Customer Service: (253) 677-0290
Customer Service: (253) 677-0290
By Daniel Rotaru, owner of Decks Restore. Washington contractor license CC DECKSRL797P2. Building and maintaining decks in Maple Valley and the South Sound since 2011.
Every deck maintenance article I have ever read tells you to do the same two things: clean it in spring, and seal it every couple of years.
That advice was written for a climate where decks dry out. Ours do not. A Maple Valley deck under Douglas fir spends roughly eight months of the year damp, takes needle drop more or less continuously, gets buried in big-leaf maple leaves in autumn, and sees a three-week pollen event in late spring that coats everything in the garden. The useful schedule here is nothing like the generic one.
After fifteen years of maintaining decks in this climate we have ended up with three dates, and each one exists because something predictable happens around it. Miss the October job and the deck spends five months unable to drain. Skip February and you find in May what you could have caught in February, usually for more money. Lose May and you have lost the only stretch of the year when wood is dry enough to take a finish.
Our wet season runs roughly from late October through to the end of April, and it is persistent rather than dramatic. Not many storms, just months of steady rain and overcast with very little drying in between. Surfaces stay wet. Anything that holds water holds it for weeks rather than days.
October is the last moment the deck is reliably dry enough to work on before that season starts. Anything you want to clear, clean or fix has to happen before the rain settles in, and in a normal year you have a usable window from late September to about the third week of October.
February is the worst of it. Deepest into the wet season, lowest light, most moss growth, and the point at which any drainage problem has had three months to show itself. It is also a miserable time to be standing in the garden, which is why almost nobody looks at their deck then, and why problems go unnoticed until they cost money.
May is when the deck finally dries out, the conifer pollen finishes, and you get the first honest look at what the winter did. It is also the only part of the year when a wood deck will be dry enough to take a finish properly.
If you only ever manage one of the three, make it October. Almost everything that goes wrong between November and April starts with water that cannot get off the boards.
Budget two to three hours. Pick a dry day in the first three weeks of the month, before the maple leaves have all come down but after the worst of the needle drop.
Start with the gaps between the boards. That half hour is worth more than everything else here put together. Fir needles stand on end and wedge down into the gap, and once they pack it the deck stops draining. A thin putty knife, a plastic shim or a stiff wire run down each gap will clear them. A leaf blower on its narrowest setting does most of the work faster, though you will still want the blade for the stubborn sections.
Then the ledger line, where the deck meets the house. Debris collects against the flashing and sits there holding moisture against the siding until April.
While you are down there, look at the downspouts. Any one discharging within a few feet of a deck post wants dealing with before the rain settles in, and if water is running out onto the ground near a footing, October is the month to extend it.
Sweep the surface and clear underneath. Leaves left on the boards through a wet November leave tannin marks, worse on lighter composite and on any wood deck, and leaves piled below hold moisture against the framing.
Lift what you can. Planters, mats, anything sitting flat on the boards. A rubber-backed mat left down from October to April produces a dark rectangle and sometimes a patch of rot. If a planter has to stay out, put it on feet.
Last, trim whatever overhangs. Branches directly above drop more onto a deck than any other source, and a light cut back now takes most of the February problem away with it.
Skip the month and the deck spends the whole winter unable to shed water, which is how you end up with moss along every board edge, a surface that is slippery from December onward, and framing that never dries out.
February is a looking job rather than a cleaning job, and it has to happen in February because the things you are looking for only show themselves when the deck is thoroughly wet.
Put a coat on, go out during or just after heavy rain, and check five things.
Where the water is sitting. A deck that drains has nothing standing on it half an hour after the rain stops. Puddles mean the gaps are blocked, the boards have cupped, or the framing has settled. Note where they are, because that information is worth a lot in May.
Where water is coming off the roof. A downpour shows you things that are invisible in July. A gutter overflowing onto one corner. A downspout discharging onto the ground near a post. A sheet of water running off the same edge onto the same strip of soil every time it rains.
Moss, and where it is growing. It starts along board edges and in the corners that never see sun, and February is peak growth. Caught now it is a light brushing job. Left until May it has had three more months to establish itself.
Anything that feels different underfoot. Walk the whole deck. A soft spot or a bounce that was not there in September is coming from the framing rather than the surface.
Whether the gate still latches. Sounds trivial. A gate at the top of the stairs that latched in October and binds in February is telling you something has moved, and that kind of seasonal travel usually traces back to a footing. We went into why in clay soil and footing heave in Maple Valley.
Write down what you find, somewhere you will come across it again in three months. In May you will want to compare.
Budget half a day. Wait until the fir pollen has finished, which is usually the second half of the month, because washing a deck in the middle of pollen season means doing it twice.
Wash it first. A deck brush, a garden hose and a bucket of cleaner suited to your surface. Work with the grain, rinse thoroughly, and do not let the cleaner dry on the boards. That takes off the winter’s moss, algae film and tannin staining in one go.
On a deck that grows moss every year, brushing only removes what you can see, so a proper moss treatment does more. May is better than autumn for it because the surface will actually dry afterwards.
Now go back to your February notes. Puddles that showed up then should have a cause you can see on a dry deck: cupped boards, a blocked gap, a low spot in the framing. This is where the twenty minutes in the rain pays off, because you are diagnosing in daylight instead of guessing.
May is also when the annual structural walk happens. Railings, stairs, the ledger, post bases. Our 7-point deck safety checklist covers what to look at in what order, and the month suits it because everything is dry and visible.
If the deck is wood, this is your finishing window. Stain and sealer need the wood genuinely dry, which here means several consecutive dry days beforehand and ideally a couple after. That window realistically opens in late May and runs to September. Finish applied over damp wood traps the moisture underneath and lifts within a season, so if you miss May, go in July rather than forcing it.
Then put the furniture back on feet. Anything sitting flat on the boards all summer leaves a mark, and small rubber or plastic feet under table legs and planters cost almost nothing.
The calendar does not change. The May job gets shorter and what is at stake changes.
Composite does not rot, so a missed cleaning costs you appearance rather than structure. What it does do is grow surface mould and algae on the film of pollen, needles and dust that settles on it, which is why a composite deck under trees here looks dirtier than clients expect. The board underneath is fine. The layer sitting on top of it is alive.
Four things work differently.
No sealing, ever. Nothing to apply, and products that claim to seal composite generally do more harm than good.
Use a composite-specific cleaner rather than a wood deck cleaner, and check the manufacturer’s list. Some composite warranties specify what you may use, and the wrong chemistry can mark a capped board permanently.
The gap clearing in October matters more, not less. Composite boards are typically installed with tighter spacing than old cedar decking, particularly on clip-fastened decks, so they block faster. We get into why the spacing varies in hidden fasteners versus face screwing.
Scratches do not sand out. A capped composite board that gets gouged stays gouged, which is a reason to be disciplined about furniture feet and about dragging planters.
For a cedar or pressure treated deck, the opposite emphasis applies. The May finishing window is the thing that determines how long the deck lasts, and skipping it for two or three years in a row is how a fifteen-year deck becomes a nine-year deck.
Whatever you put on your deck runs off it. On most Maple Valley lots that water goes into the soil and from there toward the Cedar River system, which is salmon habitat and part of the drinking water supply for a large part of this region. King County’s work on stormwater pollution makes the scale clear: an estimated 118 billion gallons of polluted stormwater goes untreated each year across the county, and it is now a bigger threat to local waterways than sewage, with yard chemicals named among the contributors.
One deck cleaning is a small thing against 118 billion gallons. It is also one of the easier contributions to avoid making.
Chlorine bleach is the one to avoid. It kills the moss, and it also kills whatever it lands on in the surrounding beds, degrades the lignin in wood decking so the surface fuzzes, and corrodes fasteners over time. Oxygen bleach, sodium percarbonate, does the same job on a deck without the same downstream problems.
Check what a product says about aquatic toxicity, not just what it says about decks. The phrase to look for on the label is whether it is safe around plants and waterways.
Rinse into planting beds rather than toward a storm drain where you have the choice. Soil filters. A storm drain does not.
Use the least aggressive thing that works. On most decks here, warm water, a stiff brush and a modest amount of the right cleaner removes everything a harsher chemical would, and takes about the same amount of time.
Most of the deck damage I see that was caused by maintenance rather than weather comes from one of these.
Pressure washing at full power is the first. In the wrong hands a washer erodes the soft spring growth out of cedar and fir and leaves a furred, grooved surface that then holds water and dirt worse than it did before. On composite it can breach the cap on cheaper boards. If you use one, keep it under about 1,500 psi, fit a wide fan tip, hold it a foot off the surface and keep it moving with the grain. Most decks here do not need one at all.
Sealing a damp deck is the most common spring mistake we see. The surface looks dry after two sunny days while the wood underneath is still carrying winter moisture, the finish goes on and traps it, and the coating lifts within a season. Then you are stripping it off and starting again. Wait longer than feels necessary.
Sealing on a hot afternoon fails the other way. Finish applied to a sun-heated board flashes off before it penetrates and sits on top as a film. Early morning, or a dry overcast day, beats full afternoon sun.
Carpet, outdoor rugs and artificial turf left down year round hold water against the boards continuously. On wood that is the fastest route to rot I know of outside an outright drainage failure, and on composite it produces discolouration that does not come out. If you use a rug, lift it in October with everything else.
One more I will add because it comes up every year: do not power wash to remove moss and then do nothing else. You have taken off the growth and left the spores and the damp conditions. It regrows faster each time, and on wood you have opened the surface up for it.
Most of this calendar is a homeowner job, which is an odd thing for a deck contractor to write, so it is worth being clear about which parts are not.
Do it yourself: the October clearing, the February walk-around, the May wash, furniture feet, gap clearing, basic moss brushing. None of it needs a trade, and the October and February jobs are far more valuable done by someone who sees the deck every day than by someone who visits once.
Worth paying for: refinishing a large wood deck, because the prep is the job and doing it properly takes equipment and a weather window most people will not wait for. Anything involving ladders on an elevated deck. And any structural work at all.
The line between maintenance and repair sits roughly here. Anything on the surface is maintenance. Anything involving the framing, the footings, the ledger or the guards is repair, and cleaning it will not improve it.
Things that mean stop and call someone: a soft or springy area underfoot, a railing with any play in it at hand height, a post that is no longer plumb, rust staining or a gap at the ledger where the deck meets the house, visible rot at any post base, or a deck that has dropped at one corner. Those are the calls we take as deck contractors in Maple Valley, WA, and the assessment is free. Sometimes the answer is that the deck is fine and you should carry on with the calendar.
This sits inside the May job, but it is worth pulling out, because it carries the safety consequences and most people never do it.
Decks fail at their connections. The places to look are wherever one thing is attached to another.
Start at the ledger, where the deck meets the house, and look for rust staining, gaps, any sign the flashing has failed, and bolts rather than nails. That connection is involved in most serious deck collapses.
At the post bases, check for rot where the post meets concrete or soil, and whether the posts are still plumb.
Guards next. Push firmly outward at the top of each railing post. Any noticeable movement means the attachment needs attention. These are what stop someone going over the edge of an elevated deck, and they degrade quietly.
On the stairs: treads solid, stringers not split at the cut notches, handrail firm, and the bottom step sitting on something solid rather than on dirt that has settled away from it.
If you can get underneath, look for hangers with missing or backed-out nails, joists split at the hanger, and staining that shows water running somewhere it should not.
A deck from the late 1990s, which describes a very large number of Maple Valley decks right now, is at the age where these connections start failing. The ones that get checked annually get fixed for a few hundred dollars. The ones that do not get found by a surveyor during a house sale, or worse, by someone leaning on a rail.
| When | Time needed | What you are doing | Why this month |
|---|---|---|---|
| Early to mid October | 2 to 3 hours | Clear gaps and ledger line, sweep, check downspouts, lift mats and planters, trim overhanging branches | Last dry window before the wet season; needle and leaf drop are peaking |
| February, during rain | 20 minutes | Look for standing water, roof runoff, moss, soft spots, a gate that has started binding | Problems are only visible when the deck is thoroughly wet |
| Late May | Half a day | Wash, treat moss, check February’s notes, full structural walk, seal if wood | Pollen has finished, deck is dry, finishing window is open |
| Any time | Minutes | Sweep off leaves and needles after a storm | Debris left to sit is what causes most staining |
That is roughly six hours a year on something that costs 30,000 dollars or more to replace.
For most wood decks here, every two to three years, and the timing matters more than the frequency. Apply it between late May and September when the wood is genuinely dry after several consecutive dry days. A deck sealed on schedule but applied to damp wood will fail faster than one sealed a year late under the right conditions.
Late May, after the conifer pollen finishes. Washing earlier means doing it again. A second lighter clean in October before the wet season helps but is optional; the gap clearing in October is the part that is not optional.
You can, carefully, and most decks here do not need it. Keep it under about 1,500 psi with a wide fan tip, held a foot off the surface and moving with the grain. Too much pressure erodes soft growth out of cedar and fir and leaves a furred surface that then holds dirt and moisture worse than before.
You cannot stop it in this climate, you manage it. Clearing debris in October removes what it grows on, improving airflow and drainage removes the conditions, and a moss treatment in May rather than autumn gives the surface a chance to dry afterwards. Trimming overhanging branches does more than any product.
Less, not none. No sealing, but the same October gap clearing, the same May wash with a composite-appropriate cleaner, and the same annual structural check, because the framing underneath a composite deck is still wood.
Chlorine bleach, which damages wood fibres, corrodes fasteners and harms planting and waterways. Rugs or artificial turf left down year round. And any cleaner your decking manufacturer’s warranty does not approve, which on capped composite can mark the board permanently.
We build, restore and repair, and we do the jobs on this calendar that are worth paying for, like refinishing a large wood deck or anything structural. The October and February tasks we would rather you did yourself, because you will catch things earlier than any annual visit would. We work across Maple Valley, Covington, Kent, Renton and Issaquah.
Mid-October, some wet day in February, late May. Set the three to repeat annually and you will be doing more for your deck than most people in Maple Valley manage, for about six hours of the year.
The decks we get called out to replace early are almost never the ones that were built badly. They are the ones where water was allowed to sit somewhere for ten years because nobody cleared a gap or moved a downspout.
If your February look turns up something you are not sure about, or if your May structural walk finds movement at a post or play in a railing, we will come and look at it at no charge and tell you honestly whether it needs work now, needs watching, or is fine.
Decks Restore LLC, Washington contractor license CC DECKSRL797P2, licensed, bonded and insured. Serving Maple Valley and the surrounding King and Pierce County communities.
Call (253) 677-0290 or request a free quote. Restoration and repair projects are in our gallery.