Hardwood Floor Crowning: Causes, Fixes and How It Differs From Cupping
Updated: 9 hours ago
Need an independent answer about your floor? Contact NWFA certified inspector Joe Avila:
Phone: (908) 232-6600
Email: joe@hugginsflooring.com
Book online: Schedule a consultation
Office: 406B W Broad Street, Westfield, NJ 07090. Serving clients nationwide.
Crowning is the reverse of cupping. The center of each board is higher than its edges, so the floor looks slightly convex or "domed" from board to board. It's less common than cupping, and it's often a sign that something was done in the wrong order.
What Is Crowning In A Hardwood Floor?
Crowning is when the middle of each hardwood board sits higher than its edges. Run your hand across the boards and you feel a gentle hump in each one, instead of the raised edges you feel with cupping.
What Causes Hardwood Floors To Crown?
There are two main causes:
Sanding a cupped floor too soon. This is the most common cause. A floor cups from moisture underneath, and someone sands the raised edges flat before the moisture problem is fixed and the boards dry out. When the wood later dries, the edges shrink back down below the center and the floor crowns.
Moisture on the top surface. Less often, prolonged moisture from above, such as spills, wet mopping, a leak or very high indoor humidity, makes the top of the boards swell more than the bottom.
Crowning can also appear as a phase while a cupped floor dries out, which is why the timing of any repair matters.
Crowning Vs Cupping Vs Buckling
Can A Crowned Hardwood Floor Be Fixed?
Often, yes, but in the right order:
Find and fix the moisture source, if there is one.
Let the floor stabilize. Bring humidity back to normal living conditions and confirm with moisture readings over time.
Then evaluate. Some crowning settles once moisture is in balance. If it doesn't, the floor may be resanded and refinished once it's stable, as long as the wear layer is thick enough.
Sanding before the floor is stable just repeats the problem in the opposite direction.
Quick Answers About Hardwood Floor Crowning
What Causes Hardwood Floors To Crown?
Most often, a cupped floor that was sanded flat before it dried. When the boards later lose moisture, the edges shrink below the center. Moisture on the surface from spills, leaks or high humidity can also cause it.
Is Crowning Worse Than Cupping?
Crowning is often harder to reverse, because it usually means wood was already removed by sanding. Cupping caused by moisture can flatten once the moisture source is fixed and the floor dries.
Will A Crowned Floor Go Back To Normal?
Some crowning eases once indoor humidity and moisture content are back in balance. Permanent crowning is usually corrected by sanding and refinishing after the floor is stable.
Should I Sand A Cupped Floor Right Away?
No. Fix the moisture source and let the floor dry and stabilize first. Sanding too early is the main cause of crowning.
Not Sure Why Your Floor Is Crowning?
An NWFA certified inspector can confirm the cause and tell you when it's safe to repair. Call (908) 232-6600 or book a consultation. We provide independent hardwood floor inspections nationwide.
Looking for hardwood flooring inspectors you can trust? Our guide explains how to find one and check their NWFA certification.
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.
Comments