The Soft Board Is Never Just the Board: Spotting Deck Water Damage in June
Most deck failures in Clark County start the same way: one board that flexes underfoot. Here is how to read the signs, and why June is the month to catch them.
Here is how to tell if your deck has water damage without guessing. Look for boards that feel spongy or give underfoot, gray or black discoloration spreading from the joints, boards that are cupping or splitting, fasteners that have popped up or rusted, and any spot where a screwdriver sinks into the wood instead of meeting resistance. The checks that matter most are where the deck attaches to the house and where the boards rest on the supports underneath, because that is where water sits longest and where damage costs the most.
Most deck failures we see in Clark County start the same way. One board flexes a little when you walk across it. The homeowner notices, figures it needs a new plank, and books the repair. Reasonable read. It is also, often, the visible end of something larger.
Here is how that plays out. The board itself is an easy fix. But when the gray streaking runs along the seam where two boards meet, and the support beam underneath that seam is dark and damp, you are not looking at a board problem. You are looking at water that has been wicking down through the gap between the boards all winter, sitting on top of the framing that holds the whole deck up. The surface looks fine from a lawn chair. The structure can be a few soft years from a real problem.
That is the thing about deck rot in the Pacific Northwest. The deck does not fail where you can see it. It fails underneath, where the wood stays wet and shaded and nobody looks. The USDA Forest Products Laboratory's Wood Handbook puts a number on it: decay fungi need wood moisture above roughly 20 percent to grow, and shaded, ground-level deck wood stays wet far longer than that through our winters. Keep it drier than that and it does not rot. [1]
The signs, in plain terms
Spongy or springy boards
Sound decking feels solid. If a board flexes, gives, or bounces under your weight, it has absorbed water and started to break down inside.
Gray or black discoloration
Healthy wood weathers to a soft silver. Rot is darker, often blackish, and it tends to spread out from joints, fastener holes, and the ends of boards.
Cupping, splitting, and cracking
Boards that curl at the edges or split along the grain have been through repeated soaking and drying. Each cycle opens the wood up to more water.
Popped or rusted fasteners
When the wood around a screw or nail swells and shrinks, the fastener works loose. Rust streaks also tell you water has been sitting there.
The screwdriver test
This is the honest one. Press a screwdriver or an awl into the wood at the spots that worry you, especially near the house and at the base of the posts. Firm wood resists. If the tip sinks in with light pressure, that wood is gone.
Why June is the month to find it
Caught now, that kind of repair is contained: replace the damaged board, treat and protect the beam below, close the gap that let water through, and reseal. It takes part of a day and keeps the deck sound.
The same deck, found in October, is a different job. By fall the beam has had another wet season to soften, and rot in a support member does not stay put. It spreads to the boards bolted to it. One soft beam becomes several. A part-of-a-day repair becomes a structural one, with more wood, more labor, and a deck you can't safely use until it's done. The difference between the two jobs is not the damage. It is the timing.
This is why we tell people the dry season is for looking. A deck inspection in June, when the wood is dry enough to read clearly and there is still time to fix what you find, is one of the highest-value half hours a deck owner spends all year.
What to do this week
Walk your deck and run through the list above. Spend the most time where the deck meets the house and at the base of the posts. If everything is firm, seal it and enjoy your summer. If you find a soft spot, don't wait for it to get worse. It will, and it gets more expensive every month the rain is gone and you let it sit.
Want someone to check the parts you can't see? We will tell you honestly whether you have a small fix or a real one, with no upsell. Call (360) 838-6731 or schedule a deck check. Schedule a Deck Check