Fully clean the wood with biocidal cleaner and apply an undercoat wood preservative to protect against woodworm and rot. If you'd like to give your outdoor wood a new look, stain the wood to a vivid colour or subtle tint. Finishes seal the wood from moisture, rain and (with some finishes) UV radiation.
There are a few main ways to treat wood for outdoor use. You can use a wood sealer, varnish, or an oil finish. While there are a couple other methods, these aren't an option for the everyday person like me or you. I recommend using a varnish for most projects.
You may need to treat your exterior wood as often as every 6 months, depending on your geographical situation and the type of wood you are treating. But on average, you should treat your outdoor wood every 12-18 months. So, it should be an annual job!
Use a Sealer
One of the most important steps you can take to protect outdoor wood furniture is to use a sealer. A sealer is a transparent finish that is applied to wood to protect it from moisture. Sealers work by penetrating the wood's pores and preventing water from entering.
Tips for Preventing Wood Rot
Always use decay-resistant or pressure-treated lumber for decks. Wood that touches the ground should be pressure-treated lumber that's rated for ground contact. When building an exterior project with wood, stain or paint all sides of each lumber piece before assembly.
Other than rot or physical damage, boiled linseed oil is a great treatment for old dried out wood. It also makes a fantastic pre-treatment before painting to extend the life of your paint job.
Boric acid (borate) is one of the most effective fungicides for use in treating wood rot. It can be applied to wood during construction to prevent future rot, or as a treatment to stop an active decay fungus from growing.
Both water- and oil-based varnishes are designed to penetrate the wood fibers and produce more earthy tones. Another solution for preserving reclaimed wood are waxes. Traditional waxes have an amber tint that's great for new wood but causes reclaimed wood to lose its desirable gray patina.
Some say that untreated 2×4's can last up to two years before showing signs of rot and others say it can last even longer. When deciding if you should you use an untreated 2×4 it depends greatly on the application, how much weather and sun it's exposed to and if it's making ground contact.
There are three types of clear topcoats used to seal natural wood or bleached furniture – polyurethane, polycrylic, and wax finishes.
When it comes to comparing treated wood vs. cedar, pressure-treated wood is the sturdier and more weather-proof of the two. It's highly resistant to insect attack and rot, and special versions rated for “ground contact” can be buried in soil and will continue to shrug off decay for decades.
Storing dry lumber outdoors should be avoided at all costs. The outside elements include water and drastic changes in temperature.
Even loose lumber not treated in any way will be fine; provided it has an opportunity to dry out before covering with drywall. To minimize and eliminate any potential damage to the material, it is important to remove any standing water on the sub floor. This will help the water to dissipate quicker.
Normal rainwater will not harm the wood that is used to build homes. Many homeowners fear that wood will immediately rot if allowed to get wet. That's simply not the case.
Clear Topcoat Sealer can also be used as a durable coating over natural patina in aged, weathered, and repurposed woods.
Linseed oil is a traditional choice for nourishing and protecting wood. It comes in many forms and is obtained from the seed of the linseed-flax plant. Given its ease of use and cheap price, it is one of the most popular finishing oils in the world.
White vinegar will stop wood rot
Because it is a fungicide, which has antimicrobial properties. As wood rot is caused by fungi that require an acidic environment ranging from 0-5.5 (pH), white vinegar solves the problem by changing the pH level in the wood.
The treatment options
As a rule of thumb, wood protectors – often used on pre-treated timbers - protect against the elements, whilst wood preservers protect timber from wood boring insect attack and fungal decay, including 'blue stain'.
Fungicides to defeat brown rot include: baking soda, hydrogen peroxide, tea tree oil, boron solutions, ethylene glycol or propylene glycol, vinegar, etc. Since the dry rot fungus requires an acidic environment from pH 0 to 5.5, certain of these fungicides work because they change the pH.
With this in mind, believe it or not, a bit of canola oil and vinegar makes a brilliant wood sealant, protecting wood from burrowing insects, wear and water. As well as this, this can be reapplied to revitalize the wood, something that won't work without sanding off varnish.
All exterior wood surfaces should be coated with a long lasting, water repellent finish system. This is especially important on log homes. Water-based, breathable film-formers like LIFELINE stains and topcoats work best since they allow water vapor to escape while preventing liquid water from penetrating into the wood.
Solvent-based wood preservers such as Barrettine Premier and Ronseal Total tend to absorb more deeply into wood, and decorators say they have longer-lasting effects. However they're more smelly than water-based stuff, and tend to be less safe for the environment.