A crack in a gazebo post, a knot, a gap between boards or a change in facade colour can be worrying, especially when they appear right after assembly. However, not every such change means a material defect or damage to the structure. Wood is a natural, hygroscopic material – it reacts to humidity, temperature and conditions of use. That is why its appearance and dimensions change over time. It is worth knowing which phenomena may result from the natural movement of wood, and when a closer assessment is needed.
Why does wood move? Causes of natural changes in the material
Wood is a hygroscopic material, so it reacts to its surroundings throughout its entire service life. This means that it:
absorbs and releases moisture,
shrinks and swells,
reacts to changes in temperature,
moves mainly across the grain,
may move more intensely in solid wood elements with a larger cross-section.
Drewnolandia structures are built with kiln-dried wood. This process lowers the moisture content of the material before machining and improves its stability, but it does not stop the wood from reacting to its surroundings later on. We explain more in our guide to kiln drying of wood and in the article on the wood we use in the production of Drewnolandia cabins.
Are shrinkage cracks a wood defect?
Longitudinal cracks occur when the outer layers of an element dry faster than its core. The difference in the rate of moisture release creates stress, which can result in a split running along the grain. Such cracks are typical above all for posts, beams, square timbers and other solid wood elements with a large cross-section. The mere presence of a crack does not mean the element is defective. What matters is its direction, extent, location and the function of that part of the structure.
Through cracks, cracks running across the grain, or cracks accompanied by clear deformation require particular assessment. It is also worth remembering that solid and glulam timber behave differently – we describe this in more detail in the article: "Solid wood vs. glulam".
Knots in wood as a natural feature of the material
Knots form where branches once grew out of the trunk. They are therefore a natural part of the wood's structure, and their presence alone does not mean poor material quality. Sound, tightly grown-in knots are part of the natural grain pattern. Loose knots, knots that fall out or leave a hole call for more attention. In structural elements, their position also matters.
Resin leaking onto the wood surface
Resin is a natural component of coniferous wood, including pine and spruce. It may appear on the surface, especially on warmer, sunny days, and it is often visible near knots. The kiln drying used in our structures limits this phenomenon, but does not always eliminate it completely.
Once resin has seeped out, it is best to leave it to harden. A dried droplet can be gently removed, and any residue cleaned off with a product designed for removing resin.
Wood turning grey due to UV and moisture
One natural phenomenon that may worry users is the greying of wood. The silvery-grey colour of the surface is the effect of UV radiation and moisture. The process affects only the outer layer of the material, 0.05 to 0.5 mm thick – a fraction of a millimetre. It does not reach deep into the wood's structure and does not change the load-bearing capacity of the structure. It is therefore primarily a visual effect of the natural ageing of a surface exposed to the weather, not a sign of a weakened structure.
Wood preservation can slow down visible changes and make it easier to refresh the wood later, but it does not stop them completely. We cover this topic in more detail in the guide: "Wood greying – a natural process".
Cupping and minor board deformations
When drying is uneven, a board may bend slightly across its width, taking on a trough-like shape. This phenomenon is called cupping and results from different parts of the element releasing moisture at different rates.
Minor deformations of finishing elements can result from the natural movement of wood. However, if the deformation affects the tightness of a wall, makes doors or windows hard to operate, or concerns a structural element, it is worth reporting it to the manufacturer for assessment.
What causes gaps between boards?
When humidity drops, wood shrinks, so visible gaps may appear between boards. This applies, among others, to wall panelling, floors and other finishing elements. The change is often seasonal – when humidity rises, the material may expand again and the gaps partly close. You should therefore not automatically seal every gap without establishing its cause. A sealed gap prevents the material from moving back – when humidity rises, the board has nowhere to swell, which can lead to warping or damage to neighbouring elements. If a gap quickly widens or causes a leak, it needs a closer assessment.
Tongue sliding out of the groove in facade boards
Tongue-and-groove facade boards also react to changes in humidity. As the board shrinks, the tongue may partly slide out of the groove. According to an independent technical opinion prepared by a building expert, a partial withdrawal of the tongue from the groove of up to 7 mm is acceptable, provided the joint still performs its function and remains tight. A tongue that comes out completely, or a loss of tightness, requires a separate assessment.
Where do cracking and creaking noises in the structure come from?
Cracking and creaking sounds may result from the natural movement of wood in response to changes in temperature and humidity. They are particularly noticeable during sudden changes in conditions and in the first period of using the structure. If the noises are accompanied by deformation, shifting of elements or tightness problems, it is worth reporting them to the manufacturer for assessment.
Fading coatings and deposits on wood
Protective coatings lose their properties over time due to sun, rain and moisture. The pace of these changes depends on how exposed each wall is. A weakened surface holds dust and organic particles more easily, and in higher humidity deposits may appear on it. This is a signal to clean and renew the protection. You can find more information in our guides to ways of protecting wood and on which wood preservative to choose.
Which changes can be considered natural wood defects?
The term "natural wood defects" is often used colloquially, although many of these phenomena are in fact natural characteristics or effects of the material's movement. This group includes:
sound knots,
shrinkage cracks,
resin leaks,
greying,
minor gaps resulting from shrinkage,
slight board deformations.
However, this does not mean that every change should be considered natural. The assessment must take into account its extent, location and impact on the durability, tightness and use of the structure.
When should you report a change to the manufacturer of a gazebo or wooden cabin?
A closer assessment is needed above all for through cracks or cracks running across the grain, clear deformation of structural elements, a tongue sliding out of the groove completely, loss of tightness, leaks, and problems with the operation of doors and windows. You should also report knots that fall out and leave holes, visible signs of mould, fungi or insects, and assembly irregularities.
It is best to send a photo of the whole element and a close-up of the area that raises concern. For a crack or gap, a photo with a measuring tape placed next to it will also help. We accept reports at serwis@drewnolandia.pl. Please provide the order number or the date of delivery and attach the photos described above. We reply within 14 days.
How can you limit the effects of wood's natural movement?
The natural movement of wood cannot be eliminated completely, but its effects can be limited. Above all, it is worth to:
regularly check protective coatings,
ensure good ventilation,
avoid prolonged dampness,
make sure water drains away properly,
limit contact between wood and the ground or snow,
keep the indoor air humidity in all-year cabins within 40–60%.
During the heating season, indoor humidity often drops below 30%, which increases wood shrinkage and widens gaps. Consider using a humidifier – it is also good for the health of the household.
Frequently asked questions about wood defects in gazebos and cabins (FAQ)
Wood can keep changing throughout the entire service life of a structure. Below we answer the most common questions about its natural properties.
Are cracks in wood normal?
Longitudinal shrinkage cracks can result from the natural release of moisture. However, their direction, extent and location matter.
Do knots mean the wood is defective?
Sound, tightly grown-in knots are a natural part of the material's structure. Above all, loose knots, those that fall out and those that leave holes need to be assessed.
Does resin seeping from wood indicate poor quality?
No. Resin is a natural component of coniferous wood and may appear on the surface especially at higher temperatures and in strong sunlight. Once it has hardened, it can be carefully removed.
Can gaps between boards appear after assembly?
Yes. Wood changes its dimensions as humidity changes, so small gaps may appear between boards from time to time. However, if a gap clearly widens or causes a leak, it is worth consulting the manufacturer.
When should you report changes in a wooden structure to the manufacturer?
When it raises doubts about the safety, tightness or use of the structure. It is worth sending photos and, if possible, a measurement of the change.
The detailed scope of the warranty and the limit values for individual phenomena are described in the document "Natural properties of wood and the scope of the warranty", which is given to every Customer upon handover of the building.