The best thing you can do to the lifespan of your outdoor wood furniture and decking and fences is to apply a waterproof stain. Unsealed wood can soak up water and will eventually warp, crack or even rot from mold and mildew. So you might be thinking: How do I waterproof wood quite easily since this natural material isn’t always so low-maintenance?
This guide has 6 ways to do it — and mistakes and tricks to help keep it looking good for others down the line.
Why Waterproofing Wood Matters
- Moisture Protection: It does not inflate with water, deforming or roting.
- UV Resistance: Wood finish protects against the damage from sun.
- Longevity: They make furniture, decks and fences last for decades.
- Aesthetic Appeal: Keeps and/or enhances appearance of wood with stains.
6 Methods to Waterproof Wood (and How to Apply Them)
1. Epoxy Sealer + Exterior Varnish (Most Durable)
How to Apply:
- Sand the wood surface smooth and wipe it clean of any dust.
- Apply an thin, even layer of epoxy sealer using a brush or foam roller.
- Let it cure thoroughly (check for the manufacturer’s instructions).
- Sand lightly with fine-grit sandpaper.
- Apply 2-3 coats of marine varnish or spar varnish and sand in between.
- Allow the final coat to cure for 2-3 days before using.
Best For: Outdoor furniture, boats and any wood subjected to harsh weather conditions.
2. Synthetic Sealants (Varnish, Polyurethane, Lacquer)
How to Apply:
- Sand the wood lightly and wipe off dust.
- Stir (don’t shake) the sealant to avoid the bubbles.
- Use a synthetic brush and it is best to follow with the wood grain.
- Let dry: 2 hours for water-based, 4+ hours for oil-based.
- Sand lightly between the coats.
- For added strength, apply 2-3 coatings.
Best For: Indoor furniture, cabinets, and moderate outdoor use.
3. Natural Oils (Tung Oil, Linseed Oil, Danish Oil)
How to Apply:
- Stir the oil gently.
- Apply with a lint-free cloth or brush, moving along the grain.
- Wipe away any excess oil to prevent the sticky spots.
- Allow to soak for 30–60 minutes, then buff with a clean cloth.
- Apply 2–4 coats, letting each dry for 24 hours.
- To maintain it solid, you simply need to reapply every 6-12 months!
Best For: Butcher blocks, countertops, cutting boards, or homeowners who prefer a natural finish.
4. Stain + Sealer Combinations
How to Apply:
- Clean and sand the wood until it’s smooth.
- Stir the stain well (never shake).
- Apply by brush, roller, pad or sprayer and keep a “wet edge.”
- Drying time: 1-2 hours (water-based), 2-4 hours (oil based).
- Apply a second, one if you need.
- Just leave it and wait 2–3 days before laying down furniture or placing anything heavy on top of it.
Best For: Decks, fences, railings, and siding.
5. Wood Sealers (Clear or Tinted)
How to Apply:
- Make sure that the wood is perfectly dry (moisture under 12%).
- Sand the surface and wipe it clean.
- Apply sealer with a paint-brush, applicator pad or sprayer.
- And it’s all about a fine, even application — no streaks allowed.
- Allow to dry thoroughly, then apply a second coat.
- Add a new coat every 3-5 years, or as necessary.
Best For: Furniture, flooring, and wood where you want a “barely there” look.
6. Paint or Primer-Sealer Systems
How to Apply:
- Sand the wood and remove dust.
- Apply a primer-sealer to lock in the wood’s surface.
- Allow primer to dry fully.
- Apply 2 coats of exterior paint rated for waterproofing.
- Let each coat dry as instructed (usually 4-6 hours).
- Put on a coat of clear exterior polyurethane for additional hardiness.
Best For: Sheds, fences, siding, and older wood surfaces.
Also read:
Lacquer or Polyurethane ? – Which is best for me
Common Mistakes to Avoid When Waterproofing Wood
Skipping Surface Preparation
The reason is that dirt, dust and old coatings prevent good adhesion. Before closing it, you should first clean and sand the piece.
Applying to Damp Wood
Traps moisture inside, leading to rot. Make sure that the Humidity is under 12%.
Not Using Enough Coats
A single coat simply will not suffice — in the case of most, 2–3 coats are how you get great coverage.
Forgetting UV Protection
Sealers alone might prevent water, but they won’t stop damage from sun. Never use anything other than UV resistant finishes on woodwork outside.
Infrequent Maintenance
Best case scenario, even the best waterproofing needs to be reapplied. You have to inspect yearly and reseal when water no longer beads.
Using Indoor Sealers Outdoors
The Products which are not designed for outside use will quickly deteriorate in either rain or sun.
Expert Tips for Long-Lasting Waterproof Wood
Perform the water-drop test: Sprinkle water on the wood— and if it soaks in, then it’s time to reseal it.
Choose the right finish: Try to use the solid stains for the older & weathered wood; transparent/semi-transparent for new, high-quality wood.
Elevate outdoor furniture: Keep off the floor to prevent absorption of moisture.
Cover when not in use: Long lasting cover, is an extra layer of protection when your outdoor furniture is not being used.
Sand lightly between coats: Creates a stronger bond for finishes.
FAQs About Waterproofing Wood
1. What is the best method to waterproof outdoor wood?
The most durable method is epoxy sealer plus exterior varnish, especially for the furniture and decks which are exposed to heavy rain or sun.
2. Can I waterproof wood naturally?
Yes, a natural oil finish like tung or linseed will at least offer water resistance while keeping the wood’s natural look. They need regular reapplication.
3. How often should I waterproof wood?
Most wood surfaces need reapplication every 1–3 years, but natural oils may need touch-ups every 6–12 months.
4. Can I paint over sealed wood?
Yes, but only if the sealer is compatible with paint. Some require sanding before painting for proper adhesion.
5. How do I know if wood needs resealing?
Perform the water drop test: if a water beads up, your seal is still good; if it absorbs, reseal immediately.
6. Is polyurethane waterproof?
Polyurethane is water-resistant but it is not fully waterproof. For maximum outdoor protection, combine it with an exterior varnish or use an epoxy undercoat.
Final Thoughts
Protecting wood involves more than just protection — it also means maintaining its beauty and extending the life of your lumber. The method you choose will depend on what’s most important to you in a finish: epoxy and varnish for maximum strength, natural oils for warmth and tradition, or an oil-based wiping stain/finish combination to get the best of both worlds (what I call beauty with backbone).
