Filling gaps in floorboards

Summary: Learn how to fill gaps in floorboards, use foam backer rods to fill floorboard gaps and use caulk/silicone sealant to seal the gap between floorboards.

Older homes that have retained old hardwood floorboards may have unwanted gaps between the boards. Over time the timber separates leaving noticeable spacing which can become home to dirt and debris, or they may allow drafts into the room. It may be necessary to remove and replace the old timber, however in the interest of time and cost, it is possible to fill the gaps instead. This is known as caulking and is best done before you fully refurbish the floors.

How to fill floorboard gaps

  • Firstly to prepare the floor gaps so they can be filled, you must clear them of all dirt and dust. Use an implement such as a knife or screwdriver to get right into the gaps. Be careful not to scratch the surface of the floorboards. Use a vacuum cleaner to remove all the dirt.
  • Squeeze foam backer rods into all the spaces they will fit into. These are lengths of coiled foam that reduce the space in between the boards and help prevent drafts.
  • The remaining space between the boards needs to be filled with caulk. Apply urethane caulk into the gaps on top of the foam backer by using a caulk gun. This will help with the dispensing of the caulk and will make sure it reaches the areas you intend to fill. Purchase a caulk that matches the colour of the stain on your wooden floor.
  • In a similar way to grouting tiles, you want to smooth the caulk between the boards so it is level or slightly below the surface level. Do this by wetting your finger and gently running it along the length of the gap.
  • Allow the caulk to dry fully (refer to manufacturer’s instructions for length of time required) before attempting further finishing or cleaning work on the boards. The time needed may be affected by the amount of caulk used and the humidity and temperature of the environment it is in.

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