Homeowners build timber decks in their yards to use for entertaining and relaxing. Some wood decks have a table where family and friends can eat outdoors in nice weather. Others have a chaise lounge or  two, a hammock or maybe even a few Adirondack chairs where they can curl up with a good book, watch the stars at night or supervise the kids at play. Whatever the purpose of a deck, many homeowners enjoy their outdoor living space.

Over time and exposure to varying weather conditions a wood deck can develop timber rot if it was not properly sealed. If you have a deck that has Trex or other similar composite materials, the upright supports and joists under the Trex are prone to wood rot. While Trex may provide a virtually maintenance free surface, it is not the only material used to build the wood-deck. Water is an enemy to timber. Prolonged exposure to water makes wood susceptible to a damaging fungus commonly known as timber rot. Affected wood appears discolored, crumbling and stringy and feels spongy or soft. Rotted timber looks bad and can be a danger because the wood rot weakens the structure, which can give under the weight of the deck or people on the wood-deck. timber rot can also spread from the deck to other wood areas such as door or window sills, siding and even the house’s framing. Removing the existing rot and repairing the wood-deck is required in order to maintain the structural integrity and visual appeal of the deck.

 Inspecting the wood-deck for timber Rot

Remove any coverings from the wood-deck boards. If you have furniture on the deck, move it to one side while you inspect.

Start with the timber railings – look for areas that appear different from the rest of the railings. Wood rot may appear to be a different color or look like it’s crumbling. If any part looks suspicious, err on the side of caution and treat it as if it is rot. Circle the area with a piece of chalk. Do not use red chalk it will stain the wood-deck.

Move to the deck boards – you may have to crawl around on your hands and knees looking for anything suspicious. Any areas that look like they may have timber rot, take a thin bladed flat chisel and lightly pick at the area. If the timber crumbles away or the chisel easily sinks into the wood, circle the area with chalk and repair it.

Look at the upright supports and then the joists – joists are pieces of lumber that support the deck boards. Circle any areas that look like they may have rot.

Repairing the timber Rot

Put on safety goggles, work gloves and a pair of kneepads.

Hold a mortise chisel, bull chisel or framing chisel at a 45 degree angle to the rotted area. Place the chisel 1 inch from the obvious rot and tap it with a mallet break out the damaged wood. Continue to chip away at the rotted timber until you reveal solid wood. If you found rot on an upright support or joist that penetrates the wood more than 25 percent of the way through – replace the joist or support as it will lack the necessary strength to hold up the deck.

Vacuum up the debris with a shop vac.

Dip a paintbruh into an wood rot-inhibitor, also known as wood stabilizer.

Brush the rot inhibitor into the area where you chipped away the rotted wood and the 18 to 24 inch area surrounding it. If you prefer, you can paint all wood surfaces with the rot inhibitor as a preventative measure.

Apply wood rot-inhibitor to the surrounding wood surfaces. Paint the rot-inhibitor on in several layers. Continue to add layers until the wood no longer absorbs the inhibitor. Treat surface 1 to 2 feet from the existing rot outward. You can paint the entire structure with rot-inhibitor if it is in danger of developing rot.

Continue to add thin layers of the wood rot inhibitor until the wood will no longer absorb the inhibitor. This may take two to three coats up to 10 to 12 coats.

Let the wood rot inhibitor dry completely, this may take one to two days to dry. You will know when the inhibitor is dry when it no longer looks wet.

Dip a paintbrush into an epoxy based penetrating wood sealer and paint the base of the recessed area, uprights, rails, spindles and joists.

Pour the wood sealer into a painter’s tray and roll a ½ inch nap paint roller through the sealer.

Roll a coat of wood sealer onto the deck boards.

Let the sealer dry for three to four hours or until it is no longer tacky.

On a disposable plastic plate -- mix two part epoxy repair putty according to the putty manufacturer’s directions or use epoxy repair paste.

 Scoop up the repair putty or paste onto a flexible plastic putty knife.

Press the putty or paste into the base of the chipped out area in thin layers. Continue to add layers up the paste or putty sits about 1/8 inch higher than the wood. Layers of epoxy repair paste or putty forms a stronger repair than one big glob stuck in. If the carved area sits on an edge of the deck, upright, post or rail, form the putty to the same shape as the section you are rebuilding. Wear gloves to protect your hands from the repair putty.

 Let the epoxy paste or putty dry for one to two hours, depending on the thickness of the repair. Press on the dried paste or putty, if it has any give want another hour or two and try again.

Wrap 100-grit sandpaper around a sanding block and sand the repair paste or putty surface until it is smooth and level with the surrounding wood.

Tips for Preventing Wood Rot on a Deck

Keep your wood deck sealed with penetrating wood sealer to keep the fungus spores that cause wood rot away from the wood.

Keep bushes, trees and other vegetation trimmed back from the deck and upright supports to provide proper ventilation.

Keep gutters clean and fix gutter leaks to keep excess water off the deck.