10 Common Flooring Mistakes that Can Void your Warranty

April 17, 2026

by Joel Hirshberg

Most flooring failures aren’t product failures.

They’re installation failures.

The good news? Almost all of them are avoidable if you understand three things: moisture, acclimation, and movement. Miss any one of those, and problems show up fast.

Mistake #1: Skipping the Installation Instructions

This is the fastest way to void a warranty.

Every flooring product has rules—moisture limits, adhesives, trowels, expansion gaps, and acceptable humidity ranges. If you disregard even one of these rules, the responsibility for repairs usually falls on you and your contractor.

How to avoid it:
All instructions are available as PDFs on our website. You should print out two copies and provide one to your contractor. Some contractors assume they know how to install a floor and don’t take these instructions seriously. This is a major mistake. But seasoned contractors know that each manufacturer has different rules for installing their floor.

Always read the installation guide before you begin. That’s it. Thirty minutes now can save you thousands of dollars later.

Mistake #2: Not Sealing Subfloor Moisture

This error causes more damage than almost anything else.

The most common source of moisture related flooring problems can be located in the groundwater and in the ambient air. (This excludes the once-in-a-decade leaks in your basement walls or overflowing toilet, sink, or bathtub.) When water in the ground evaporates, it rises into your concrete slab, your crawlspace, and eventually your flooring. While humidity in the air can condense on cold surfaces, creating moisture on flooring, it typically does not cause as many problems as moisture underneath the subfloor.

If that moisture isn’t blocked, it can lead to cupping, buckling, dark stains, and mold.

Manufacturers' installation guides always describe exactly how much moisture is allowed. Typically, in concrete subfloors, they recommend moisture vapor emissions not to exceed 3 lbs/1000 SF over a 24 hour period or 8-12% in wood subfloors.

How do you test for moisture deep inside your concrete or plywood subfloor?
You can’t just look at the floor and assume that a dry surface means that it's dry inside. Manufacturers will recommend the type or brand of measuring tool to use. Typically a handheld moisture meter (available at most rental stores or available online) or a calcium chloride test that you can do yourself. Skipping this step is a gamble.

How to block moisture vapor: (General rules)
Next, manufacturers will recommend what type or brand of vapor barrier to use. These are usually made of 6mil polyethylene or vinyl sheets and provide a perm rating of 0.1. This makes them a Class 1 vapor barrier, which is the best rating recommended for most floating floors. For glue-down applications, epoxy adhesives have been traditionally employed. However, now there are safer zero VOC waterproof adhesives that provide excellent moisture control.

Nail-down hardwood and bamboo flooring over plywood subfloors requires a different type of underlayment called a vapor retarder. These have Class II perm ratings (.46 to .712 perm) because they allow some breathability.

Can I seal my concrete or wood subfloor with a sealer?
While concrete and wood sealers do an excellent job of sealing moisture, most manufacturers don’t accept them for warranty purposes because there is no way to verify how well they were applied or how long they will last. These sealers can be used in addition to vapor barriers if you never want moisture problems and want your subfloor to be 100% moisture free for decades.

What type/brand of vapor barriers are recommended?
For plywood/OSB subfloors, we recommend our QuietWalk Plus underlayment. It features a specialized vapor barrier that wicks moisture away from the subfloor. Our Silicone Vapor Shield is a semi-permeable membrane that blocks moisture even with thousands of nails penetrating through it. Our natural cork underlayment can also be used as a vapor retarder over plywood subfloors. Only one of the above is needed.

For concrete subfloors, for all types of floating floors — 6-mil poly vapor barrier; Moisture Block Pro or QuietWalk Plus is recommended.

For glue-down floors — Taylor Ironwood (for hardwood and bamboo) or Taylor Resolute (for cork) — both of these adhesives act as vapor barriers; no other items are needed. See the manufacturer's installation instructions for more details. Concrete must be clean, flat, cured, and tested for moisture. Please use the manufacturer's specified adhesive and trowel, work in small sections, leave appropriate expansion gaps, and clean up any misplaced glue immediately.

Mistake #3: Ignoring Crawl Space Moisture

Crawl spaces are one of the most common—and most overlooked—sources of flooring problems. Warm, humid air enters a cool crawl space, moisture condenses, and that moisture moves upward into the floor. The top of your floor stays dry. The bottom does not. That imbalance causes cupping.

How to avoid it:
Crawl spaces, or any unconditioned space, need proper ground vapor barriers, sealed seams, adequate clearance, and ventilation or conditioning per local code. If the ground below your home is wet, your floors will eventually be wet too because moisture always rises.

Crawl spaces should have a 6-8 mil black poly vapor barrier applied to the dirt below them. In addition, the suspended flooring should have a 6 mil vapor barrier stapled to the bottom of the floor joists, ideally with insulation between the joists. Local building codes will specify the required ventilation, if any, as well as recommendations for insulation and vapor barriers.

Mistake #4: Improper Acclimation

Natural flooring products made from wood, cork, Marmoleum and bamboo all respond to humidity. They always have and always will.

Acclimation refers to the process of allowing these materials to reach moisture and temperature equilibrium with the installation environment. When new floors aren’t acclimated properly, you’ll see shrinking, cupping, gapping, or what’s often called “dry cupping” from turning HVAC systems off after installation.

How to avoid it:
Acclimate the flooring in the rooms where it will be installed, not in the garage. HVAC should be running at a normal temperature (60-80°F) and humidity (35% to 60%) for at least 48 hours before acclimation begins and stay on afterward. Most floors need a minimum of 3 days. In exceptionally dry or humid climates, 7–14 days is safer. The installation guidelines are always very clear about the required time frames and storage requirements.

Open the boxes if required, allow airflow, and never acclimate directly on concrete. Moisture doesn’t announce itself—it sneaks up from below. Note: Some manufacturers, such as Kahrs, do not require acclimation.

Mistake #5: Forgetting to Leave Expansion Gaps

Floating floors are generally more stable than solid wood floors. However, because they are made with natural materials, they can expand and contract in reaction to temperature and humidity. That movement adds up across areas greater than 25 linear feet. Depending upon the type of floor, there are different requirements for expansion gaps around the perimeter or between two different types of floors. This is always spelled out in the installation guidelines.

When humidity drops or spikes, floating floors can shrink, gap, or push against each other and buckle at doorways, floor registers, toe kicks, or around other obstructions. They can also squeak. Also, make sure that base moldings are not pressed down so tightly onto the flooring that they prevent movement.

How to avoid it:
Control your indoor humidity year-round between 35% - 60% with your thermostat, or add humidifiers or dehumidifiers as needed. If this is not possible, glue-down installation is the safer choice. Glue-down floors don’t have run-length limits, and they handle seasonal movement more gracefully. When in doubt, choose stability over convenience.

Smaller rooms require smaller expansion gaps than larger rooms. Rooms with excessive moisture or dryness may require larger or smaller gaps. Changing the direction of how the floor is installed from lengthwise in a hallway, for example, to crosswise in a bedroom usually requires a T-molding or threshold to allow proper expansion.

Mistake #6: Letting Glue Dry on the Finish

Flooring adhesives are incredibly strong. If some accidentally gets onto the floor surface, it can permanently damage the finish.

Those cloudy spots you sometimes see? That’s not dirt. That’s damage to the finish.

How to avoid it:
Clean the adhesive immediately while it is still wet using approved adhesive remover wipes. Never use mineral spirits or harsh solvents—they can strip the protective topcoat from your floor.

Mistake #7: Using the Wrong Fasteners

Most floating engineered floors such as cork, Marmoleum, GBS Waterproof Hardwood, Kahrs and some GBS Strand Bamboo flooring do not require any fasteners. They click together side to side and float over the subfloor. However, most tongue and groove ¾” solid hardwoods or bamboo require nails or cleats to hold them down.

Also, different wood species have different hardness ratings. As a consequence, the nails (aka cleats) and tools required by the manufacturer may differ. Strand woven bamboo, for example, is much harder and denser than typical oak flooring. That’s a good thing — but it also means it needs the right tools and fasteners.

Using the wrong cleats (nails) or incorrect air pressure in your pneumatic nailer can cause dimpling, split tongues, or surface damage. As you begin, ensure the nailer is seated properly (make sure the installer is not leaning the nailer forward, and is using the correct adapter plate).

How to avoid it:
Refer to the installation instructions and set your PSI carefully, and test on scrap boards before committing. Typical hardwood uses 15 or 16 gauge nails, while strand bamboo and some Brazilian hardwoods require 18 gauge cleats. Take your time. Dense material rewards precision.

Mistake #8: Forgetting to Use Furniture Pads and the right cleaners

Many modern hardwood, bamboo, cork and Marmoleum floors use UV-cured acrylic urethane finishes. They’re durable — but not invincible. They come with longer wear warranties, but can still be scratched.

Mineral spirits, turpentine, and acidic cleaners can permanently dull or cloud the surface.

How to avoid it:
Stick with manufacturer-approved cleaning types and brands. If you’re unsure, test on a scrap piece first. Most of our neutral pH floor cleaners work well on any type of flooring.

Use felt pads or sliders (available at most hardware stores) under all furniture legs and casters to spread the load and protect your floor. Once a finish is damaged, cleaning won’t fix it. Use a Tibet Almond Stick or wax pencils to fill minor scratches.

Mistake #9: Playing with Fire

Fireplaces, gas stoves, and even radiant heated floors will dry out your floor. As a consequence, the floors will shrink, creating large gaps, cupping, or buckling. This effect is even more true when the heat source is very close to the flooring.

How to avoid it:
For fireplaces or wood stoves, consider an apron, such as tile or stone, that is at least 18” wide around the entire base. Be sure to leave expansion gaps around the perimeter and, of course, monitor the room's humidity to keep it between 30–60%. Avoid shocking a new or cold floor; gradually increase the heat when the floor is new or at the start of the heating season.

For radiant heated floors with electric or hydronic heat sources, check the flooring manufacturer’s installation guidelines to make sure the floor is warranted over radiant heat and what maximum floor temperature is allowed. Remember that the flooring temperature is the critical point, not the boiler or water temperature. We recommend using an infrared heat gun (available at hardware rental stores or online) to check various areas of your room to ensure the heat does not exceed the maximum. A heat gun is also a good way to double-check that the heat is evenly distributed throughout the room.

Mistake #10: Not preventing moisture in a bathroom

Full bathrooms, especially with kids or pets, require special attention to moisture during and after installation. Powder rooms are less susceptible, but still require preventative measures.

Most obvious problems occur when a toilet, sink or tub overflows. What is less obvious are the effects of steam, acidic cleaners, hidden leaks, and humidity above 60%. These all can shorten the life of any floor if not treated properly and immediately.

How to protect your bathroom floor from excessive moisture?
Be sure to:

Dry the floor immediately after leaving the shower or tub
Ventilate aggressively by opening windows
Leave the ceiling or window fan on for 10-15 minutes after you leave the bathroom
Inspect regularly.

For floating floors, be sure to add a bead of caulk under the edges of the perimeter to prevent spills from getting under the floor.

For glue-down floors, ensure you apply the appropriate amount of adhesive by using the right type of moisture-resistant adhesive and use the correct trowel size.

Waterproof flooring products, such as GBS Waterproof Hardwood Click, Marmoleum Click Cinch Loc Seal, and Waterproof Cork, protect against water spills from above, but they are not floodproof. No one warrants their flooring for floods.

Final Thoughts

They move. They breathe. They respond to moisture. This is not a defect—it’s physics.