Every hardwood floor endures some separation between boards. In the winter months when the home is heated and the air is dry, wood flooring releases some of its moisture and therefore shrinks. When this happens, thin cracks appear between boards. This is normal and is acceptable.
To prevent large gaps in your wood floors, stabilize your home's relative humidity by using a humidifier in the winter months. Use exhaust fans and dehumidifiers to prevent too much moisture in the summer months. Small gaps less than 3⁄32 inch in width can be filled with wood filler.
Why do floor boards separate? Wood is a completely natural product and as such expands and contracts when it comes in contact with moisture and temperature fluctuations. As a general rule of thumb, when temperatures are on the hot side and moisture levels are high in the air, wood takes in the moisture and expands.
For normal gaps, no repairs are needed. Adding filler is not a good idea; it will get pushed out as the wood expands with moisture. For larger gaps that don't close up, call in a professional contractor who can repair floors properly. The best times to repair hardwood floors are April and October.
Generally speaking, gaps in a wood floor are normal for boards up to 2¼ inches wide if the gaps close during more humid times of the year. Normal gaps can vary in width, ranging from hairline gaps to the thickness of a quarter.
The idea is that you stick the floor gap fixer on the board that has a gap at the end and wack it with the mallet. This closes one gap and opens up another behind it. You then close that gap, and the next, and the next until you've hidden the gap behind the nearest baseboard.
Solid hardwood floors move in sync with fluctuating conditions in their environment. They expand when the humidity increases, and contract when it decreases. During the winter months, contracting floors will often leave thin cracks or gaps between the planks.
Leaving the right expansion gap is an essential part of fitting any wooden floor. Whether it be solid wood, engineered wood or parquet block flooring, they all need an expansion gap to allow for natural movements when the wood expands and contracts with changes in the surrounding atmosphere.
During the winter, when homes are heated and the air is dry, wood flooring loses some of its moisture and contracts or shrinks as a result. It is normal that when relative humidity is lower than recommended, wood plank shrinks, therefore thin gaps can appear between wood planks.
A flexible putty knife, a stiff brush and a vacuum might be helpful. Then, he suggests that you mask off the edges of the boards but leave the gaps exposed. Painter's masking tape, often blue, would work for this. With a plastic putty knife, you can then spread gap filler in the openings and smooth it level.