To pressure wash a deck, it is important to use the right nozzle, keep the pressure low, and move in smooth, even strokes. If done correctly, you’ll remove dirt, mold, and old stains without damaging the wood.
This step-by-step guide will walk you through the process, from prep to the actual washing and drying. To get a DIYer’s perspective, I spoke with my colleague Sarah on the subject. She and her dad pressure wash their family home, and the two of them have learned several tips and tricks that will help you avoid common mistakes and get pro-level results.
| Project difficulty: Easy to Intermediate Estimated time to complete: 30 minutes to 2 hours (depending on deck size and condition) Drying time: At least 24 to 48 hours before applying stain or sealant Project cost: $20-$100+ (depending on equipment rental and cleaning supplies) |
Pressure Washing vs. Power Washing Your Deck
Decks get dirty fast. Rain, dirt, and foot traffic wear them down. Over time, they look dull and worn. A deep clean brings them back to life. But should you pressure wash or power wash? The guide below can help you choose.
| Feature | Pressure Washing (Best for Routine Cleaning) | Power Washing (Best for Heavy-Duty Cleaning) |
| Water Temperature | Cold water | Heated water |
| Cleaning Power | Blasts away dirt, dust, and mildew | Breaks down tough stains, grease, and thick mold faster |
| Best For | Routine deck maintenance, light to moderate grime | Deep-set stains, oil spills, heavy mold/algae buildup |
| Safety for Wood | Safer and less risk of damaging wood fibers | Higher risk of wood damage due to heat and pressure |
| Equipment | Standard pressure washer (electric or gas) | Requires a commercial-grade washer with a heating element |
| Affordability | More affordable and widely available | More expensive and often requires professional service |
Which One Should You Use?
Use pressure washing if:
- Your deck has dirt, mildew, or light stains.
- You have a wood or composite deck that needs regular cleaning.
- You want a safer option that won’t damage the wood.
Use power washing if:
- Your deck has deep-set mold, grease, or years of buildup.
- The stains aren’t coming off with cold water and detergent.
- You have experience using high-heat pressure washers.
See Related:
Supplies Needed
Gathering the right tools before starting saves time and prevents mistakes. Here’s what you’ll need:
Pressure washer
This can either be:
- Electric: lighter, quieter, and easier to handle; good for routine cleaning
- Gas-powered: Stronger, better for deep cleaning, but louder and heavier
Nozzles
- 40-degree (white tip): widest spray, safest for wood
- 25-degree (green tip): stronger, good for tough stains, but requires caution
- Soap nozzle (black tip): used to apply detergent
Sarah notes that pressure washers usually come with multiple nozzles, and choosing the right one is crucial. Too strong, and you risk damaging your deck. If you’re unsure, start with the widest spray and test a small area first.
Detergent (Recommended for a Deeper Clean)
- Deck-safe (formulated for wood or composite)
- Never use bleach-based cleaners as they damage wood and weaken fibers.
Additional Supplies
- Stiff-bristle brush (for scrubbing between deck boards and railings)
- Eye and ear protection (safety glasses and earplugs to shield from debris and noise)
- Work boots, goggles, and gloves (for protection); ear protection (if using gas-powered pressure washer)
- Plastic sheeting (to cover plants, electrical outlets, and light fixtures)
- Garden hose (for pre-rinsing and post-cleaning)
How to Prep
Prepping right saves you headaches later. It keeps your deck safe, makes cleaning easier, and stops you from soaking things you didn’t mean to.
- Move Everything Off the Deck
- Take everything off (chairs, tables, rugs, planters, even the grill).
- If it’s too big to move, cover it with a tarp and weigh the edges down.
- Store things away from the deck (not just off to the side) so they don’t get splashed.
- Protect Everything Around the Deck
- Cover plants and flowers with plastic sheeting. Secure it so the wind doesn’t blow it away.
- Wrap outdoor lights, power outlets, and doorbells with plastic and painter’s tape. One stray spray, and you’re dealing with an electrical issue.
- If your deck is against your house, cover the lower part of the wall to keep dirt from splattering up.
- Sweep and Get Rid of Loose Debris
- Sweep off leaves, dirt, and twigs. A leaf blower works great, too.
- Check between the boards. If you see dirt packed in, grab a putty knife or screwdriver and scrape it out.
- If you spot moss or mildew, loosen it up first and don’t rely on the pressure washer alone.
- Fix What Needs Fixing
- Look for loose nails, screws, or boards. Tighten or replace them.
- Check for splinters or peeling paint. Pressure washing can strip it further, so be ready to sand or repaint after.
- If you see rotten wood, replace it now. High pressure will just rip it apart.
- Close Windows and Doors
- Double-check that all doors and windows are shut.
- If there’s a draft, shove a towel at the bottom of the door.
- Check the Wind Before Spraying
- Stand upwind so the spray doesn’t come right back at you.
- Be mindful of where detergent mist is going. You don’t want it landing on windows, siding, or plants.
- Set Up the Pressure Washer Properly
- Put it on solid, level ground (driveway, patio, or a flat surface).
- Keep the hose untangled and away from walking paths (tripping over it mid-wash is a bad time).
- If you’re using an electric pressure washer, plug it into a GFCI outlet. (wet + electricity = danger)
- If you’re using a gas-powered pressure washer, never refill the gas while the machine is hot. The muffler also gets extremely hot, so keep the hose and any flammable items away.
- Your Safety First
- Wear sturdy shoes, gloves, and eye protection. Sarah’s dad emphasizes that a focused stream of water can be dangerous if it hits your skin.
- Another tip from Sarah: if using a gas model, wear ear protection — it’s much louder than electric ones.
Steps to Pressure Wash Your Deck
Step 1: Test the Spray First
- Keep the nozzle at least 6 inches from the wood.
- Use the 40-degree nozzle for softwoods like pine or cedar.
- Use the 25-degree nozzle for hardwoods, but maintain a safe distance.
- Spray a small, hidden area to check for damage. Sarah’s dad warns that using a nozzle with too focused a spray can crack or pit the wood. Always test before going full force.
Step 2: Apply Deck Detergent (Optional but Recommended)
Note: While applying detergent is optional, it is recommended for decks to help loosen dirt and mildew for an even clean.
- Switch to a soap nozzle designed for detergent application.
- Spray detergent evenly, covering a few boards at a time.
- For vertical surfaces, start at the bottom and work upward to avoid streaks.
- Use a stiff brush for tight spots, like railings and corners.
Step 3: Let the Detergent Sit
- Follow the manufacturer’s instructions for wait time.
- Avoid letting it dry out and work in the shade if possible.
Step 4: Flush the System
- Rinse out the detergent from the pressure washer before switching nozzles.
Step 5: Wash the Deck
- Attach a 40-degree or 25-degree nozzle depending on wood type.
- Keep the spray wand 8 to 12 inches from the surface.
- Use long, sweeping motions along the wood grain.
- Overlap each pass slightly for even cleaning.
- Keep the nozzle moving. Staying in one spot too long can gouge the wood.
Deck PSI Settings:
- 500-600 PSI for softwood (cedar, pine)
- 1,000-1,200 PSI for hardwood (oak, ipe)
Bonus Tip: Sarah and her dad have found that for large surfaces, a rotary brush attachment speeds up the cleaning process. It provides even coverage and reduces the risk of wood damage from a concentrated spray.
Step 6: Let It Dry
- Wait 24 to 48 hours before applying any stain or sealant.
- If the wood feels rough after drying, sand lightly before staining.
If you’re tackling more than just your deck, check out these related guides:
FAQ
It depends on the deck size and condition. On average, pressure washing a deck takes 30 minutes to 2 hours. If using detergent or tackling heavy grime, expect longer.
Yes, but use 500 to 1,200 PSI and a 40-degree nozzle to prevent damage. Keep the wand 8 to 12 inches from the surface and move in long, even strokes.
Yes, but use 500 to 600 PSI and a detergent made for composite decking. Rinse thoroughly to avoid streaks.
Yes, but high pressure can strip paint. Use under 600 PSI if you want to keep the paint. If you are removing paint, higher pressure may help. Always test a small area first.
Yes, but pressure washing can fade or remove stains. Use under 1,000 PSI if you want to keep the stain. If you’re re-staining, pressure washing is a good step to prep. Let the deck dry fully before applying new stain.
Decked Out and Looking Fresh
A clean deck makes all the difference. It brightens up your outdoor space and extends the life of the wood. By prepping properly, using the right pressure, nozzle, and techniques, you can refresh your deck without causing damage.
Once it’s clean and dry, your deck is ready for whatever comes next — staining, sealing, or just kicking back with a cold drink.
Home Gnome delivers the best home service experience at the click of a button. Book reliable, skilled handymen and handywomen in seconds and leave the rest to us.
What to Read Next:
Main Image Credit: bubutu / Adobe Stock Free / License
Related Posts:
