Common Hardwood Flooring Defects and What Causes Them
Updated: 3 days ago
Need an independent answer about your floor? Contact NWFA certified inspector Joe Avila:
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Email: joe@hugginsflooring.com
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When a hardwood floor goes wrong, the symptom you see isn't always the problem. Gaps, ridges and peeling finish each point back to a cause, and finding that cause decides how the floor gets fixed and who pays for it. Here are the most common hardwood flooring defects an NWFA certified inspector sees across the country, and what usually causes each one.
Moisture-related Defects
Most hardwood flooring defects start with moisture. Wood gains and loses water with the air around it and with what's underneath it. See what moisture content is normal for hardwood floors.
Cupping. Board edges sit higher than the center. Usually the bottom of the board is wetter than the top: a damp crawlspace, a wet slab, a leak, or high humidity. Read more about cupping.
Crowning. The center of each board is higher than its edges. Most often it comes from sanding a cupped floor before it dried. Read more about crowning.
Buckling. Boards lift off the subfloor, sometimes by inches. This is the most severe moisture reaction, usually from flooding or a long-term leak. Read more about buckling.
Gaps. Spaces open between boards when the wood dries and shrinks, often in winter when heating dries the air. Small seasonal gaps are normal. Read about winter gaps.
Checking and splitting. Cracks along the grain or at board ends, usually from very dry conditions.
Installation-related Defects
Peaking and tenting. Boards push against each other and lift at the joints when there's no room to expand. Common with missing expansion space or floating floors pinned under cabinets. Read about engineered flooring problems.
Squeaks and movement. Loose fasteners, too few fasteners, or an uneven or under-fastened subfloor.
Hollow spots in glue-down floors. Poor adhesive coverage or transfer, an uneven slab, or moisture breaking the bond.
Overwood and lippage. Uneven board heights at the joints, from subfloor flatness problems or milling variation.
Problems from poor acclimation. Flooring installed before the home reached normal living conditions. Read about acclimation.
Finish And Surface Defects
Peeling or flaking finish. Often caused by poor adhesion between coats, contamination such as cleaning products or silicone, or skipped abrasion between coats.
Bubbles, dust nibs and lap marks. Usually application or job-site conditions during finishing.
Excessive scratching or premature wear. Can point to the finish system, grit and maintenance, or furniture without pads.
Discoloration and color change. Sunlight (UV) is normal for many species. Dark stains can come from water or pet urine reacting with the wood.
Product-related Defects
Some defects come from the flooring itself: milling problems, inconsistent board dimensions, finish defects from the factory, or engineered flooring delamination. Telling a product defect from an installation or site problem is the core of most claims. See installation defect or manufacturing defect?
Why The Cause Matters
Two floors with the same symptom can have completely different causes, and different people responsible for them. That's why manufacturers and insurers rely on an independent hardwood floor inspection before deciding a claim.
Quick Answers About Hardwood Flooring Defects
What Is The Most Common Hardwood Flooring Defect?
Moisture-related defects are the most common, especially cupping and gaps. Most hardwood failures trace back to moisture from below the floor, from the air, or from leaks.
Are Gaps In Hardwood Floors A Defect?
Small gaps that open in dry winter months and close in humid months are normal seasonal movement, not a defect. Large or permanent gaps can point to installation or moisture problems.
How Do I Know If My Floor Problem Is The Installer's Fault Or The Product's?
An independent inspection compares moisture readings, installation methods and job-site conditions against the manufacturer's instructions and NWFA guidelines to determine the cause.
Does A Flooring Warranty Cover Defects?
Most warranties cover manufacturing defects but not damage from moisture, installation errors, or improper care. A documented cause is what decides the claim.
Have A Defect You Can't Explain?
National Wood Floor Consultants provides NWFA certified hardwood floor inspections nationwide. Call (908) 232-6600 or book a consultation with inspector Joe Avila.
About The Author
Joe Avila is the founder and lead consultant of National Wood Floor Consultants, with 26 years in wood flooring. He is an NWFA Certified Wood Flooring Inspector, installer and sander, and teaches accredited AIA, ASID and IDCEC continuing education for architects and designers. His project experience includes Montclair University, One Wall Street, institutional and landmark buildings, and luxury residences and penthouses, and he pioneered subfloor sound-attenuation systems for New York City apartments. Read Joe's full profile.
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