How do I fill gaps in hardwood floors?

Filling gaps in hardwood floors is a common maintenance task in Ottawa homes, and the right approach depends on the size of the gap and whether it's seasonal or permanent.

Hardwood floors naturally expand and contract with humidity changes — and Ottawa's climate makes this especially pronounced. Our cold, dry winters and humid summers create significant seasonal movement. Before you fill anything, observe the gaps through at least one full seasonal cycle. Gaps that appear in winter and close up in spring are seasonal gaps caused by normal wood movement, and filling them can actually cause buckling when the wood expands again.

If the gaps are consistent year-round, or larger than about 3mm (⅛ inch), they're worth addressing. For small gaps under 3mm, a flexible wood filler or latex-based wood putty is your best option. Choose a colour that matches your floor finish, apply it with a putty knife, let it cure fully, then sand flush and refinish the area. Minwax, Timbermate, and similar products are available at Ottawa hardware stores like Home Depot, Rona, or Home Hardware. Avoid rigid fillers like wood epoxy in areas with seasonal movement — they'll crack.

For medium gaps (3–6mm), rope caulk or flexible wood filler works well. Some flooring specialists use a coloured wood filler mixed with fine sawdust from the actual floor for a near-invisible match. For large or widespread gaps, you may be looking at a more significant issue — subfloor movement, improper installation, or severe moisture damage — and a professional assessment is worth the call.

Ottawa-Specific Considerations

Ottawa's freeze-thaw climate and forced-air heating systems are particularly hard on hardwood. Running a humidifier during winter (targeting 35–45% relative humidity) is one of the best ways to minimize gap formation in the first place. Many Ottawa homes with older hardwood — especially post-war bungalows in Alta Vista, Elmvale, or Carlington — have floors that have been through decades of this movement, and widespread gapping may signal the floor needs a full sand and refinish rather than spot filling.

DIY is absolutely appropriate for small gap filling — it's low-risk, low-cost, and straightforward. Materials will run you $15–$40 at a local hardware store. If gaps are widespread, the floor is cupping or buckling, or you suspect a moisture problem underneath, that's when a flooring professional should take a look. A professional assessment typically runs $75–$150 for an in-home consultation, and a full sand and refinish on an average Ottawa home (1,000–1,500 sq ft) runs $2,500–$5,000 depending on condition and finish type.

Your next step: Check the gaps in both winter and summer before committing to a fill. If they're seasonal, invest in a humidifier instead. If they're permanent, pick up a colour-matched flexible wood filler and tackle it as a weekend project. If the gaps are widespread or you're seeing any floor movement or moisture signs, reach out to a flooring professional through the Ottawa Construction Network directory for an honest assessment.