that it has an improved protective effect against rot but also affects the technical/physical properties of the wood to varying degrees.


Sioo believes that the main advantage of thermotherapy is the greatly improved dimension stability, that the timber is less affected by moisture. This reduces the risk of the wood swelling or shrinking from the surrounding environment.


Cedar is a popular type of wood used in outdoor structures. The timber has natural properties that protect against rot and fungus.


The wood originates from North America and is a Giant Thuija – a coniferous tree. The wood initially has a nice appearance; however, the development of the color depends strongly on the climate and surrounding circumstances. Treated with SiOO:X, cedar develops a silver-gray luster 6 to 12 months after application.


Cedar is used both as a panel and to some extent as decking timber. However, the latter use is less, mainly because the cedar can become ‘rough’ over time.


Cedar with SiOO:X treatment:


  • The cedar must be dry and clean. When treating old cedar surfaces, the surface should be washed / sanded to fresh wood surface
  • Untreated cedar is sensitive to contaminants in the form of fallout from metal coatings or equivalent
  • SiOO:X Wood Protection Panel and Surface Protection Panel are the products that are well suited to cedar
Please select Pro or Consumer
Pro For businesses and architects
Consumer For private individuals