This post was updated on May 8, 2025
Varnish vs Deck Stain: Which Option Provides Better Protection for Your Deck?
Should I use wood stain or varnish to maintain my deck? I don’t recommend using varnish or polyurethane on outdoor decks because they will quickly peel and often fail to prevent sun damage. In many cases, homeowners seeking a shiny, glossy surface will try using varnish outdoors, which becomes a frustrating, ongoing maintenance project.
Key Takeaways
- Varnish is best suited for protecting and enhancing wood that is located indoors.
- Unlike deck stain, which penetrates the wood, varnish protects wood by creating a top coat.
- The harsh outdoor elements, including moisture and ultraviolet rays, will cause varnish to peel and blister and allow mildew development.
Understanding Varnish: More Than Just a Glossy Finish
Varnish is a liquid coating containing oil, resin, and solvent that forms a transparent finish to protect and enhance the appearance of wood surfaces. I often notice that people (mistakenly) use the term “varnish” very generally to describe coatings such as lacquer, shellac, or polyurethane. Varnish is designed to prevent water penetration, limit impact damage, and provide some protection from UV rays.
Deck Stain Demystified: A Natural Look with Solid Protection
Wood deck stains can prevent damage caused by UV rays, moisture, mold, and mildew. Deck stains may be clear, transparent, semi-transparent, semi-solid, or solid and have either a water or oil base.
Choose a high-quality deck stain that is correctly formulated to meet your specific needs based on the condition of the deck and climate. Transparent stains are great for protecting and enhancing the appearance of wood that is in good condition. Semi-solid or solid stains offer coverage that will minimize the imperfections found on older decks.
Key Differences Between Varnish and Deck Stain
When comparing wood stain vs varnish, it is important to understand the primary differences.
- Most deck stains penetrate the wood to create a protective layer, while varnish forms a top layer or coating.
- Deck stain is available in various opacities, while varnish is typically transparent.
- Unlike deck stain, varnish usually dries to a shiny, glossy finish–but formulas now also exist that generate a satin or matte finish.
- While both varnish and deck stain protect wood, most varnishes lack adequate UV protection and begin to flake or peel on exterior decks.
When to Choose Varnish for Your Deck
I discourage using varnish, polyurethane, or urethane coatings on exterior wood decks. Although these options generally work well indoors, they will likely blister or peel when exposed to outdoor elements, including extreme moisture and UV rays.
When to Choose Deck Stain for Your Deck
I recommend applying transparent stains annually and semi-transparent, semi-solid, and solid stains every two to three years. The surface preparation process, which may include cleaning, stripping, brightening, and drying, is critical before staining. Always allow the stain time to penetrate the wood and remove any remaining excess.
When choosing a stain, select one that is appropriate for the deck’s condition and the local climate. Check out my post regarding when to initially stain new wood decks.
Cost Considerations: Varnish vs Deck Stain
What is the difference between stain and varnish from a cost perspective? Most of my favorite wood deck stain brands, including Restore-A-Deck, TWP, and Armstrong-Clark, sell for between $45 and $79 a gallon.
I don’t suggest using varnish or shiny type coating as an alternative to wood deck stain.
Take the Next Step: Find the Perfect Finish for Your Deck
Finding the best deck stain for your specific needs is critical. Consider thesetips:
Transparent parent stains are ideal for newer decks to enhance the wood’s natural appearance.
With more “paint-like” properties, semi-solid or solid stains provide the coverage needed to conceal flaws and imperfections on older decks.
Choose stains with powerful UV protection for decks exposed to direct sunlight and those containing mildewcides and algaecides to stopmold and mildew in damp, humid climates.
Semi-transparent stains offer agood balance of benefits.
Water-based stains are generally more eco-friendly and easier to clean up compared to oil-based options.
Oil-based stains typically offer better penetration and protection, but usually come in fewer colors, are more expensive, and have restricted availability based on your state’s VOC regulations.
FAQs: Varnish vs Deck Stain
Can I mix varnish and deck stain on the same deck?
No. I don’t recommend mixing varnish and stain, as it will negatively alter the stain and void the manufacturer’s warranty.
Is there a clear winner between varnish and deck stain for durability?
To broadly compare the durability of varnish vs stain is rather indeterminate. Although both varnish and stain protect wood, there are many types of each, most of which are specially formulated. On exterior wood decks, varnish typically struggles to withstand the elements and is more susceptible to fading, peeling, and blistering than stain. For maintaining your deck, I recommend choosing a deeply penetrating deck stain.
How do I know if my deck needs to be stripped before applying a new finish?
It is important to always completely remove any remnants of the existing stain before staining your deck. Deck stain strippers soften existing coatings for easier removal and clear the surfaces of mold, mildew, or dirt. Strippers are most effective with removing clear, transparent, or semi-transparent stains, not paints, solid stains, or varnish.
Does varnish make wood waterproof?
No. While it will create a protective coating, it doesn’t 100% waterproof the wood.
Does varnish protect wood from rotting?
Wood decay, commonly referred to as “wood rot”, is a process of decomposition or disintegration caused by fungal growth. Varnish will not form a barrier that prevents moisture intrusion, stopping fungal development.
How often do I need to reapply deck stain compared to varnish?
A good-quality, semi-transparent, semi-solid, or solid deck stain should last two to three years on horizontal surfaces and at least four years on vertical surfaces. Clear or transparent deck stains are less durable and often must be reapplied each year. I’ve found that varnishes will soon begin to peel when faced with outdoor elements and require frequent reapplication.
