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Selecting and Using Waterproof Plywood Panels

 

What is waterproof plywood?

Waterproof plywood is a moisture resistant material that many people use for various purposes in their home. It is great for outdoor usage, as it is resistant to various weather conditions, such as rain, sleet, snow, etc. It also works great for subfloors (levels underneath the "actual" floor), since it can keep moisture from the ground out of the floor.

Ways to Waterproof Plywood

Waterproof plywood panels can be purchased at almost any hardware store or home improvement chain (ex. Lowe's, Home Depot, etc.), or online. However, some people may choose to waterproof their own plywood panels because of cost, enjoyment of being hands on, or whatever the reason may be.

There are several ways that people can waterproof plywood on their own. First of all, it is important to fix the defects on a piece of plywood to the best of the individual's ability. This means that the plywood should be sanded, cracks should be filled in, etc.

The best way to waterproof plywood is using a waterproof paint, stain, or sealant on top of the plywood panel. These items can also be purchased at local hardware stores, home improvement chains, and online. Once the plywood has been thoroughly sanded and cleaned to remove any defects or leftover non-waterproof stains or paints, the sealant (which can also be mixed with an epoxy paint) can be applied. Depending on the specific type of wood and usage intended, multiple layers may be required. In general, though, two or three layers will serve a fine purpose.

plywood panel on sawhorses

On a side note, waterproof glue is available when connecting two or more pieces of plywood together. This helps to fortify the construction even further along with the waterproof layers of sealant, paint, stains, etc.

ABX, ACX, ADX Plywood- What do the letters mean?

The letters that label plywood refer to the grade and type of glue that is used. Grades A, B, C, and D are used by the American Plywood Association (APA) to indicate the quality of the plywood panel. When two letters are present (ex. AB, AC, and AD), the consumer can tell that two panels are glued together, with each side being a different quality of plywood. "X" stands for exterior grade resin glue, not exactly waterproof but more like higher quality.

Starting with Grade A, each consecutive letters indicates more faults in the plywood panels. These faults, or defects, include cracks, splits, knots, edge gaps, etc. Grade A plywood has very few of these defects, and those that it does have are fixed before selling. For example, knots can be removed and filled with better looking, more durable wood patches. Grade B has more defects than Grade A, but still has relatively few defects and is still considered high quality. Grade C and Grade D plywood have more initial defects than Grade A and Grade B plywood. Several defects may also be left as is, without repair.

The "X" in this classification system refers to the type of glue that is used. Grade X plywood glue can be exposed to moisture with little or no damage. However, it is not water or weather resistant, so it is less durable than glues that are.

What can these types of plywood be used for?

Plywood that has a Grade A side and a lower grade side is generally used in decorative purposes, since it is more expensive. Lower grades are more cost effective, but less durable than higher grades. ABX, ACX, and ADX plywood, depending on the type of exposure that they will receive, may be used for boat construction, flooring, etc. The X, again, also indicates that these can be exposed to some moisture, which is why many people decide to use these types for exterior purposes.

Where can they be purchased?

Plywood grades do not correlate to an exact species of plywood. Therefore, species availability does not affect purchase location of these panels. For the most part, many different grades of plywood panels can be purchased at local hardware stores, home improvement and hardware chains (ex. Lowe's and Home Depot), or even online through these chains or direct from the manufacturer. Again, cost is an important factor that plays a role. If it is not essential that one side be of high quality, purchasing ACX or ADX versus ABX is a great way to save money.

Other Tips for Waterproofing Plywood

Again, depending on the type of wood and purpose intended, multiple layers may be required. Furthermore, it is important to maintain the waterproof sealant. Plywood exposed to harsher conditions, such as panels used on a boat or outdoors, may need new layers to be applied every few years, or even several times in a year.

Safety is also an important factor when waterproofing one's own plywood. Sanding and cleaning plywood can lead to chips or splinters. Safety goggles and gloves should be worn at all times. These pieces of equipment are also important in the waterproofing process since the materials used could be toxic.