Weatherproof Wooden Signs: 6 Step DIY Guide

blank wood sign hanging on tree
  • 3-5 hours
  • Intermediate
  • 50-200
What You'll Need
What You'll Need

A wooden sign is a charming little touch anywhere you put it, immediately creating a look of rustic appeal and DIY energy once it’s been hung up. But it can stop looking pretty after just one harsh season, which means you need to know how to weatherproof outdoor wooden signs to keep them looking nice o they can be enjoyed for many years to come.

Why Use Wood for Custom Weatherproof Outdoor Signs?

Wooden signs are a great crafty project that can give anything a charming, rustic appeal. It adds a super cute DIY touch anywhere you hang it. However, if you want your outdoor wooden signs to stand the test of time, you'll have to weatherproof them.

Wood is a natural material that's popular in building and decoration of all types but the truth is, it can be a whole lot of work. The problem is that wood is very susceptible to the ravages of weather.

This material tends to shrink and swell due to temperature fluctuations. Wood shrinks in cold weather and expands in hot weather, which can create cracks.

Moisture can also damage wood, as can rot. In just a short amount of time, the elements will quickly batter unprotected wood and paint until your sign is shabby and your message unreadable.

However, wood is affordable, easy to work with, and available everywhere. You can paint and cut wood to look exactly the way you want it to look, which makes this an ideal material for DIYers.

Working with wood is easy and it's a natural material, something that appeals to environmentalists. Luckily, the inherent problems with wood can be resolved with good waterproofing and regular treatment.

Give your wood the treatment it needs to withstand the weather and your sign stands a much better chance of standing the test of time. This will keep that outdoor waterproof sign looking charming for a long time, rather than giving you weathered wood that’s been weakened by the elements.

How to Make an Outdoor Sign Waterproof

It's easier to start with waterproof outdoor signs made with treated wood than to learn how to make an outdoor sign waterproof but it is actually worth the work to learn this process.

You will work with many kinds of wood if you plan on doing a lot of DIY projects, so it's very useful to know how to weatherproof wood because this is a very common building material.

Decks, outdoor furniture, and many other building and decorative elements you use outside in lawn and garden areas are made with wood. Once you know how to make an outdoor sign waterproof, you know how to make any number of wood objects waterproof and weatherproof so they will look nicer for longer.

hand sanding wood surface

1. Sand the Wood

Start with a nice, smooth surface. Even new wooden signs that are just made might need to be sanded, as will older wooden signs that have been in use.

Use sandpaper to smooth away any rough or rotted areas so you have a nice surface to work with. Moisture and ice will cling to little chips and rough pieces of wood, so this is a necessary step.

2. Clean the Sign

Brush all the sawdust off the sign and clean it thoroughly with a damp cloth to remove any dust and debris that might be sticking to the wood. Don't use paper towels, as this can leave behind lint and that defeats what you're trying to do.

If you see any signs of rot or mildew, apply bleach to the area to kill this ugly stuff. Wash and dry the sign thoroughly before you move on.

3. Fill the Gaps

Use wood putty to fill in scratches, holes, and any damaged or pitted areas you see on the surface of the wood. Apply the putty liberally and allow it to dry.

Once the putty has fully dried, sand it down smooth and clean your wood again.

Repeat this as many times as necessary to fill in holes and gaps and scratches and leave yourself with a clean, smooth piece of wood you can work with. Make sure the putty is totally dry before you proceed to the next step.

4. Apply Primer

Cover the outdoor waterproof sign front, back, and sides with rust-inhibiting primer. You can find this in a spray-on formula or a paint-on formula.

The sign should be covered liberally and allowed to dry thoroughly. This primer will help to prevent moisture damage and add waterproofing power to the sign.

You might need more than one coat of primer before you achieve full coverage. Remember that there is no such thing as too much waterproofing, only too little.

5. Paint It

Now is the time to paint or stain your sign as desired using a polyurethane-based formula. The polyurethane protection adds moisture resistance.

Choose outdoor paint to make sure it will hold up to the water and that it's formulated to resist moisture. Apply as many coats of paint or stain as you like to get the desired look you want and let this dry completely.

The paint or stain color can be at your discretion. The great thing about wood is that it takes different colors very well, so you can truly make it look the way you want it to look.

6. Seal It

Next, cover your sign with polyurethane to seal the wood completely. This will be painted on the same way you would apply stain or paint of any kind.

Work with long, smooth strokes and a clean paintbrush or roller to get good coverage and create a nice seal for the wood. You should let the first coat dry completely and then apply a second coat to get good, thick coverage.

Remember to apply polyurethane on the front, back, and sides of the sign. Polyurethane is a perfect outdoor wood sign sealer.

There are spray-on and paint-on varieties of polyurethane you can use. Choose the material you think you can work with best to decide which to use for your weatherproof signs.

wooden welcome sign

DIY Custom Weatherproof Outdoor Signs

Nothing looks quite as charming as an outdoor weatherproof welcome sign that greets people as they approach your property. Once you know how to make DIY weatherproof outdoor signs, you can add them anywhere and really have fun playing around with this look.

However, these signs will only look nice for a relatively brief period of time unless you take the steps to waterproof them and then treat the sign every one to two years. You will want to apply a new polyurethane coat and possibly a new coat of paint or stain in order to freshen up the sign and keep it resistant to the weather.

Weatherproof Outdoor Wooden Signs FAQs

How do you seal a wooden sign for outdoor use?

Wooden signs can be turned into outdoor weatherproof signs using the same exact methods that homeowners use to waterproof wood. Decks, fences, and other outdoor structures are very commonly sealed with polyurethane and treated with the same products you use for creating weatherproof signs.

All you need to do is prep the wood, paint or stain the wood, and then seal the wood. This is a simplified explanation of how to weatherproof wood, whether you're using the process of weatherproof outdoor signs or some other structural or decorative element outside your home.

What is the best sealer for outdoor wood signs?

When you're wondering how to seal outdoor paint wood sign projects you've worked on, you're going to want to know what the best sealer to use is.

Polyurethane is really perfect for resealing wood and adding a waterproof coating to the material that will protect it from the weather outside your home. You can find polyurethane in many different forms at any home improvement store.

The material is readily available and easy to use and it can be applied to any type of wood to add a strong, waterproofing seal.

What kind of wood should I use for an outdoor sign?

What kind of wood should you use to create your future weatherproof outdoor sign? This is a big question because there are so many different wood options available to you and it's very difficult to know the differences between them all and it can all get very overwhelming.

Look for specific types of wood, rather than specific varieties, to make it easier on yourself. For example, don't seek out specific woods like acacia and oak, look for general hardwoods.

All hardwoods make for strong outdoor signs and other furnishings and decorative elements. Hardwoods to look for include maple, cherry, and some types of teak.

A more affordable option might be medium-density overlay. This is a composite wood using marine-grade plywood and medium-density fiberboard.

Together, these materials create a very tough wood that's perfect for signs and well within many DIY budgets.

Medium-density overlay is usually less expensive than hardwoods. Spend a little time shopping around, however, and you may end up getting a great deal.

How do I weatherproof my outdoor signs?

If you don't weatherproof your outdoor signs, they will end up turning gray and looking rather unattractive. The wood may also develop rotted spots and start to look quite ragged as they're exposed to the outdoors over time.

Weatherproof outdoor signs by painting or staining them to get the appearance you want and then apply a coat of polyurethane to seal out moisture and add the waterproofing weather-fighting power you want to see for your DIY wood projects.

Once you’ve learned how to weatherproof outdoor signs, you know how to weatherproof any type of wood that’s used for anything outside your home.

What is the best material to use for outdoor signs?

When it comes to choosing the best material for outdoor signs, particularly if you want them to be weatherproof and to stand up to time and wear, what's the best one?

There are many materials that make excellent signs. That includes aluminum, which is very lightweight and strong, and naturally resistant to the ravages of the weather.

Vinyl is so durable and so resistant to the weather, it's used for home exteriors. That's definitely a good material to use for outdoor signs, though vinyl doesn't have the natural look that you will get with wood or metal.

If you like the look of wood but you want to work with something much more resistant to water and weather, try dura-wood. This is kind of like a combination of both wood and plastic, so it has more of the look of wood but it has the long-lasting strength of plastic.

Wood is a favorite material to use for outdoor decorative elements because it has a great natural look and it can be painted or stained to any color and finish you want to see.

What is the best type of paint to use for letting on outdoor wooden signs?

Once the wood has been sanded, cleaned, stained, or painted and then treated with a waterproofing sealant, any letters on the sign may not be readable. In any case, you're going to want to brighten up the letters and make sure the wood sign is fully readable.

Unless the letters are engraved or embossed on the surface and already quite easy to see, you’ll need to paint the letters to make them stand out.

To really make the letters on a wooden sign pop, use acrylic paint that's made for outdoor use. This paint is very durable and it comes in a huge range of vibrant colors that take well to wood and stand out beautifully on signage.

Artists often use exterior acrylic paints for murals and outdoor art projects, so you know that this is a good choice for any DIY wooden sign you might want to make. Once you know how to make an outdoor sign waterproof, you can have fun with this DIY project any time.

How do you make a waterproof outdoor sign?

To make an outdoor sign waterproof, start by giving it a good cleaning. Next, cover it with a rust-inhibiting primer that will make it moisture-resistant.

Polyurethane paint will make the sign more waterproof. Once the paint is dry, a coat of polyurethane will add another layer of waterproofing protection.

What kind of wood is best for an outdoor sign?

Sign companies use several different types of wood most often for its durability and natural weather resistance. Waterproof plywood, redwood, and cedar are commonly used by sign makers.

How do you permanently waterproof wood?

Vanish, lacquer, and polyurethane all work well to create a waterproof seal on top of wood to protect it from moisture. However, these coatings need to be re-applied over time.

Nothing makes wood permanently waterproof because even thick finishes will wear away over time.

What is the best sealer for outdoor signs?

Woodworkers have their own opinions when it comes to waterproofing wood. It all really depends on preference, as some swear by varnish and others say lacquer is the best choice.

There are many different types of sealers you can use on wood to add a layer of weather-resistant. Try different ones and you will find your own favorite in time.

Can you paint wood to make it weatherproof?

Paint does seal and protect wood from water and weather but it doesn't last forever. Cracks and chips can appear in the paint, which exposes the wood to the elements.

Further Reading

4 Benefits to Using Exterior Wood Stain

5 Pro Tips for Working With Wood

How to Create a Distressed Wood Finish

Pros and Cons of Polyurethane Finish

Stained and Blemished Wood Repair

Water-Based Polyurethane vs Oil-Based Polyurethane