Quick Takeaways
- Gaps between floorboards are normal and usually caused by seasonal shrinkage, air‑conditioning, direct sunlight, or sub‑floor moisture conditions.
- Filling gaps is not recommended — timber expands and contracts, causing filler to crack, break out, and look worse over time.
- The only reliable exception is repairing a single large, isolated gap using a timber sliver, which moves naturally with the floor.
What Causes Gaps Between Floorboards?
Our Brisbane floor sanding clients often ask, 'Can you fill the gaps between our polished floorboards?' The size of the gaps can vary—some floors have tight spacing, while others may have gaps as wide as 5mm. First, the reason for the gaps will vary.
Floors laid with gaps
Floors that are originally laid with gaps may experience further widening over time due to environmental factors.
Seasonal shrinkage
Dry months can cause wood shrinkage, leading to an increase in the gaps between floorboards.
Effect of air conditioning
Air conditioning can dry out the wood, resulting in gap expansion similar to the effect of seasonal shrinkage.
Old Floors Shrinking
The issue is more common in older timber floors. While heating and cooling your home can contribute to gaps widening, other factors, such as direct sunlight or heat, can also play a role. For instance, glass doors or windows that allow direct sunlight to enter can heat specific areas of the floor and cause it to dry out. This effect is usually limited to isolated sections.
Sub-Floor Conditions
Additionally, underfloor conditions can impact the timber. Airflow beneath the polished floorboards may dry out the underside, leading to gap expansion. Conversely, excess moisture can have the opposite effect. Poor drainage systems can trap moisture beneath a home, causing the timber floorboards to absorb the moisture and expand.
Can the Gaps be Filled?
The short answer is no: Sometimes customers ask to have these gaps filled. In brief, it is not a good idea. Yes, the floor would look better with the gaps filled. Sadly, it will always crack and break out. Also. it will break out in bits and pieces. As a professional floor sander in Brisbane, we want the very best result for our clients, offering a full scope of services from restoration to repair.
Expansion & Contraction
This image illustrates the contraction of the floorboards, which causes the filler to crack. The cracking occurs not only along the edges but also through the center.
The Australian Timber Flooring Association (A.T.F.A.) explains in more detail about the effect of expansion and contraction with floorboards. The Q.B.C.C. uses A.T.F.A. guidance for timber flooring issues because they provide specialised expertise and industry standards for assessing and resolving flooring-related concerns.
The Problems That Will Occur
Occasionally, we encounter old timber floors with filler between the polished floorboards. While some pieces of filler may remain intact, they often dislodge or go missing over time. This leads to an uneven appearance that is difficult to remedy. In summary, the question, 'Can you fill gaps between floorboards successfully?' has a straightforward answer: no. Timber is a natural material that adapts and shifts in response to its environment and climate.
The Exception to the Rule
For example, if there is one particularly large and isolated gap between two floorboards that detracts from the overall appearance of the floor, a practical solution would be to glue a sliver of timber into the gap to achieve a more uniform look. This method offers greater flexibility in accommodating the natural expansion and contraction of the timber. Karl, from Economy Floor Sanding, is one of Brisbane's leading experts in timber floor sanding. During an on-site quote, he will provide professional guidance to help you achieve the best possible result for your floors. See our full 2026 Homeowner’s Guide to Floor Sanding.
Want to Talk to a Flooring Expert?
Karl from Economy Floor Sanding
Arrange an onsite floor inspection with Karl from Economy Floor Sanding Brisbane, your direct line to expert advice and craftsmanship.
What You Get
- Over 28 years’ experience in the floor sanding industry
- A meticulous tradesman, using refined sanding techniques
- Extensive knowledge in timber floor restoration
- Highly skilled at stainig & colour matching