Interior Vs. Exterior Plywood (Pros & Cons) - Woodworking Trade (2024)

What Is Plywood?

Plywood comes in the form of boards of different thicknesses. It consists of several thin layers of wood veneer bonded with an adhesive. The thickness of the plywood varies in line with the number of layers that make it up.

The direction of the wood grain of successive veneer layers lies at right angles to each other. This arrangement gives the plywood its characteristic strength.

The plywood’s quality and strength will also depend on the type of wood from which the plywood is made. Manufacturers may also treat plywood with chemicals and reagents to make it resistant to fire, water, termites, heat, and so on. Plywood is one of the easiest types of wood to work with.

Interior vs. Exterior Plywood

Plywood is a cheap, strong, and versatile material that we use in many different woodworking projects. We categorize the wood according to its end-use.

Depending on strength and resistance to water, we have two main types – exterior plywood and interior plywood.

Exterior Plywood

Exterior plywood is weather-resistant, and hence we can use it outside where it will be exposed to the elements. The wood is more robust, and the waterproof glue binds the layers together. Exterior plywood withstands strong winds and has a fair degree of resistance to rain and extreme weather.

Exterior Plywood Pros

Here are a few pros of exterior plywood:

Visual Appeal

When we apply a suitable finish to exterior plywood, we find it visually appealing. In a survey conducted in 2015, 90% of respondents admitted to preferring wood which also included plywood for outside décor.

Good quality plywood looks good even if it is left as it is because of the grain patterns. Plywood, like other types of wood, imparts a natural, warm look.

Strong and Durable

Although exterior plywood, like all other varieties, comes in thin sheets up to a maximum of perhaps ¾” thick, it is incredibly strong thanks to the cross-graining. It helps to distribute the load across the surface of the wood.

Dimensional Stability

Plywood has a high level of dimensional stability due to cross-graining. This characteristic makes exterior plywood an ideal choice for base structures in construction. It also shows considerable resistance to change shape due to high moisture or fluctuating temperature.

Cost-Effective and Available

You can procure exterior plywood easily, and it costs a fraction of other types of construction wood, brick, concrete, or steel. You can buy exterior plywood in any timber store.

Eco-Friendly Material

Plywood is one of the most eco-friendly materials you can get. The quantity of wood used to produce plywood is less than solid wood, where we use 100% of the wood. You can reuse exterior plywood multiple times if you are careful and use less glue for easy replacement. You would do well to check with your supplier if the plywood being sold to you comes from sustainable wood.

Cons of Exterior Plywood

There are a few downsides to exterior plywood. Here are the main cons that come to mind:

Higher Embodied Energy Needed to Produce it.

A higher level of embodied energy goes into making plywood sheets than other timber products. Embodied energy means the total energy consumed in harvesting, transporting, processing, and delivering the product to the end-user.

Limited Thermal Insulation

Exterior Plywood provides lower levels of thermal insulation as compared with solid wood. Hence, you can expect limited protection from heat and cold from exterior plywood.

Low Breathability

The extent of breathability of exterior plywood can vary according to the grade and thickness of the material. Nevertheless, breathability is relatively low as compared to that of solid wood.

You can increase exterior plywood’s breathability if used for cladding by adding sarking or providing vapor cavities. You would probably need to do this for buildings along the coast that are prone to condensation.

Adhesive Toxicity

The glue that manufacturers use to bond the layers of plywood together is frequently toxic. The common additive in these glues is urea-formaldehyde, a known carcinogen and a harmful substance to the environment. Plywood glue can contain other toxic substances as well.

Low Fire Resistance

You can get varying levels of fire resistance with exterior plywood. But generally speaking, you can only get poor to average fire resistance from it compared to other types of wood. It is common for builders to combine exterior plywood with other materials like brick or steel to increase fire resistance.

Interior Plywood

We use interior plywood for all sorts of indoor applications. This type of plywood doesn’t have resistance to water or the elements. You can use interior plywood for flooring but not for bathrooms and kitchens where exposure to moisture is high. Using exterior plywood would be the best choice for such applications.

Pros of Interior Plywood

Here are some of the top benefits you can expect to get from using interior plywood:

Great Strength

It is one of the strongest forms of wood as compared to solid wood. You will find it almost impossible to crack or shatter plywood thanks to the cross-grained structure. It ensures that the load gets distributed evenly across the surface of the wood. The glue that bonds the layers together further adds to the strength of interior plywood.

Durability

In terms of durability, interior plywood lasts comparatively longer than solid woods, prone to damage from misuse. The high resistance to impact also adds to its durability. Hence, you may find that interior plywood furniture lasts longer than furniture made from solid wood in many cases.

Appearance

We all prefer wood to other materials for its attractive appearance. Plywood comes in a variety of shades, hues, and unique wood grain patterns. Particularly with interior plywood, you can get some attractive-looking sheets to make furniture and shelves that are aesthetically good to look at.

Light Material

Although the sheets come in large sizes, interior plywood is relatively lighter than solid wood and easier to transport. This characteristic makes plywood a favored material for making indoor furniture.

Cost-Effectiveness

Interior plywood, like all other varieties of plywood, comes from less expensive wood. This considerably brings down the cost as compared to solid wood.

Available in Large Sizes

Unlike solid wood that is restricted to tree trunks’ dimensions, you can get plywood in huge sheets.

Environment-friendly Material

Interior plywood requires fewer trees to be cut down to produce it, giving it an edge of solid woods in terms of eco-friendliness.

Versatility

We use interior plywood in several applications like flooring, furniture, cabinets, doors, and shelves. It is easy to work with and quick to install.

Flexibility

You get different types of indoor plywood. You can bend the flexible variety if you have to line it up with curved ceilings or walls.

Cons of Interior Plywood

Although a beneficial form of plywood, there are some downsides to interior plywood that are worth noting:

Low Resistance to Water

The plywood layers can separate if you allow the plywood to be exposed to water for prolonged periods. You can remedy this to some extent by using boiling waterproof (BWR) grade plywood.

Tends to Bend or Sag

If you use longer pieces for benches, long panels, or even big doors and windows, the plywood can bend in the middle.

Difficult to Judge the Quality

Although you can make out an interior plywood sheet’s outer appearance you don’t know what’s inside. Manufacturers sometimes mix inferior quality flawed wood for the inner layers. You will not be able to make this out.

You Need to Cover it.

We have to cover commercial-grade interior plywood has with laminate or other wood veneers. You do not need to cover surface of solid wood with anything except some suitable varnish or lacquer for it to look beautiful.

Conclusion

You can use plywood in any of your woodworking projects for satisfactory results. Suppose you know the difference between exterior plywood and interior plywood, you can make the best of these materials and get the most out of your woodworking projects from this versatile form of wood.