How Does Water Get Under Hardwood Floors?

Water finds its way under hardwood through the small spaces between planks, around nail holes, and at the edges where flooring meets walls or thresholds. Even a minor spill can seep into these gaps if left sitting. Over time, the wood swells and creates larger openings that let more water in.

Another entry point is the subfloor. If you have a crawlspace, groundwater or plumbing leaks can wet the subfloor from below, and that moisture rises into the hardwood. In a humid coastal climate, moisture can also push through concrete slabs, especially during storm season.

• Spills that sit on the surface
• Leaks from appliances or pipes
• High indoor humidity
• Moisture from a wet subfloor
• Flooding from storms or overflows

You might notice warping, cupping, or buckling of the planks. Dark stains or discoloration can appear along seams. A musty odor often develops as moisture sits under the wood. If you press on a plank and it feels soft or spongy, water is likely trapped beneath.

Another sign is a change in the floor's finish, like peeling or blistering. You may also see small gaps forming between planks as they dry and shrink unevenly. Catching these signs early can prevent more extensive damage to your subfloor and framing.

If the water has been sitting for more than a day, or if you see mold or a musty smell, professional help is wise. The pros have moisture meters and drying equipment that can reach under the floor. They can also assess whether the subfloor is damaged.

For large floods or contaminated water, do not attempt cleanup yourself. The pros follow safety protocols for handling hazardous water. They can also help with documentation for your insurance claim. Policies vary, and your insurer decides what is covered.