You’re researching deck protection and wondering how a penetrating sealant compares to Thompson’s Water Seal. It’s a fair question—and we’re going to give you an honest answer, even though we’re one of the options being compared.
Here’s the truth: Thompson’s Water Seal is a solid product for the right situation. But when you’re hiring a professional to apply it—which most homeowners eventually do—the economics change dramatically. Understanding those differences will help you make the right choice for your deck, your budget, and your lifestyle.
How Long Does Thompson’s Water Seal Last?
Thompson’s Original Water Seal typically lasts 1-2 years before reapplication is needed. Their premium products—like WaterSeal MAX—claim 3-5 years, but real-world performance depends heavily on conditions. High foot traffic, direct sun exposure, and coastal or freeze-thaw climates can cut that lifespan significantly. Most homeowners we talk to report resealing every 2-3 years to maintain protection. That’s fine if you’re doing it yourself, but if you’re paying a pro each time, those costs add up fast.
Quick Comparison: Professional Application
| Factor | Thompson’s (Pro Applied) | DuraSeal |
| Protection Duration | 2-3 years | Permanent |
| Cost per Cycle (400 sqft) | $800-1,400 | $1,400-2,400 |
| 25-Year Total (3-year cycle) | $6,400-11,200 | $1,400-2,400 |
| 25-Year Total (2-year cycle) | $9,600-16,800 | $1,400-2,400 |
| Warranty | Product only (no labor) | 25-year transferable |
| Technology | Film-forming (sits on surface) | Penetrating (bonds within wood) |
Understanding the Products
What Is Thompson’s Water Seal?
Thompson’s Water Seal is America’s best-known deck waterproofing product. It’s been around since 1920 and is available at virtually every hardware store. The product line includes several formulations:
- Original Clear: Basic waterproofing, 1-2 year protection
- Advanced Natural Wood Protector: Enhanced waterproofing, 2-3 year protection
- Signature Series Stain + Sealer: Color + protection, 2-4 year protection
- WaterSeal MAX: Their premium line, claims 3-5 year protection
Thompson’s products are film-forming sealers—they create a protective layer on top of the wood surface. This approach provides good short-term waterproofing but requires regular reapplication as the film breaks down from UV exposure, foot traffic, and weather.
What Is DuraSeal?
DuraSeal is a professional-grade penetrating sealer that bonds within the wood fibers rather than sitting on top. This technology permanently protects from the inside out, which is why we offer a 25-year transferable warranty.
DuraSeal isn’t sold in stores—it requires professional application by trained technicians. This isn’t a limitation; it’s by design. The product and application process are engineered together to deliver long-term results that film-forming products can’t match.
The Real Comparison: Professional Thompson’s vs DuraSeal
Most homeowners don’t want to spend their weekends sealing decks. And even those who start with DIY often hire a pro after the second or third application. So let’s compare apples to apples: what does it cost to have professionals maintain your deck with Thompson’s vs. a one-time DuraSeal application?
Professional Deck Sealing Costs
According to Homewyse and industry data, professional deck sealing/staining costs:
- Basic sealing: $1.00-$1.50 per square foot
- Standard stain/seal: $2.00-$3.50 per square foot
- Full service (with prep): $3.00-$6.00 per square foot
- Get your DuraSeal InstQuote here
Note: Rates vary by region and deck condition. Coastal and high cost-of-living areas trend higher.
25-Year Cost Comparison (3-Year Reapplication Cycle)
For a typical 400 square foot deck, assuming you reapply every 3 years (8 applications over 25 years):
| Service Level | Per Application | 25-Year Total | vs. DuraSeal |
| Basic sealing ($1-1.50/sq ft) | $400-600 | $3,200-4,800 | 2-3× more |
| Standard service ($2-3.50/sq ft) | $800-1,400 | $6,400-11,200 | 4-7× more |
| Full service w/ prep ($3-6/sq ft) | $1,200-2,400 | $9,600-19,200 | 6-12× more |
| DuraSeal (one-time) | $1,400-2,400 | $1,400-2,400 | — |
What If It Needs Reapplication Every 2 Years?
Three years is the optimistic scenario. In high-traffic areas, harsh sun, or coastal conditions, many homeowners find themselves resealing every 2 years. That’s 12 applications over 25 years instead of 8—a 50% increase in total cost.
| Service Level | 3-Year Cycle (8 apps) | 2-Year Cycle (12 apps) | Increase |
| Standard service | $6,400-11,200 | $9,600-16,800 | +50% |
| Full service | $9,600-19,200 | $14,400-28,800 | +50% |
| DuraSeal | $1,400-2,400 | $1,400-2,400 | None |
The Inflation Factor
Here’s what these projections don’t account for: inflation. The cost of labor and materials today will be less than the cost in 5, 10, or 15 years. At just 3% annual inflation:
- A $1,000 application today costs ~$1,344 in 10 years
- That same application costs ~$1,806 in 20 years
When you factor in inflation across 8-12 applications over 25 years, your true cost for repeated Thompson’s applications could be 30-50% higher than the baseline projections above.
DuraSeal locks in today’s price for 25 years of protection.
Why Professional Thompson’s Application Costs So Much
Painting companies and handyman services charge by the job, not by how long the product lasts. Every application involves:
- Mobilization: Scheduling, travel, setup, cleanup
- Preparation: Power washing, drying time, light sanding
- Materials: Sealer product, brushes, tape, tarps
- Labor: Typically 4-8 hours for a 400 sq ft deck
- Business overhead: Insurance, licensing, profit margin
You’re paying for that entire process every 2-3 years. And remember: Thompson’s warranty covers the product only—not the labor. If it fails early, you’re paying for another application out of pocket.
What About DIY Thompson’s?
If you’re committed to doing it yourself every 2-3 years, Thompson’s can be cost-effective:
- Product cost: $80-150 per application
- Applications needed: 8-12 over 25 years
- Total materials: $640-1,800
- Your time: 8-12 hours × 8-12 applications = 64-144 hours
DIY Thompson’s is the lowest-cost option—if you value your weekends at zero. But most homeowners eventually decide their time is worth something. And once you hire a pro, the math flips completely in DuraSeal’s favor.
When Thompson’s Makes Sense
We’ll be honest: Thompson’s is the right choice for some situations. Consider Thompson’s if:
- You genuinely enjoy DIY projects and consider deck maintenance a satisfying weekend activity
- You’re selling your home soon and just need the deck to look good for a couple of years
- You need a solution today (professional sealing requires scheduling)
Important: If you’re planning to hire someone to apply Thompson’s, stop and do the math first. Professional application of film-forming sealers rarely makes financial sense over time.
When DuraSeal Makes Sense
DuraSeal is the better investment when:
- You want to solve deck maintenance permanently—one and done
- You were going to hire a pro anyway—DuraSeal costs less than repeated professional Thompson’s applications
- Your time is valuable and you’d rather spend weekends doing literally anything else
- You want to lock in today’s price instead of paying inflated costs for the next 25 years
- You plan to stay in your home long-term (or want the warranty to transfer to buyers)
- You’ve tried DIY sealers and got tired of reapplying
- You have a premium deck (cedar, ipe, redwood) that deserves premium protection
- You want a warranty that actually means something—25 years, transferable, includes labor
Frequently Asked Questions
Can I apply DuraSeal over Thompson’s Water Seal?
Not directly. Thompson’s creates a film that must be removed before penetrating sealers can bond with the wood. If you’ve previously applied Thompson’s, our estimators will assess whether stripping is needed as part of your free estimate.
Is Thompson’s Water Seal bad?
No—it’s a legitimate product that does what it claims. It’s designed for affordable short-term protection, and it delivers that. The problem isn’t Thompson’s itself—it’s the assumption that hiring a pro to apply it repeatedly makes financial sense. It doesn’t.
Why can’t I buy DuraSeal at Home Depot?
Professional penetrating sealers require specific application techniques, surface preparation, and environmental conditions to work properly. Selling the product without the expertise would lead to poor results and frustrated customers. The product and professional application are a package deal.
How long does Thompson’s Water Seal actually last?
In our experience (and based on customer reports), Thompson’s Original lasts 1-2 years in most conditions. Their premium products can last 2-4 years. Harsh sun exposure, heavy foot traffic, and freeze-thaw cycles shorten lifespan significantly. Plan for 2-3 years as a realistic average.
Where do the professional application costs come from?
The professional application costs cited in this article come from Homewyse.com (2026 data), HomeAdvisor, and industry averages. Actual costs vary by location, deck condition, and contractor. We recommend getting multiple quotes for any professional service.
Have additional questions? Read our FAQs.
Ready to Compare for Yourself?
If you’re curious whether DuraSeal makes sense for your deck, we offer free, no-obligation estimates. We’ll assess your deck’s condition, explain exactly what’s involved, and give you a written quote. No pressure—if Thompson’s is the right choice for your situation, we’ll tell you.
Call 888-660-0260 or schedule your free estimate online
