Does Plywood Expand and Contract in Winter and Summer

Plywood is a very popular and commonly used building material. It consists of 3-4 layers of wood veneer bonded together with special glue. It has become a basic need of every artisan and woodworker due to its strength, durability, and affordability.

However, like many other wood-based products, plywood has some queries about its immunity that should be solved first.

One of the questions always arises: Does plywood expand or contract?

The simple answer is “Yes”.

However, it is necessary to find all the reasons and solutions to minimize the effects of contraction and expansion.

So, today, in this article, I will explain all the reasons behind the plywood expansion and contraction and the solution that can minimize its effects on it.

So, keep reading.

 

Composition of Plywood

It is necessary to understand plywood composition first, before analyzing the factors that cause plywood expansion and contraction.

Plywood is made of various thin sheets of wood veneer. These sheets are created from different types of trees, and every tree wood has special characteristics.

All the veneer sheets are layered one by one and composite with special glue under specific pressure. Different trees wood can influence the plywood’s overall properties, regarding its environmental changes.

 

Note: I have already written a detailed article about How plywood is manufactured step-by-step. Read it also.

Does Plywood Expand and Contract in Winter and Summer

Factors Affecting Plywood Expansion and Contraction Behavior

Below are some factors that affect the plywood behavior.

 

1- Adhesive’s variations

The use of adhesive material in the bonding of the layers is one of the most significant factors in plywood expansion and contraction.

Different adhesive materials have different levels of moisture resistance, which can significantly impact the behavior of plywood expansion and contraction when exposed to a humid environment.

For example, an adhesive material that absorbs more humidity can cause the expansion of plywood, while low absorption adhesive material can cause contraction.

 

2- Plywood and Moisture

It is a common thing. Where we live, moisture is always present in the atmosphere. And the moisture presence is the key factor for the dimensional changes in plywood.

By default, plywood absorbs and releases the moisture from its surroundings. When the humidity level increases in the winter, the plywood absorbs moisture and expands.

While in the summer season, plywood releases its moisture and contracts.

So, moisture is the key factor in the dimensional changes of plywood.

 

3- Temperature Effects / Variations

Temperature is another factor in the dimensional changes of any plywood.

It has reversible reaction effects on the plywood. Effects change with the changing of temperature.

Plywood expands with increasing temperature and contracts as temperatures drop.

This thermal response is essential to consider in the installation of plywood that is subject to temperature fluctuations.

However, this thermal effect also depends on plywood types, adhesive material, and veneer composition variation.

 

4- Grain’s Direction

Another critical factor is the grain direction of the individual wood veneer layers within plywood. Plywood is typically manufactured with alternating grain directions between layers, which helps minimize wood’s natural tendency to expand and contract along its grain.

When plywood expands or contracts, the opposing grain directions of the veneer layers can help stabilize the overall shape and reduce warping or twisting.

If the grain direction is the same in plywood manufacturing, it can cause expansion or contraction in the plywood.

 

5- Plywood Thickness

The thickness of plywood sheets can affect the value of expansion and contraction. Thicker plywood tends to be less responsive to environmental changes than thinner sheets.

Therefore, we should always choose the appropriate plywood thickness according to the required applications.

 

Does Plywood Expand and Contract in Winter and Summer

How to Minimize Plywood Expansion and Contraction

While there is no perfect method, but using these practical steps, we can minimize the effects of contraction and expansion.

 

1- Proper Plywood Storage

To minimize these effects, storing the plywood in a controlled environment is necessary. Remember, this environment should have stable humidity levels and moderate temperatures. Keeping plywood in a dry, well-ventilated area will help to maintain its stability, increasing its life and product value.

 

2- Sealants and Finishes

It is an effective way to control plywood expansion and contraction by applying sealing and finishing at the wood surfaces. Many quality finishes are available in the market, like paint, varnish, or polyurethane.

When we apply it on the plywood’s surface, it will work as a barrier to the moisture in the atmosphere. It can significantly reduce the extent of expansion and contraction, especially in outdoor exposure places.

 

3- Structural Considerations

In structural applications, proper installation is a technique that is very important to minimize the effects of plywood expansion and contraction.

For example, leave small gaps between plywood sheets to accommodate size changes.

Fasteners like screws and nails should be placed to allow for movement without causing splitting or cracking.

Engineers and builders are responsible for designing the structure to accommodate the allowance of expansion and contraction.

 

Conclusion

Understanding the behaviors is crucial when using plywood in various applications. Because, it can affect the performance and life of our projects.

I have explained all the factors that can affect our projects, and described the solutions to minimize the contraction and expansion.

Following the described methods, you can effectively minimize the effects of plywood expansion and contraction to ensure the durability and stability of your structures and projects.

Thank you for your time.

Best Wishes

 

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