Natural Behaviour of Timber
Timber is a natural, living material that responds to its environment. Exposure to moisture, heat, UV rays, and changes in temperature can cause movement in the form of warping, twisting, bowing, swelling, shrinking, splitting, surface cracks, and discolouration. These natural characteristics are not considered defects, but inherent properties of timber especially when used in outdoor settings.

Is cracking in timber a defect?
No. Timber cracks and splits are a natural characteristic that occurs when wood adjusts to its environment. These movements are to be expected when timber is in outdoor setting, including fencing panels, gate posts, decking, sleepers, and timber structures such as, summerhouses, sheds, fencing panels, pergolas and gazebos. Most timber used in buildings is pressure treated and/or kiln dried to minimise, but not eliminate, this natural movement.

​Cracking in timber should not be interpreted as a defect or a sign of poor quality. On the contrary, this is a natural indication that the wood is responding correctly to fluctuations in temperature and humidity.​ Visible checks appearing in decking boards or summerhouse walls are standard characteristics of timber behavior and are not structural faults.

What can be done to help prevent timber splitting?
While timber movement cannot be completely stopped, there are ways to reduce cracking in landscaping timbers:

- Allow the timber to acclimatise - let the timber structure sit in its new environment for a while before installation to reduce initial stress.

- Seal the ends of the timber - apply a quality end-grain sealer or wax to freshly cut timber ends to reduce rapid moisture loss and minimise the risk of cracking or splitting.

- Use protective finishes - oils, uv, stains and paints reduce moisture exchange and are highly recommended for all timber buildings.

- Avoid exposing fresh wood to intense sun: store components in a shaded or covered area to allow gradual drying before assembling.

How Can I Treat Cracked Wood?
Cracks and splits in wood will often close up on their own once moisture levels stabilise. Cracks and shakes caused by changes in humidity can close up as the wood continues to absorb moisture and expand though the seasons.

Although these seasonal changes are a natural settling process that is part of the beauty of wood, if the 'appearance' of the cracks is unwanted the following action can be taken to restore the look of wood:
- Wait 6-12 months for the timber to fully settle through the seasonal changes
- Fill surface cracks with flexible wood filler or exterior-grade caulk
- Sand and refinish with an oil, stain or paint to restore visual consistency

Other Natural Wood Characteristics
Wood has many characteristics that are completely normal and do not affect timber quality or performance. So, if you see these appear in your timber, they’re not usually anything to worry about.

Rough spots / edges - caused by knots and processing / saw milling direction, especially visible on cladding boards or sawn products such as fencing.

Resin marks - common in freshly treated wood, especially pine (can be cleaned with white spirit or gently scraped). 

Pith - a darker core sometimes visible in wall logs or structural posts (not wood rot).

Green spots / salt marks - harmless salt crystals on pressure-treated fencing, sleepers or shed cladding.

Fungal staining or mildew - these are temporary,  typically caused by moisture in freshly treated timber.

Knots and flames - these are naturally occurring patterns that give timber its unique look.