Paver and pool deck maintenance in Maryland is not really about the pavers. A concrete or clay paver is a pressed, high-strength unit that will outlive the house. What fails is the joint between them — a quarter-inch of sand doing structural work, washed out a little more by every storm, every pool splash-out and every pass of a pressure washer held too close. Keep the joints full and a deck we lay in Potomac looks the same in year fifteen. Let them empty and you are paying to relay it.
01 / What actually failsPavers outlive their joints.
An interlocking paver system works because the units transfer load sideways into each other. That transfer only happens through packed joint sand. Once the joints empty, every paver becomes an individual stepping stone sitting on loose bedding sand — and that is when edges chip, units rock underfoot and water starts cutting channels through the bedding course instead of draining through it.
Around a pool the clock runs faster. Splash-out is constant, chlorinated water is harder on sand and sealer than rainwater, and sunscreen and body oils leave a film that holds dirt. Here is the short list of what we actually find when we are called out to a tired deck in Bethesda or Rockville:
| What you see | What is causing it | What it needs |
|---|---|---|
| Open joints | Splash-out, downspout discharge, wash water, high-pressure cleaning | Re-sand and recompact; fix the drainage first |
| Green or black film | Algae, moss and lichen in shade — common under mature oaks in Potomac | Dedicated cleaner with dwell time, not more pressure |
| White haze | Efflorescence: free lime wicking out of new concrete pavers | Patience, or an efflorescence-specific cleaner |
| Dark greasy patches | Sunscreen, body oil and grill drippings bound into the paver face | Degreaser and poultice, before any sealer goes on |
| A paver that rocks | Bedding sand has migrated into a void or a settled base | Lift, re-screed, relay — a localized repair |
| A dip wider than one paver | Base failure, not a joint problem | Excavate and rebuild that section |
The first four are maintenance. The last two are repairs, and the distinction matters: a rocking paver is an afternoon, while a sunken section means the base is wrong and washing it will not help.
02 / The annual washClean it without stripping it.
One thorough wash a year keeps a deck looking new. In Montgomery County the right window is April or May — after the last hard freeze, before the pool opens. Shaded decks usually want a second, lighter pass in October to clear leaf tannin before winter sets the stain into the surface.
The risk is not dirt. It is the washing itself. A 3,000 psi machine with a narrow tip will strip every joint in a 600 square foot deck in about twenty minutes, etch the smooth face off concrete pavers, blow the chamfered edges into a rounded blur and drive water down into the bedding course where it does real damage. The surface will look brilliant for a season and then start moving. What actually works:
- Pressure in the 1,500–2,500 psi range, with a 25° or 40° fan tip — never a 0° or 15° tip on a paver face.
- Twelve to eighteen inches of standoff, kept constant. Closing the gap doubles the force on the surface far faster than most people expect.
- Chemistry before pressure. Organic growth needs a cleaner and five to ten minutes of dwell time. Pressure alone just moves it around and takes your joints with it.
- Work across the joints, not along them. Running the wand down a joint line excavates it.
- Rinse the pool and the beds. Cleaner runoff belongs nowhere near the water or your plantings, so wet both down first and flush after.
That is a narrow band to hold by hand across several hundred square feet, and the margin between a uniform clean and a visibly hazed stripe is a couple of seconds of hesitation in one spot. If you would rather not own that risk on a pool deck you just paid for, hand it to a crew that does it every day: a professional residential power washing service works off a rotary surface cleaner that rides on the deck and spreads the pressure over a wide disc, which is what delivers an even finish without carving out the sand. Either way, budget for re-sanding afterward. Every wash takes some joint material with it, and a deck left open for a few weeks of Maryland thunderstorms is a deck that starts to move.
Chlorine bleach, muriatic acid and wire brushes.
Bleach kills the algae and lightens the paver pigment underneath it unevenly. Acid etches the cement paste off the face and leaves a permanently rough, dirt-grabbing surface. Both can discolor the joint sand for good. Use the cleaner made for the stain you actually have.
03 / Joint sandThe one job most owners skip.
Re-sanding is cheap, fast and the highest-return thing you can do to a paver deck. The deck has to be dry, because damp joints pack badly and polymeric sand will haze on a wet surface. Sweep the sand in diagonally across the joints, run a plate compactor with a protective pad over the field to settle it, top up the joints that dropped, then blow every grain off the paver faces before you water it in. A single grain of polymeric sand left on a paver and activated will set there as a permanent white freckle.
On a pool deck, polymeric sand is worth the premium over plain masonry sand: it binds into a flexible solid, resists washout from splash-out and suppresses the weeds and ants that otherwise colonize open joints. It is not permanent — plan on a top-up every three to five years, sooner on the splash side. If you are choosing paver material for a new deck, the joint behavior differs between clay and concrete units, which we break down in our comparison of brick pavers and concrete pavers in the DMV.
04 / SealingOptional on pavers. Useful on pool decks.
Pavers are not stamped concrete. A stamped patio depends on its sealer, which is why we tell clients to reseal stamped concrete every two to three years without exception. Pavers carry their color all the way through the unit, so sealer is a choice rather than a requirement.
It is usually a good choice on a pool deck. A joint-stabilizing sealer locks the sand surface, a penetrating sealer makes sunscreen and grill grease release instead of soaking in, and both slow efflorescence. Three rules: never seal a deck inside its first year, while efflorescence is still working its way out; never seal a damp deck, because trapped moisture clouds the finish; and choose a matte or satin product on a pool surround, since a high-gloss film gets slick when wet.
05 / Settling and relaysWhen upkeep is not the answer.
A single rocking paver is a maintenance item: lift it with two putty knives, add or screed off bedding sand, set it back, re-sand the joints. A dip that spans several units is not. That is the base telling you it was built thin, compacted poorly, or is taking water from somewhere it should not — a downspout dumping at the edge, a pool backwash line, a neighbor’s grade. Re-sanding a sunken section just gives the water a tidier path.
The fix is to excavate that section, correct the drainage, rebuild the base in compacted lifts and relay the same pavers. Because pavers are reusable, a localized relay runs a fraction of a replacement — one of the real advantages of a unit paving system over a monolithic slab. We cover the numbers for new work and rebuilds in our breakdown of pool patio and deck costs in Montgomery County, and our pool deck installation page lists what goes into a base built to stay put.
06 / The calendarWhat to do, and when.
| Season | Task | Why now |
|---|---|---|
| Early spring | Walk the deck. Mark rocking units and open joints. | Freeze-thaw damage shows itself before anything is hidden by growth. |
| April–May | Full wash, then re-sand the joints. | Clean and tight before the pool opens and the season’s traffic starts. |
| Early summer | Seal, if the deck is due and dry. | Warm, dry, low-humidity stretches cure sealer properly. |
| Through summer | Rinse splash-out zones. Treat oil spots as they happen. | Sunscreen and grease bind to the paver face within days. |
| Fall | Clear leaves weekly. Light wash on shaded decks. | Wet leaf litter stains and feeds the next year’s algae. |
| Before first freeze | Top up any open joints. Check that downspouts discharge away from the deck. | Water sitting in an empty joint is what heaves pavers over winter. |
| Winter | Plastic shovel only. Sand or calcium magnesium acetate for traction. | Steel edges chip paver faces; rock salt attacks joints and nearby concrete. |
That is roughly one afternoon a year plus ten minutes a month, which is the entire argument for pavers over poured concrete around water: nothing in that list requires a contractor, and every step is reversible.
07 / Frequently askedPaver upkeep questions, answered.
How often should you pressure wash a paver patio or pool deck in Maryland?
Once a year, in April or May. Shaded decks under mature trees in Bethesda and Potomac often earn a second light pass in the fall to clear leaf tannin and algae before winter sets the stain. More frequently than that and you are removing joint sand faster than it is worth replacing.
Do paver pool decks need to be sealed?
No, but it helps. A penetrating or joint-stabilizing sealer makes the deck easier to clean, slows efflorescence and holds joint sand in place, and it needs renewing every three to five years. Do not seal a deck in its first year or while it is still damp.
Why do my pavers have a white haze on them?
Efflorescence. Free lime inside the paver dissolves in moisture, wicks to the surface and dries as a white salt film. It is normal on new concrete pavers, it is not a manufacturing defect, and it generally weathers off within a year or two. An efflorescence cleaner speeds it up; acid and extra pressure just etch the face.
Can I use rock salt on a paver pool deck?
Avoid it. Sodium chloride attacks joint sand and any adjacent concrete coping or steps, and it is what drives the surface spalling we see on older MoCo flatwork. Sand for traction, or calcium magnesium acetate where you need melting.
08 / Final wordKeep the joints full.
If you remember one thing from all of this: wash once a year, and re-sand every time you wash. Nearly every failed paver deck we are called to relay in Montgomery County traces back to joints that were allowed to empty, usually by well-intentioned high-pressure cleaning that nobody followed with a bag of sand. Everything else on the list — sealing, stain treatment, the seasonal walk — is refinement. If you want a second opinion on where your deck stands, we walk yards in Potomac, Bethesda, Rockville, Chevy Chase, Silver Spring and across Montgomery County at no charge.