Summer humidity causes wood floor planks to absorb moisture and expand. This moisture imbalance makes the edges of hardwood rise higher than the center. Most minor cupping resolves itself, but severe moisture issues require a flooring professional to fix.
Wavy Wood Floors During a Chicago Summer
You walk across your Palos Park living room during the summer months. You notice something strange about your wood floor. The hardwood floorboards feel wavy under your feet.
This is a common issue for any homeowner in the southwest Chicago suburbs. You will see your wood reacting to these environmental conditions. Your wood floor absorbs much moisture from the humid air.
You might worry that your existing floor is ruined. The good news is that this wood floor cupping is often temporary.
What Exactly Is Hardwood Floor Cupping?
Cupping occurs when the edges of a board rise higher than the center. The bottom of the wood planks absorbs subfloor moisture. This creates a moisture imbalance in the wood fibers. The excess moisture causes the bottom to expand.
Definition: Hardwood floor cupping happens when the edges of hardwood boards push upward. The center of the board stays lower. This makes the floor planks look wavy.
Why Summer Humidity Causes Floor Problems
Since wood is a natural material, it will expand and contract. It absorbs moisture from the air when it is humid. It releases moisture when the air becomes dry.
Chicago summers bring high humidity and temperature and humidity swings. Your home absorbs this humid air easily. A damp basement or crawl space traps this moisture.
The moisture rises through your wood subflooring. It hits the bottom of your wood flooring first.
The Contrast to Winter Gapping
You might remember your wood floor shrinking last winter. Winter air is very dry. This lack of moisture causes gaps between the boards.
Summer cupping is the exact opposite reaction. The installed wood expands as it absorbs summer moisture. The wood floor boards press tightly against each other.
With nowhere else to go, the floor will buckle or cup.
How Moisture Enters Your Home
Chicago summers bring heavy rains. This water finds its way inside. Open windows let humid air flow directly over your floor.
Water in crawl spaces is a major problem. Damp air rises through your subfloor and hits the hardwood floor. A plumbing leak can also push excessive moisture into the wood.
Concrete moisture can seep up if you lack a proper vapor barrier.
Solid Wood vs. Engineered Wood Flooring
The type of flooring you have matters for your wood floor. Solid wood is very prone to cupping due to moisture. A solid wood floor reacts strongly to high humidity. Solid hardwood floors like oak flooring, show cupping easily.
Engineered wood is more stable but not immune. An engineered wood floor has layers designed to resist moisture. However, extreme moisture can still cause engineered flooring to warp. Even engineered hardwood can cup if the moisture content gets too high.
The Importance of Acclimation When Installing
Proper acclimation is crucial when installing a new floor. Acclimation allows the wood to adjust to your home. Installing wood before proper acclimation leads to problems.
Poor acclimation is a leading cause of cupping. We always follow a strict acclimation protocol when installing. When installing solid wood, you must test the subfloor.
Wood floor installation requires patience. Rushing the installation process guarantees moisture issues later. Installing a wood floor correctly prevents many headaches.
How to Tell if Cupping Is Serious
Not all cupping requires you to fix hardwood floor damage. You need to know when to wait.
Normal Seasonal Cupping
Minor cupping during July and August is often normal. If the waves are barely visible, you likely have seasonal cupping. The wood floor will likely flatten when you turn your furnace on. The boards should return to their original shape.
Signs of a Structural Moisture Problem
Sometimes cupping points to a bigger leak. You might have a hidden appliance leak under the floor. If the cupping is severe, you need to investigate.
Do not ignore a cupped floor that feels spongy. You might need moisture testing to find the source.
Steps to Fix Cupped Hardwood Floors
You should never sand a cupped floor while it is wet. Sanding a wet floor will cause it to crown later. Crowning means the center is higher than the edges.
Cupping and crowning ruin a floor if handled wrong. Here is the proper way to fix cupping.
- Find the moisture source: Check for a leak or a damp crawl space.
- Fix the underlying issue: Repair any leaks leading to cupping.
- Control the indoor climate: Run your air conditioning or a dehumidifier.
- Wait for the wood to dry: Give the floor time to return to its original state.
- Test the moisture level: Use a moisture meter to check the wood.
- Consult a professional: Call a local flooring expert if it stays wavy.
35 Years of Chicago Flooring Experience
We have seen thousands of wood floors since 1988. Dean Kuiper personally inspects every wood floor we work on. We often visit homes where people panic over summer cupping.
Our first advice is always to check the relative humidity. Many times, simply running a heavy-duty dehumidifier solves the problem.
We never recommend rushing to sand a wet floor. You must wait for the moisture level to drop. If you sand too early, you ruin the wood floor.
A flooring professional knows when to sand. We only sand when the wood floor is dry. Patience is the best tool for dealing with moisture from the floor.
Protecting Your Hardwood Investment
Your hardwood floor is a major investment. You can prevent cupping by keeping indoor humidity balanced.
Use your AC and a dehumidifier to control the climate. Never wet mop a wood floor, as this forces water into the seams. Proper maintenance and care keeps your wood floor beautiful.
If the damage is permanent, professional hardwood floor refinishing can help.
Common Questions About Summer Floor Cupping
Will a cupped floor flatten out on its own?
Yes, minor cupping often flattens out when winter returns. You must fix any active leak for the wood floor to recover.
Should I sand my cupped floors right away?
No, you should never sand a wet wood floor. Sanding wet wood will cause the wood to crown later.
Does a dehumidifier help with a cupped floor?
Yes, a dehumidifier removes moisture from the air. This helps draw moisture out so the boards can flatten.
Can I mop my wood floor in the summer?
You should never wet mop a wood floor. This adds too much moisture and can cause the wood to warp.
Get an Honest Assessment for Your Floors
Are you worried about your hardwood floor cupping? You deserve an honest evaluation without a sales pitch. Dean’s Floor Service has guided southwest suburban homeowners since 1988.
Contact us today to schedule a consultation.
Important Points to Remember
- Find and fix any leak before attempting to fix cupping.
- Maintain proper humidity levels to prevent cupping.
- Summer humidity causes wood floor planks to expand and buckle.
- Cupping occurs when the edges rise higher than the center.
- Expect minor cupping to resolve when you turn your AC off in fall.
- Check for subfloor moisture or a damp basement if cupping is severe.
- Never allow anyone to sand your wood floor while the wood’s moisture is high.
- Consult a flooring professional if your wood floor does not flatten.
- Proper acclimation is vital when installing a new floor.