Sealing your deck with Thompson’s WaterSeal is an easy and effective way to protect and preserve the wood. Proper sealing can extend your deck’s lifespan by preventing rot, mold, mildew, and wood damage caused by water, sun exposure, and other elements. This comprehensive guide will provide you with step-by-step instructions for using Thompson’s WaterSeal to seal your deck properly.
Planning Your Deck Sealing Project
Before sealing your deck, take some time to plan your project thoroughly. Proper planning and preparation will ensure the sealing process goes smoothly and maximizes the protective benefits of the Thompson’s WaterSeal.
Choose the Right Time of Year
It’s best to seal your deck during dry weather when no rain is in the forecast for 2-3 days. Spring and fall are ideal times with moderate temperatures. Avoid sealing in direct sunlight or if temperatures exceed 90°F, as the sealant may not penetrate properly. The wood surface must be completely dry before sealing.
Gather the Right Supplies
You’ll need the following supplies:
- Thompson’s WaterSeal product (oil-based or water-based formula)
- Paintbrush(es) – opt for high-quality bristle brushes
- Paint roller and extension pole
- Paint tray with liner
- Drop cloths or plastic sheeting
- Masking tape and painters tape
- Stain remover and deck cleaner (optional)
- Sandpaper (80-100 grit)
- Scraper for removing old sealant
- Safety gear – gloves, goggles, face mask
Choose Your Thompson’s WaterSeal Product
Thompson’s offers both oil-based and water-based WaterSeal formulas. The traditional oil-based version provides excellent penetration and protection. The water-based version has low odor and dries more quickly. Choose the one that best suits your needs.
Calculate How Much You Need
Measure the square footage of your deck using length x width. Consult the Thompson’s product label for coverage rate per gallon. Purchase enough sealant to cover your deck evenly in 2 coats. It’s better to have extra than run out halfway.
Protect Surrounding Areas
Use masking tape, painters tape, and drop cloths to completely cover any surfaces bordering the deck, such as siding, windows, doors, outdoor furniture, etc. This protects from accidental drips or spills.
Clean and Prepare the Deck
Your deck must be thoroughly cleaned and prepped for the sealant to properly adhere. Sweep away dirt and debris with a broom. Use a deck cleaner and rinse thoroughly. Lightly sand to smooth away old stain or glossy areas. Make any necessary repairs before sealing.
Applying Thompson’s WaterSeal
Once you’ve completed the proper prep work, you’re ready to start sealing your deck. This 5-step process will ensure you apply Thompson’s WaterSeal correctly for maximum protection:
1. Read All Label Instructions
Before getting started, read the usage instructions on the Thompson’s WaterSeal container thoroughly. Follow all safety precautions listed on the label. Wear gloves, goggles, and a mask to avoid inhalation. Stir the product well before and periodically during use.
2. Apply First Coat
Use a paintbrush to apply a generous first coat around the edges, in corners, and hard to reach spots. Then use a paint roller to quickly cover the rest of the deck’s surface with an even coat. Apply in the direction of the wood grain.
3. Let First Coat Dry
Allow the first coat to dry completely for at least 24-48 hours before applying the second coat, depending on humidity levels. The deck should look dry and feel firm – not tacky. Proper drying between coats is critical.
4. Apply Second Coat
Once the first coat is fully dry, apply the second coat in the same manner with a paintbrush and roller. Apply generously to ensure even coverage. Two full coats provides maximum protection.
5. Allow Final Cure
After the second coat has dried thoroughly, allow up to 2 weeks for the Thompson’s WaterSeal to fully cure before heavy use of the deck. Avoid parking vehicles on the sealed deck during this time.
Tips for Proper Application
- Always maintain a wet edge when rolling to prevent lap marks.
- Watch for drips and uneven coverage and smooth them out quickly.
- Thoroughly coat end grains, joints, and undersides for full protection.
- Only apply when between 40-90°F and avoid rain for 48 hours.
- Stir sealant occasionally to maintain consistency.
- Allow extra drying time in humid climates.
Using Water-Based vs. Oil-Based Formulas
Thompson’s offers both oil-based and water-based WaterSeal products. Each has advantages:
Oil-Based Advantages
- Provides superior penetration into wood
- Long-lasting protection up to 5 years
- Resists mildew growth on surface
- Ideal for heavily used decks
Water-Based Advantages
- Fast dry time of 1-2 hours per coat
- Low odor and VOC emissions
- Easier soap and water cleanup
- Better for indoor projects
The oil-based version is preferred for most outdoor deck projects, but the water-based version works well too. Test a small hidden area first if unsure.
Sealing Different Types of Deck Wood
Thompson’s WaterSeal is formulated to work on all standard decking woods:
Cedar and Redwood Decks
Allow new cedar and redwood to weather 2-3 months before sealing. These woods contain natural oils that can prevent proper sealant adhesion when new. Weathering allows the wood to properly dry out.
Pressure-Treated Decks
Let new pressure-treated wood dry out for at least 6 months before sealing. The chemicals used to treat the wood initially can also interfere with proper sealant penetration.
Exotic Hardwoods
Ipe, tigerwood, and other dense exotic woods require extra prep before sealing. Sand the surface thoroughly with 60-80 grit sandpaper to ensure the sealant can properly adhere and absorb. Two coats are recommended.
Composite and PVC Decks
Thompson’s WaterSeal is not recommended for composite or PVC decking, as the materials are fabricated to be maintenance-free. Verify your decking type before sealing.
Cleaning and Maintaining a Sealed Deck
Proper care and maintenance will keep your sealed deck looking great. Follow these tips:
- Allow the WaterSeal to cure for 2 weeks before mopping or heavy cleaning.
- Use a mild cleaner like Murphy’s Oil Soap as needed to remove dirt. Avoid harsh chemicals.
- Rinse debris and spills promptly to avoid stains.
- Reapply fresh sealant every 1-3 years depending on usage and exposure.
- Watch for cracks, splinters, or other defects and repair quickly.
- Consider re-sanding and re-sealing if the deck surface becomes very worn.
Avoid using abrasive tools or pressure washing too forcefully when cleaning a sealed deck. This can damage the protective sealant layer over time.
Troubleshooting Common Thompson’s WaterSeal Problems
Sealing a deck with Thompson’s WaterSeal is usually straightforward. But if issues arise, here are some troubleshooting tips:
Problem: Sealant not absorbing into wood.
Solution: Make sure wood is properly cleaned and dried first. Test absorption on a scrap piece before applying.
Problem: Bubbling or peeling of sealant.
Solution: This occurs when coating over damp wood. Allow proper dry time between coats.
Problem: White hazy residue on deck.
Solution: Wait longer between coats to allow proper drying. Or apply in direct sunlight when too cold.
Problem: Lap marks or uneven appearance.
Solution: Maintain a wet edge when rolling. Work in sections and gently smooth drips.
Problem: Mold or mildew growth after sealing.
Solution: Re-clean deck and apply a mildew-resistant sealant like Zinsser per instructions.
If problems persist, completely strip the deck and start the sealing process over from the beginning. Be sure to follow all label directions closely.
Frequently Asked Questions About Thompson’s WaterSeal
Here are answers to some of the most common questions about using Thompson’s WaterSeal deck sealant:
Does Thompson’s WaterSeal expire?
Unopened cans have a shelf life of approximately 5 years when stored properly. Once opened, the remainder should be used up in one season. The sealant may not adhere as effectively if allowed to sit through freezing weather cycles.
What is the best way to apply Thompson’s WaterSeal?
Use a combination of paintbrush and roller. Brush corners and edges first, then quickly roll over the main surface. Maintain a wet edge and work in sections for an even appearance.
How long does Thompson’s WaterSeal take to dry?
In average 70°F temperatures, the first coat dries in 2-3 hours and the second coat in 1-2 hours. Allow 24-48 hours between coats. Low humidity speeds drying. High humidity or cool temps can double drying times.
Does Thompson’s WaterSeal leave a finish or sheen?
No, Thompson’s WaterSeal penetrates into the wood grain without leaving any glossy film or sheen on the surface when dry. It allows the natural look of the wood to show through.
How often should Thompson’s WaterSeal be reapplied?
On decks with average usage, reapply every 2-3 years. Heavily used or sun-exposed decks may need re-coating annually. When water absorption decreases and the wood looks faded, it’s time to re-seal.
Can I use Thompson’s WaterSeal on damp wood?
No, only apply to thoroughly dry wood. Any residual moisture trapped under the sealant can cause major adhesion issues like peeling and bubbling. Always allow 2-3 sunny days for proper drying first.
Is one coat of Thompson’s WaterSeal enough?
Two full coats are highly recommended for sufficient protection, especially on horizontal exterior deck surfaces. The second coat fills any gaps missed initially. One coat only provides minimal protection.
How should I prepare pressure-treated wood before using Thompson’s WaterSeal?
Allow new pressure-treated wood to dry out completely for at least 6 months before sealing. This allows any chemicals from the pressure-treating process to dissipate so they don’t interfere with proper sealant bonding and absorption.
Safety Precautions When Working With Thompson’s WaterSeal
Take the following standard safety precautions whenever using Thompson’s WaterSeal:
- Work in a well-ventilated area and wear an appropriate mask or respirator.
- Wear protective gloves, goggles, and clothing to prevent skin and eye exposures.
- Keep away from open flames. Sealant is flammable until fully cured.
- Wash hands, clothes, and brushes thoroughly after use.
- Keep out of reach of children and pets.
- Dispose of used rags properly due to combustion hazard.
- Use a plastic liner in paint tray to simplify cleanup.
- Follow all additional safety tips listed on the Thompson’s WaterSeal label.
Take care when working with any chemical sealant and follow directions to ensure safety. Consult a doctor immediately if rash, nausea, headache or other symptoms occur.
Tips for Achieving Professional Deck Sealing Results
Follow these pro tips to get your deck looking like it was professionally sealed:
- Invest in high-quality application brushes for smoother results.
- Use an extension pole and 18-inch roller to easily cover large areas fast.
- Apply in direct sunlight to prevent lap marks but avoid hot temps.
- Carefully cut-in all edges and details with a trim brush.
- Periodically reshake the bucket to maintain proper mixing.
- Use painters tape and plastic sheeting to completely protect adjacent surfaces.
- Maintain a wet edge and work systematically from one end to the other.
- Apply sealant in a smooth, thin coat without overworking the material.
- Be extremely patient with dry times between coats. Rushing causes adhesion issues.
- Check forecast and allow 3 rain-free days for full drying and cure time.
- Have 2 people coordinate sealing for very large decks.
Patience and proper process are the keys to getting pro-quality longevity from Thompson’s WaterSeal on your deck. Take your time and follow all directions carefully.
The Benefits of Sealing Your Deck Properly with Thompson’s WaterSeal
Investing some time upfront to properly clean, prep, and seal your deck using Thompson’s WaterSeal provides major long-term benefits:
Preserves the Wood Itself
The sealant penetrates deep into the wood grain to protect it from inside and out. This prevents moisture damage, rot, splits, and warping.
Prevents Mold, Mildew, and Algae
Water sealants block moisture that would otherwise feed fungus and algae growth on bare wood. This keeps your deck cleaner.
Reduces Warping, Cupping, and Splintering
Controlling wood’s exposure to moisture minimizes natural expansion, contraction, cupping, and splintering over time.
Maintains a Like-New Appearance
Sealed wood maintains its natural color better rather than turning gray from sun exposure and elements.
Extends Time Between Maintenance
Re-staining or re-sealing becomes necessary less often when wood is properly sealed. Maximizes your investment.
Improves Safety Underfoot
Sealed decks are less slippery than bare wood when damp. The coating provides added traction.
Take the time to properly seal your wood deck at least every 2-3 years to get the most out of your investment while keeping it looking beautiful. Thompson’s WaterSeal is an easy and effective option.
Conclusion
Sealing your wood deck annually or biennially with a high-quality sealer like Thompson’s WaterSeal is the best way to protect your investment and keep the deck looking pristine for decades. Follow the preparation, application, maintenance, and safety tips provided above to get the most from your Thompson’s WaterSeal deck sealer. Patience and proper process are key when applying. Plan your project carefully and don’t cut corners. Your deck will look professionally sealed and provide years of service when you take the time to do it right. Thompson’s WaterSeal makes it easy to seal your deck like a pro.