Plywood is well known in the building industry for its strength, versatility, and durability; however, one of the most common problems that many builders, designers, and homeowners face is the bending or warping of plywood sheets. The bending of plywood can lead to alignment problems in furniture and curved panels over a period of time, so it is very important to understand why plywood bends so that you can help to ensure that it will perform well throughout its life cycle. Bending of plywood is not always due to a defect; there are many environmental factors, manufacturing differences, or intentional design uses that may cause this problem. To make proper material and design decisions, it is essential to understand both why plywood bends and when this will be an issue, and how to effectively control the bending.

Quick answer

The most common reason for the bending or warping of plywood panels is due to an imbalance in moisture content, uneven moisture content, improper storage of the plywood, or environmental changes. Plywood is made from layers of real wood and is subject to movement due to changes in humidity or temperature; this can cause plywood to expand or contract, which leads to bending. By learning why plywood bends, builders and designers can help to prevent structural problems from developing and will also be able to help in the design of controlled bending of plywood for use in furniture or in interior applications

Table of contents

• Quick Answer
• What is Plywood
• Understanding why plywood bends
• The primary reason why plywood will bend is an imbalance
• Understanding types of bending in plywood
• The benefits of bending when designing
• When bending is considered a problem
• How to prevent plywood from bending
• How to fix bent plywood
• Selecting the right plywood to minimise bending
• Practical advice for homeowners, interior designers, and architects
• Why Royale Touche plywood has better performance than others
• Conclusion
• FAQs

What is Plywood

Plywood is a manufactured product that consists of thin strips (veneers) of wood that are glued together in alternating grain patterns. This process of glueing the grain in opposition to one another is specifically done to prevent the wood from swelling and shrinking when exposed to moisture and humidity. Although plywood has an engineered design which provides less movement due to moisture compared to solid wood, it is still made from a natural product, therefore, it will absorb moisture and be affected by moisture and pressure depending on the way that it is manufactured.

Understanding why plywood bends

The reason that plywood bends is based on the different amounts of moisture and stress on either side of the plywood panel, thus causing it to expand or swell. The level of expansion and/or swelling generates an internal stress or tension, causing the plywood panel to twist or warp.

The primary reason why plywood will bend is an imbalance

The reasons that plywood bends can be determined by understanding how the wood reacts to its environment. Plywood is designed to be stable; however, if the environment is extreme or inconsistent, it can still bend. If you understand the different causes of plywood bending, you will be able to better understand how to prevent or fix the problem if it occurs.

Moisture imbalance

Unequal moisture absorption is the leading cause of warped plywood. Humidity on one side of the sheet will cause it to expand, while the opposite side has no moisture and remains unchanged. The resultant warping of the plywood gives rise to the bending of the pull or curve shape. Therefore, the environments in which plywood is most often bent are kitchens, bathrooms, or areas near the coast due to the fact that they typically contain a large amount of water.

Improper storage

The conditions under which sheets of plywood are stored are also a leading cause of the sheets' bending. If sheets are stored in a vertical position without adequate support (e.g. using spacers) and/or are placed on uneven surfaces, this can create stresses that will lead to the bending of the sheets. Continuing to expose the plywood to either direct sunlight or wet ground conditions will only contribute to the problem.

Uneven load or pressure

Bending in plywood can be caused by placing an excessive amount of weight in a specific area of the plywood. The plywood will also bend when the underlying structure does not properly support the plywood. Also, if the plywood sheet is thinner than required for the application or use for which it was used, then this will result in plywood bending.

Manufacturing quality

Plywood sheets can also be manufactured to different standards by using various grades of material. Sample characteristics of a lower-grade plywood sheet are:

• The veneer layers do not have a consistent thickness.
• The bonding between the sheets has not been completed to the manufacturing standards of the bonding agents or adhesives.
• Additionally, the layers have a varying amount of thickness.

Because of the above-mentioned factors, lower-grade plywood is more likely to develop a curve or bend, and this is a further reason to use quality plywood when determining the reason why plywood bends.

Temperature changes

Rapid fluctuations in the ambient temperature will result in expansion and contraction of the plywood sheet, thus bridging the layers together physically and developing forces or stresses within the plywood panel. As such, temperature variations and fluctuations can cause or contribute to the bending of plywood under certain conditions.

Understanding types of bending in plywood

Not all bending is the same; therefore, understanding the various types will help assess the effect of bending.

• Warp: The surface has an uneven curve
• Bow: The length is bent
• Cup: The edge has risen, while the centre is lower than the edge
• Twist: The corners have become out of alignment

Each of these types of twists shows how plywood has different ways to bend according to what has happened to it.

The benefits of bending when designing

As one would suspect, many times, the bending of material has a disadvantage. However, there are also instances where controlled bending is actually considered an advantage.

• Curved edges of furniture
• Decorative panels
• Modern architecture

So, knowing why plywood bends allows the designer to use this knowledge creatively instead of trying to avoid material that bends.

When bending is considered a problem

Bending will be a problem when it affects either the use (functionality) of the item or disturbs how the furniture or structure is seen. Some examples would be:

• Cabinet doors that are not aligned
• Uneven shelves
• Structural instability

This is where understanding why Dollywood bend is critical in being able to prevent and fix these issues.

How to prevent plywood from bending

Preventing plywood from bending contains three elements: moisture, load, and installation conditions. Each of these elements must be handled properly to avoid internal stresses forming in the plywood.

• Store plywood flat and provide full support
• Keep equal amounts of moisture on both sides of the plywood
• Use proper thickness for the intended application
• Seal all edges and surfaces
• Select a suitable plywood grade

How to fix bent plywood

The approach taken to fix bent plywood is determined by the reason for the bend and the extent of the bend. The main goal of straightening bent plywood is to relieve some of the internal stresses to achieve a condition of balance, rather than just applying force to put it back straight.

• Moisture balance (for slightly warped)
• Pressure application (for moderately warped)
• Provide supplemental support (if the plywood is installed)
• Replacement is the solution (if the plywood is severely damaged)

Key point: The only way to alleviate the bending is to address the source of the bending, being either moisture, weight or the quality of the plywood.

Selecting the right plywood to minimise bending

Selecting the correct type of plywood to minimise bending issues is critical.

• Marine plywood is best used in areas subject to moisture
• Boiling waterproof plywood is a great option for high humidity
• Calibrated plywood provides consistent thickness
• Termite and borer-proof plywood ensures durability

Selecting the appropriate type of plywood based on how you want to use it is critical to your project and will determine how often and why plywood bends.

Practical advice for homeowners, interior designers, and architects

For homeowners

• Choose plywood for the specific application
• Choose the appropriate thickness
• Provide adequate ventilation
• Check early signs of bending
• Store plywood properly

For interior designers

• Design for expansion/contraction
• Use calibrated plywood
• Use proper techniques for curves
• Match laminates/veneers correctly
• Allow slight tolerances

For architects

• Integrate moisture control
• Specify correct plywood grades
• Plan load distribution
• Avoid contact with damp surfaces
• Select plywood based on the climate

Why Royale Touche plywood has better performance than others

Addressing how and why plywood bends, the quality will have a direct result on how plywood performs. Royale Touche plywood has been engineered to perform with superior stability/performance.

• Higher level of manufacturing
• Moisture-resistant, high-quality interior core
• Calibrated precision
• Long-term durability

Royal Touche is the best option to minimise problems resulting from bending plywood when used in applications in the "real world".

Conclusion

Users of quality furniture/interior design need to know how and why plywood bends. Bending can be caused by moisture, pressure or environmental issues in plywood; however, when you use the correct materials, store plywood properly, and follow the logical application procedures for use, we should be able to eliminate or significantly reduce the number of times that we experience bending in our furniture/interior design applications. Using quality plywood, following best practices will result in your furniture having the aesthetic appeal and the stability you desire from your interiors.

Frequently asked questions

1. Why does plywood bend?

Plywood bends because of moisture, pressure and/or environmental issues that cause it to expand and contract.

2. Can I fix bent plywood?

Yes, you can fix slightly bent plywood by using the combination of moisture, pressure and/or support; however, severely warped plywood must be removed and replaced with new plywood.

3. Does fully waterproof plywood still bend?

Fully waterproof plywood has a greater resistance to bending than other types; however, if treated improperly, it can also bend.

4. How can I prevent plywood from bending?

Proper storage, balanced exposure, sealing and quality plywood will help to minimise the likelihood of plywood bending.

5. Which plywood is the best to prevent bending?

For the best plywood to use to minimise bending, choose high-quality plywood such as Marine Plywood or Boiling Waterproof Plywood.

Related Blogs

How to Prevent Mold on Plywood?

How to Check Plywood Quality

Explore Other BlogsExplore Other Blogs