5 Best Water Sealers for Decks [In 2025]

Keeping your outdoor wooden surfaces, such as decks, fences, and patio furniture, in top condition is essential for maintaining their beauty and longevity. One of the best ways to achieve this is by using a high-quality water sealer. In this comprehensive product review, we’ll explore some of the top water sealers on the market, helping you make an informed decision to protect your valuable outdoor investments.

5 Best Water Sealers for Decks Reviews

Thompson’s Water Seal 21802 VOC Wood Protector, 1.2-Gallon, Clear

Overview

The Thompson’s Water Seal 21802 VOC Wood Protector is a versatile, clear wood sealer that offers a 3-way protection for exterior wood. It penetrates deep into the wood to protect against rot and mildew, providing waterproofing to prevent warping, cracking, and splitting. Additionally, it contains a UV absorber to help retard the fading and drying caused by sunlight exposure.

Specs

• Provides 3-way protection: rot, mildew, and waterproofing
• Penetrates deep into the wood
• Contains UV absorber to prevent fading and drying
• Can be applied over weathered, painted, or stained surfaces
• Paintable and stainable with oil-based products
• Meets VOC requirements in most areas

Pros

• Offers comprehensive protection for exterior wood
• Can be used on a variety of surfaces, including weathered and painted wood
• Helps prevent common wood issues like warping, cracking, and splitting
• Contains UV protection to maintain the appearance of the wood
• Meets VOC requirements, making it environmentally friendly

Cons

• Clear finish may not provide the desired aesthetic for some users
• May require multiple coats for optimal protection
• Some users have reported difficulty with application and uneven coverage

Customer Reviews

The Thompson’s Water Seal 21802 VOC Wood Protector has received generally positive reviews from customers, with an average rating of 4.6 out of 5 stars on Amazon. Users have praised its ability to effectively waterproof and protect their outdoor wood surfaces, with many noting the long-lasting results. However, some customers have mentioned challenges with application and achieving a consistent finish.

Thompson’s WaterSeal Solid Color Waterproofing Wood Stain and Sealer, Natural Cedar, 1 Gallon

Overview

The Thompson’s WaterSeal Solid Color Waterproofing Wood Stain and Sealer is a versatile product that not only seals and protects your outdoor wood surfaces but also adds a rich, solid color finish. The advanced polymers in this stain provide fade-resistant color that maintains its vibrant appearance over time. It’s easy to apply and can be used on both damp and dry wood, making it a convenient choice for a variety of projects.

Specs

• Provides a solid, boldly colored finish that hides the wood grain
• Fade-resistant color formula for long-lasting beauty
• Can be applied to damp or dry wood
• Exceeds the ASTM D-4446 industry standard for waterproofing wood
• Available in a range of color options

Pros

• Adds a rich, solid color finish to outdoor wood surfaces
• Helps protect against water damage and UV exposure
• Fade-resistant formula maintains the color over time
• Can be applied to damp or dry wood for convenience
• Exceeds industry standards for waterproofing performance

Cons

• The solid color finish may not be desirable for all users
• Requires thorough surface preparation for best results
• Some users have reported uneven coverage or difficulty with application

Customer Reviews

The Thompson’s WaterSeal Solid Color Waterproofing Wood Stain and Sealer has received positive reviews from customers, with an average rating of 4.5 out of 5 stars on Amazon. Users have praised the product’s ability to provide a durable, waterproof finish that enhances the appearance of their outdoor wood surfaces. However, some customers have noted challenges with application and achieving a consistent, even coverage.

SEAL-ONCE Marine Ready Mix – 1 Gallon Penetrating Wood Sealer Waterproofer & Stain (Coastal Gray)

Overview

The SEAL-ONCE Marine Ready Mix is a high-performance, water-based wood sealer and stain designed for use in high-moisture areas, such as docks, decks, and piers. Its ultra-low VOC formula penetrates deeply into the wood to provide comprehensive protection against water damage, rot, and UV exposure. This product is ideal for a variety of outdoor wood surfaces, including fences, log homes, and outdoor furniture.

Specs

• Water-based, ultra-low VOC formula
• Penetrates deeply into the wood for enhanced protection
• Suitable for use in high-moisture areas like docks and piers
• Provides waterproofing, UV protection, and resistance to rot and mildew
• Available in a range of color options
• Exceeds industry standards for waterproofing performance

Pros

• Formulated for use in high-moisture, marine environments
• Penetrates deeply into the wood for long-lasting protection
• Offers comprehensive protection against water damage, UV exposure, and rot
• Water-based, low-VOC formula is environmentally friendly
• Available in a variety of color options to suit different preferences
• Exceeds industry standards for waterproofing performance

Cons

• May require multiple coats for optimal coverage and protection
• Some users have reported difficulty with application or uneven results
• The color options may not appeal to all users

Customer Reviews

The SEAL-ONCE Marine Ready Mix has received generally positive reviews from customers, with an average rating of 4.3 out of 5 stars on Amazon. Users have praised the product’s ability to effectively protect their outdoor wood surfaces, particularly in high-moisture areas like docks and piers. However, some customers have noted challenges with application and achieving consistent coverage.

DEFY Extreme Composite Deck Sealer – Crystal Clear Waterproof Sealant for Wood & Composite Surfaces with Zinc Nano-Technology

Overview

The DEFY Extreme Composite Deck Sealer is a crystal-clear, waterproof sealant designed to protect both wood and composite outdoor surfaces. Featuring advanced zinc nano-technology, this sealer helps to shield against water damage and UV exposure, preserving the appearance and integrity of your decks, fences, and other outdoor structures.

Specs

• Crystal-clear formula that won’t change the natural appearance of the wood
• Zinc nano-technology provides enhanced protection against water and UV damage
• Suitable for use on both wood and composite surfaces
• Dries to a transparent, satin-like finish
• Formulated with high-quality materials for long-lasting performance

Pros

• Preserves the natural appearance of wood and composite surfaces
• Provides comprehensive protection against water and UV damage
• Suitable for use on a variety of outdoor surfaces
• Dries to a durable, satin-like finish
• Formulated with high-quality materials for long-lasting results

Cons

• May require multiple coats for optimal coverage and protection
• Some users have reported difficulty with application or uneven results
• Relatively more expensive than some other water sealer options

Customer Reviews

The DEFY Extreme Composite Deck Sealer has received positive reviews from customers, with an average rating of 4.4 out of 5 stars on Amazon. Users have praised the product’s ability to effectively protect their outdoor surfaces while maintaining a natural, transparent appearance. However, some customers have noted challenges with application and achieving consistent coverage.

Thompson’s WaterSeal Solid Color Waterproofing Wood Stain and Sealer, Chestnut Brown, 1 Gallon

Overview

Similar to the Natural Cedar version, the Thompson’s WaterSeal Solid Color Waterproofing Wood Stain and Sealer in Chestnut Brown offers a rich, bold color finish that enhances the appearance of your outdoor wood surfaces. This stain and sealer combo provides comprehensive protection against water damage and UV exposure, ensuring your decks, fences, and other structures maintain their beauty for years to come.

Specs

• Provides a solid, boldly colored finish that hides the wood grain
• Fade-resistant color formula for long-lasting beauty
• Can be applied to damp or dry wood
• Exceeds the ASTM D-4446 industry standard for waterproofing wood
• Available in a range of color options, including Chestnut Brown

Pros

• Adds a rich, solid color finish to outdoor wood surfaces
• Helps protect against water damage and UV exposure
• Fade-resistant formula maintains the color over time
• Can be applied to damp or dry wood for convenience
• Exceeds industry standards for waterproofing performance

Cons

• The solid color finish may not be desirable for all users
• Requires thorough surface preparation for best results
• Some users have reported uneven coverage or difficulty with application

Customer Reviews

The Thompson’s WaterSeal Solid Color Waterproofing Wood Stain and Sealer in Chestnut Brown has received positive reviews from customers, with an average rating of 4.5 out of 5 stars on Amazon. Users have praised the product’s ability to provide a durable, waterproof finish that enhances the appearance of their outdoor wood surfaces. However, some customers have noted challenges with application and achieving a consistent, even coverage.

Buying Guide: Choosing the Best Water Sealer for Your Deck

Type of Surface

• Consider the type of wood or composite material on your deck or outdoor surfaces. Some sealers may be better suited for specific materials, so it’s important to choose a product that is compatible with your surfaces.

Waterproofing and Protection

• Look for sealers that offer comprehensive protection against water damage, rot, mildew, and UV exposure. These features will help extend the life of your outdoor surfaces.

Finish and Appearance

• Decide whether you prefer a clear, natural finish or a solid color stain. The finish can significantly impact the overall appearance of your outdoor spaces.

Application and Ease of Use

• Consider the ease of application, including whether the sealer can be used on damp or dry surfaces, and how many coats are required for optimal coverage.

Environmental Considerations

• If you’re concerned about the environmental impact, look for water-based, low-VOC formulas that are more eco-friendly.

FAQ

How often should I apply a water sealer to my deck?

The frequency of reapplying a water sealer will depend on factors like weather exposure, foot traffic, and the specific product used. Generally, it’s recommended to reapply the sealer every 1-2 years to maintain optimal protection.

Can I use a water sealer on composite decking?

Yes, some water sealers, like the DEFY Extreme Composite Deck Sealer, are specifically formulated for use on both wood and composite outdoor surfaces. Be sure to check the product’s specifications to ensure compatibility with your deck material.

How do I prepare the surface before applying a water sealer?

Proper surface preparation is crucial for the water sealer to adhere effectively. This typically involves thoroughly cleaning the surface, removing any existing stains or sealers, and allowing the wood to fully dry before application.

Can I apply a water sealer over a painted or stained surface?

Yes, some water sealers, like the Thompson’s Water Seal 21802 VOC Wood Protector, can be applied over weathered, painted, or stained surfaces. However, it’s important to follow the manufacturer’s instructions for surface preparation to ensure proper adhesion and performance.

How do I know when it’s time to reapply the water sealer?

Signs that it’s time to reapply the water sealer include fading, peeling, or signs of water damage on the surface. Regularly inspecting your outdoor surfaces and following the manufacturer’s recommended reapplication schedule can help you maintain optimal protection.

Conclusion

Protecting your outdoor wood surfaces with a high-quality water sealer is an essential step in preserving their beauty and longevity. The products reviewed in this guide offer a range of features and benefits, from comprehensive