Wood is a versatile, beautiful material that can add warmth and character to outdoor structures and furniture. However, because it is porous and organic, wood used outdoors needs protection from water damage. Properly waterproofing wood is essential for preserving its structural integrity and aesthetic appeal. With the right products and techniques, you can create water-resistant wooden items optimized for the elements.
Why Waterproofing Wood is Important
Wood that is repeatedly exposed to moisture can develop issues like:
- Warping – Wood swells and shrinks with changes in humidity. Too much water causes uneven shapes and boards bowing up or down. This destroys the original form.
- Rotting – Excess water breaks down wood cells. Rot spreads quickly, causing decay, mold, and structural weaknesses.
- Discoloration – Wet wood enables mold growth, which leaves behind unsightly stains. It can also leach out natural wood pigments.
- Splintering – Water makes wood brittle. The expansion and contraction from moisture changes causes cracks and splintering.
- Weakened Protection – Any previous sealants, stains, etc. will deteriorate faster when subjected to outdoor moisture over time.
Proper waterproofing provides a barrier against liquid water and moisture vapor absorption. This preserves the wood’s cellular structure and prevents the issues above.
Prep Work – Clean and Ready the Wood Surface
Before starting the waterproofing process, prepare the wood using these steps:
- Choose exterior-grade wood, such as cedar, cypress, or treated lumber. Avoid softwoods like pine that easily soak up moisture. Hardwoods have a naturally tighter grain and resist water better.
- Remove any previous coatings with chemical stripping products or sanders. Get down to bare wood.
- Replace any rotted areas, damaged grooves, loose joinery, etc. Use good wood putty products to patch holes and dents.
- Sand the wood thoroughly with increasingly finer grit sandpaper up to 220-grit. This smoothes the surface for better waterproofing adhesion.
- Vacuum and wipe away all wood dust and debris which could mess up finishes.
- Let the wood dry out completely before starting. The moisture content should be below 15%.
- Consider using wood conditioner first for soft, porous woods to limit absorption issues.
Selecting a Waterproofing Method and Products
There are several good waterproofing options and categories to consider:
Oil-Based Wood Sealers
- Tung and Linseed Oils – Absorb into the wood grain for moisture protection from inside. Require frequent reapplication for continuity.
- Polyurethanes – Form protective top layers via evaporation as varnishes and lacquers. Offer durable protection for up to 5 years.
- Penetrating Oils – Oils fortified with waxes and resins get deep into the wood pores for long-term protection. Eco-friendly options available.
Water-Based Sealers
- Water-Repellent Preservatives – Contain waxes, oils, and/or resins to repel water. Work as a primer before varnishing.
- Water-Based Polyurethanes – Acrylic versions of polyurethane that are safe, easy cleanup with water. Good scratch resistance.
- Spar Urethanes – Form flexible, watertight, and UV-resistant film ideal for outdoor use. Require minimal maintenance.
Epoxy Resins
- 100% Epoxy – Used as a flood coat over wood, epoxy resins create a plastic-like waterproof barrier top layer.
- Epoxy Wood Repair Putty – Handy for fixing small damaged areas and gaps vulnerable to water issues. Fills and seals.
Waxes
- Paste and Liquid Waxes – Provide moderate water resistance with a natural look. Need frequent re-coating every 1-2 years.
- Wood Paraffin Wax – Seals wood pores fully when melted into the surface. Repels moisture well and is non-toxic.
No product can guarantee 100% waterproofing forever. Consider moisture exposure levels, aesthetics, topcoat compatibility, and reapplication schedule when choosing wood sealers. Combining methods, like wax over polyurethane, can also optimize water resistance.
Application Tips and Tricks
Follow these best practices during the waterproofing process:
- Check weather forecasts. Avoid applying sealers in excess humidity, rain, frost, or temperatures outside the product’s recommended range.
- Use protective gear like gloves, goggles, and masks to avoid contact irritation. Work in a well-ventilated area.
- Carefully follow all manufacturer’s instructions for application methods, dry time, number of coats, cleanup, etc.
- Apply in the direction of the wood grain with good quality brushes. Maintain a wet edge and avoid foamy brush marks.
- Allow proper drying time between coats. Lightly sand between coats for the best adhesion results.
- Inspect for continuity in coverage after drying. Touch up any thin spots, drips, or misses before adding topcoats.
- Check that any moving parts still function smoothly after waterproofing. Avoid getting sealers in joint areas.
- Allow a full curing time as advised before use. Do a water droplet test to check hydrophobic properties.
With careful prep work, the right product choices, and proper application techniques, you can give your valued wooden structures reliable moisture protection for seasons to come. Maintain the waterproofing integrity with periodic inspection, cleaning, and reapplication as needed.
Frequently Asked Questions
What are the best waterproofing products for wooden decks?
For decks, most experts recommend penetrating oils or marine spar varnish. The oil soaks deep into the wood grain for all-over protection. Spar varnish forms a solid film barrier that handles heavy foot traffic.
Do waterproof wood sealers prevent warping?
Not completely, but they help minimize warping and cracks by limiting how much moisture the wood can absorb. Proper sealing maintains more consistent wood swelling and contraction.
Can I use the same sealers for indoor and outdoor wood?
It’s best to use exterior-grade sealers formulated for outdoor waterproofing on decks, furniture, etc. Indoor wood sealers are meant for low-moisture areas and often lack UV filters.
How long does waterproofing treatment last on wood?
Depending on the product, weather, usage levels, and type of wood, waterproofing can last 1-5 years typically. Oils require more frequent coating, while epoxies and varnishes last longer per application.
What’s the difference between water-resistant and waterproof wood?
Water-resistant wood has protective qualities that reduce water absorption. But it can still become saturated over time. Waterproof wood won’t absorb liquid water when sealed correctly but may absorb some moisture vapor.
Conclusion
Maintaining wood’s integrity against outdoor exposure requires paying special attention to proper waterproofing. Taking time to prepare the surface thoroughly, evaluate sealing options, apply products carefully, and perform regular maintenance will provide long-lasting protection. With the right systems in place, you can fully enjoy the natural beauty of wood in outdoor environments for years before reapplication is needed.