Plywood is just one of the strongest and most versatile building materials. It is also extremely versatile, and can be used for many applications. It’s important to make sure that plywood lasts as long as possible when you are using it outdoors.
Outdoor woods need extra special care because they’re exposed to the elements all year round. You don’t want your beautiful deck or patio furniture rotting away before its time!
The best thing to do is seal your plywood using a good quality exterior grade wood finish. This will protect it from the elements and make sure that you get maximum value out of all your DIY home improvement projects
However, the sealing process is not as straightforward or easy as it seems. Don’t worry though, we’ll give you a step by step guide on how to seal plywood for outdoor use and ensure that your project lasts as long as possible.
Table of Contents
What does sealing do?
In the construction industry, sealing is a process of waterproofing to protect the wood and prevent moisture from seeping into and damaging it. When painting or staining plywood, the sealant goes on before the paint or stain. Painters and contractors use a variety of sealants for different purposes, such as natural oils to create an antimicrobial barrier, water-based products which dry quickly, or solvent-based products which provide a more durable coating.
Benefits of Sealing Plywood
There are a number of great benefits that you get from sealing plywood for outdoor use, including:
Prevention of Rotting
Wood can quickly rot when left exposed to the elements without a protective coating. Sealing plywood for outdoor use will prevent water from reaching the wood, which will prevent it from rotting.
Prevention of Insect Infestation
Wood can be home to many insects and bugs including woodworm, termites, and cockroaches. Sealing plywood for outdoor use will prevent these pests from getting inside your wood and destroying it.
Simple Cleaning
Sealing plywood for outdoor use will make cleaning a breeze. Without the protective coating, dirt and debris can get stuck in the wood and cause unsightly stains. Once sealed, simply hose the wood down to get it clean!
Increase Value
By sealing plywood for outdoor use, you can increase the overall value of your home. Your deck or patio furniture will be safe from rotting and look great for many years to come.
Sun and moisture protection
Sealing plywood for outdoor use will protect the wood from sun damage and moisture. This is great for people who live in cold, wet climates where moisture can seep into unprotected wood.
The only downside of sealing plywood for outdoor use is that it darkens the color slightly, so if you are looking for a lighter finish, then it may be wise to choose another option.
What is the best plywood to use outdoors?
There is a variety of plywood that is suitable for outdoor use, so you can choose the best one depending on your budget and personal preference. There are several different types of plywood used outside, including CDX, marine-grade, pressure-treated, OSB, and T-11. Each type of plywood has its own benefits and it’s best to choose the option that suits your specific needs.
CDX Plywood
CDX Plywood is a good choice for outdoor use because it is made from hardwoods with an exterior grade glue, making it incredibly durable against rot and moisture damage. It also features alternating layers of softwood which can be left unfinished or painted immediately. Because it is a plywood, you will have to paint the exterior of your project after sealing it for outdoor use, but this can be done with an exterior grade latex paint that won’t fade easily over time.
Marine-grade plywood
Marine-grade plywood is another great option because its glue contains waterproof ingredients and resists swelling from weather. It can be left unfinished or painted immediately and it is a great choice if you want the natural look of untreated wood.
Pressure-treated plywood
Pressure-treated plywood contains advanced chemicals that protect against rot, insects, water damage, stains from mold or mildew growth. This type of plywood should also be sealed for outdoor use before being used in your project.
OSB plywood
OSB plywood is a good choice for outdoor use because it is extremely strong and less susceptible to warping, shrinking, or swelling from weather. It does not require sealing but can be painted immediately after purchase if you choose to do so.
T-11 plywood
T-11 plywood contains advanced chemicals that resist water damage, rot, insects, and mildew. It can be left unfinished or painted immediately and is a great choice for outdoor projects where you want the natural look of untreated wood.
How to seal plywood for outdoor use: A step-by-step guide
If you are looking for a great way to seal plywood, here are some steps you can follow to ensure the best results every time.
Step One: Prepare the wood surface
If you are painting, sand the wood in preparation for painting. This will ensure that the paint properly adheres to the surface of your project and you won’t have any rough or bumpy areas to contend with.
Step Two: Wipe the wood down
Wipe your plywood for outdoor use completely clean using a damp cloth or sponge and allow it to dry before continuing on. If you are painting, this should be done after sanding but prior to moving onto Step Three.
Step Three: Add a clear coat
Add a layer of polyurethane over your plywood for outdoor use using a high quality brush or roller. This will protect it from moisture, sun damage and other environmental factors that could cause the wood to warp, shrink, swell, rot or mildew.
Making sure you seal plywood for outdoor use is a great way to protect your wood from the elements and add an extra layer of durability.
There are three common ways to seal outdoor plywood.
If you want to use plywood for outdoor purposes for a long time, then it is essential to waterproof plywood. It should be done to protect your wood from any exterior damage.
There are three ways to waterproof plywood: Polyurethane varnish, Spray Paint and oil finish.
Polyurethane varnish
Polyurethane is the most effective method for sealing plywood. It is an easy way to protect the wood from all types of damage, but it also gives your project a beautiful finish. This is the best way to seal plywood. Follow the process on how to seal plywood using polyurethane varnish below.
First, you have to protect the floor from splashes. This will not only save your project but also give a finished look.
Second, you have to sand the plywood. It is necessary for it will remove all rough surfaces, which can lead to splintering in the future.
Third, apply the first coat of polyurethane and wait for it to dry.
Fourth, sand it with fine-grit paper. You have to sand it lightly.
Fifth, apply the next coat of polyurethane and let it dry completely before you add another coat.
Sixth, sand the wood again and wait for it to dry completely before applying a coat of polyurethane varnish with a brush.
Seventh, apply the last coat of polyurethane varnish and let it dry for 24 hours before you use your project.
Oil finish
The most simple way to seal plywood is oil finishing. It also protects the wood from exterior damage, but it doesn’t give your project a beautiful finish. Follow the process on how to oil finish plywood using linseed oil below.
First, you have to apply the first coat of polyurethane varnish and let it dry for 24 hours before adding another coat. Apply two coats if necessary according to its instructions on the label.
Second, you have to sand the plywood thoroughly. It is necessary for it will remove all rough surfaces, which can lead to splintering in the future.
Third, apply linseed oil over your project and let it dry completely before applying another coat of finish.
Fourth, repeat step three until you get the desired look on the wood surface.
Finally, you have to wait for at least one week before using your project.
Spray paint
This is the easiest way of finishing plywood but not as effective as oil finish or polyurethane varnish. You just need to apply spray paint on the surface and let it dry completely before adding another coat if necessary. It does not increase the longevity of your plywood.
Follow these steps on how to seal plywood using spray paint:
First, protect the floor from splashes. This will not only save your project but also give a finished look.
Second, sand the plywood thoroughly with fine-grit paper to remove all rough surface which can lead to splintering in the future.
Third, apply the first coat of spray paint and let it dry completely before adding another coat if necessary. You have to wait for at least one hour between coats according to its instructions on the label.
Fourth, sand it with fine-grit paper again after waiting for an hour. It will remove excess coating from the surface which can lead to unevenness in the next step when you start painting your project using a brush or roller applicator.
Fifth, start applying polyurethane varnish with a brush or roller as per your liking until you get the desired look on the wood surface. And finally, wait 24 hours before using your project fully.
FAQ’s About How to seal plywood
What can I put on plywood to make it waterproof?
You can put waterproofing sealer, spray paint and oil finish on plywood to make it waterproof.
How to seal plywood for a garden bench?
You can use polyurethane varnish. Apply two coats and sand it between the first and second coats before adding another one.
How to seal plywood for an outdoor coffee table?
You can use spray paint and oil finish. Oil finishing gives you a smooth appearance, but it is susceptible to exterior damage.
Can you use PVA to seal plywood?
Yes, you can. Just make sure that the PVA is compatible with other finishes (oils or water-based) before applying it to your project.
Is plywood waterproof?
Plywood is not inherently waterproof. It needs to be treated before you can use it in outdoor projects or exposed areas. You have to seal the wood with polyurethane varnish, oil finish or spray paint before using your project fully.
Can wood glue be used as a sealer?
Yes, but it won’t last long. Make sure to use a water-resistant glue when using plywood in outdoor projects or exposed areas.
What is the best way to seal my plywood?
You have three ways of sealing your project which are polyurethane varnish, oil finish or spray paint. Oil finishing gives you a smooth finish but is susceptible to exterior damage while polyurethane varnish protects the wood from exterior damage with no compromise on its appearance, but it needs two coats before applying another one which can take up more time compared to the oil finishing and spraying process.
Conclusion
Now, you know how to seal plywood for outdoor use after reading our guide. You can use any of these methods to seal plywood.
However, Above mentioned methods and tips will help you to seal plywood. But, you have to follow the instructions on the label before using them. If you do not use it correctly then there are chances of damage or destruction in your project.
We are confident you know very well what you are doing when it comes to sealing plywood and that you will be able to seal your wood like a pro!
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