Hardwood Floor Problems: Cupping, Lippage, Splitting, Gaps, Buckling

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The wooden floor is one of the best popular-most installed and preferred floorings due to its durability, easy maintenance. It also provides one of the most comfortable feel as well as good ambiance. But, does it have any drawbacks?

The wood flooring, however, doesn’t come without a few limitations. Warping, cupping, lippage, splitting, buckling, and bubbling are some of the mains problems that occur on the hardwood floor. High moisture content is the main culprit. The wood floor installers need to determine the moisture content correctly to avoid these problems.

In this article we look at some of the structural problems expected or experienced and their possible causes and solutions.

15 Possible Structural Problems of Wooden Flooring

Hardwood floor problems
Wooden Floor

1. Adhesive Failure

floor adhesive failure problem
Adhesive failure

Flooring adhesive failure may occur due to:

  • Moisture-if the flooring is installed when too wet or dry or the surrounding becomes too wet or dry. This causes wood shrinkage or expansion that can overcome the adhesive bond.
  • The insufficient adhesive between substrate and flooring. Application using the wrong trowel may create an insufficient bond. This may at times lead to wood floor bubbling.
  • Contaminated substrate– this may cause adhesive failure.


  • Verify the flooring is adequately bonded to the substrate. You may also consider other methods used to fix bubbling on the wood floor.
  • Take moisture reading to rule out as a course of failure. In-case it’s the cause, take appropriate remedy before re-installing.
  • Take slab history to avoid contamination. Sand or grid the sealed slab to un-contaminate the concrete.

2. Buckling and Bridging

This is an extreme problem of cupping. It occurs where there is a moisture difference between sub-floor and floor covering is too great during installation. The flooring is prone to expansion to an extent that the planks may pull away from the sub-floor layer. Other causes, all related to moisture content include.

  • The flooring may have been improperly acclimated or installers at a too low moisture content
  • The inadequate gap being left between the flooring.
  • Increased room moisture either through flooding or spike in seasonal moisture from the flooring foundation.
Buckling and bridging problem


Its possible to fix buckling wood floor with the following methods.

  • Remove the buckled boards.
  • Avoid re-installing before verifying the moisture content.
  • Framing within acceptable limits.
  • Refasten the flooring.
Joist bridging problem
Joist bridging

3. Crowning

This is due to moisture imbalance; the top is wetter that below. Crowning occurs where the center of the flooring board is higher than its edges. This occurs after the flooring board absorbs ambient moisture and expands beyond the space left. With no space to go, the expanding planks swell or push up in the middle section of the board. This is a common problem where the floor that had cupped was sanded flat.

floor crowning  problem


  • Testing to confirm the floor moisture is acceptable
  • Sand flat and refinish.

4. Cupping

Its caused by moisture imbalance. When the bottom becomes wetter than the top floorboard, it causes the boards to expand more on the bottom part than the top. This makes the board swell and expand. If there is an insufficient gap between boards for expansion, the edges of the expanding planks are forced upwards and cupping occurs.

floor cupping problem
Floor Cupping


  • Maintain cupping of 0.01″ for plank floors in normal condition and of 0.02″ for ones that require special attention.
  • Avoid sanding until moisture below and on top is within 1%.
  • Allow the floor to go through one complete heating season.
  • Installing the waterproof underlayment between the subfloor and the floor covering would help reduce the moisture content.

5. Delamination

The main cause is manufacturing defects. Another cause is installation-related problems like an overlay flexible subfloor, excessive heat from duck, excessive moisture, etc.


  • Test for manufacturing defects.
  • Verify the site meets flooring specifications.
Flooring delamination problem

The main cause, being high heeled shoes and furniture with missing tips on their legs.

6. Dents

  • You can try to swell the dent to the surface using a damp cloth and electric iron
  • Re-sanding the floor
  • Replacing the board

7. Fractures and Prefinished Board Edges

The fractures are a result of the use of improper nailers or unexperienced flooring professionals.


  • Replace the flooring board
  • Use manufacturer supplied adapters on nailers to avoid damage.

8. Gaps; Above Floor Beam, From the Cross Pull, From Installation, Penalization.

The wood floor may get too big and irregular gaps. These abnormal gaps occur due to expansion and contraction as a result of environmental changes. Humidity and high moisture content make the wood floor absorb a lot of water and end up expanding.

More sunlight leads to excessive dryness that makes the wood floor lose the absorbed water thereby contracting to leave gaps that destroy its aesthetic look. Failing to keep floorboard straight during installation, seeps between groups of boards glued together.

floor gaps problem
Floor Gaps


9. Lippage or Overwood

Mainly caused by loose-fitting tongue and groove joints and an uneven floor that may be as a result of debris below flooring.


  • Replacing the board.
  • The entire floor should be sanded and finished.

10. Powder Post Beetles

Beetle infestation is one of the common problems in the sapwood. Air-dried wood may contain larvae and even kiln-dried wood may pick beetles during storage. When the larvae emerge from the wood they leave a weakened area on your flooring.

termite flooring problem
Termite floor damage


  • Fill the old infested holes with the furnish.
  • Remove infested boards.
  • Consult an exterminator to avoid widespread infestation.

11. Rot

Flooring rot problem
Floor Rot

Rot is caused by excessive moisture for an extended period of time. Alternatively, it may be due to leaking plumbing.


  • Address moisture problem and verify with a moisture meter
  • Framing to reach moisture content equilibrium.
  • Replace rotted boards.
  • Sand and coat.

12. Shake

Wing or ring shake which is a separation of wood flooring at the growth rings which causes internal tension. It may also be as a result of overly rapid kiln drying.

flooring ring shake problem
Ring Shake


  • Ensure subflooring and flooring are of correct moisture content.
  • Replace the affected boards.
  • Cull boards with shake when installing.
  • Allow one full heating season for the shake to appear.

13. Shell Out

This is a maintenance issue. Using excessive water when mopping, heavy traffic and regular furniture movements. This causes wear and tear of soft layers of wood.


  • Sand and recoat the flooring.
  • Avoid excessive water when mopping.
  • Ensure your furniture has wide castors or tip rubbers or appropriate tips.

14. Splinters

The causes include: splitting is a moisture-related problem. Sanding one too many times may make the flooring thin enough to splinter. The irregular subfloor may cause an edge to raise or even the grain may raise due to moisture.

floor splitting problem


  • Replaced sanded floor past its lifespan.
  • Check moisture problems to maintain equilibrium.
  • Screen, sand, and recoat.
  • You may also glue splinters from natural defects.

15. Squeaky or Loose Floors

Floor squeaks are caused by movement either between flooring and subfloor on in the framing. Using too few nails in either the subfloor or in the flooring may cause squeaks.


  • Take careful inspection to determine the cause of loose floors.
  • Shimming and injecting construction adhesives help solve the loose flooring problem.
  • Screwing the boards through the flooring to the subfloor.
floor sagging and sloping problem
Floor Sagging and Slopping
Floating floor problem
Floating Floor

Ways to prevent Hardwood Floor Problems

  • Measure the moisture content when building the layers of the floor especially the subfloor. This will help take appropriate measures at different levels of construction of floor systems like using the best underlayment between subfloor and floor covering.
  • Always consider the floor covering the moisture tolerant limit. This will help you choose the best flooring for your floor needs.
  • Remember to read manufacturers’ instructions for the appropriate expansion and contraction gaps. Don’t assume all flooring has the same expansion gaps.
  • Consider using a wood moisture meter to determine the moisture content of your flooring components before during and after installation.
  • Remember it’s always better to avoid a problem rather than fixing it. Always take appropriate precautions, use the right tools for hardwood like best vacuum cleaners, and select the right cleaning solutions meant for wood floor.
  • Always Acclimate the wood flooring correctly before installing it.

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Joe McGuinty
I’ve been working with floors for over 12 years. I started as a flooring contractor, primarily in materials selection. Then, I switched careers into accounting, so my wife and I began buying, renovating, and re-selling homes on the side. You’d be surprised how much value you can add to a home simply by adding new floors.

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