When preparing to refinish your wood deck, using a chemical deck brightener applied by hand-scrubbing might not be sufficient for deep cleaning. In such cases, a pressure washer becomes a valuable tool. Unlike a chemical deck brightener, a pressure washer uses water alone but is highly effective at cleaning. However, it’s crucial to use the pressure washer correctly, as it has the potential to damage your deck if misused.
A pressure washer is a powerful machine capable of cleaning various surfaces, from etching brick to washing siding. If not used with care, it can be too forceful, causing deep etching and splintering of wood fibers. Familiarizing yourself with the machine and its settings is essential before applying its cleaning power to your deck. Taking precautions and using the right pressure and distance from the surface are key to achieving effective and safe cleaning results.
Instructions
Selecting the Right Pressure and Tip
Before using a pressure washer on your deck, choose the appropriate pressure setting and spray tip:
- Opt for the lowest effective pressure, around 500 to 600 psi for soft woods like cedar or pine.
- For harder woods, don’t exceed 1,200 psi.
- Use a fan tip with a 40- to 60-degree spread or a rotating tip if used carefully.
Testing Pressure Washer Settings
Prior to cleaning, conduct a test in an inconspicuous area to determine the right pressure:
- Begin with a pressure of 500 to 600 psi.
- Gradually increase pressure until finding the optimal setting.
- Test in an unseen area, such as a stair tread, to avoid potential damage.
Power Washing the Deck
When power washing your deck, follow these steps for effective and safe cleaning:
- Engage the trigger with the wand tip a couple of feet away from the deck, gradually lowering it as needed.
- Maintain a distance of at least six inches to prevent wood damage.
- Clean the deck with a sweeping motion, avoiding pivoting for consistent distance.
- Work from the house outward, moving with the grain and overlapping each area slightly.
- Feather the spray lengthwise for even cleaning and avoid creating “hot spots” or visible edges.
Sanding After Washing
When power washing a wood deck, it’s possible for the wood fibers to become raised and create a rough surface, particularly when the wood gets wet. This is more noticeable on handrails, where raised fibers can lead to splinters, necessitating some sanding for remedy.
Options for addressing raised fibers include:
- Spot-Sanding:
- If power washing caused minimal damage and you only want to clean the deck, spot-sanding may be sufficient.
- Address raised fibers selectively, focusing on problematic areas.
- Refinishing Preparation:
- If planning to refinish (re-stain or reseal) the deck, sanding the entire deck is necessary to ensure smooth boards with minimal splintering.
- Sanding also opens up the wood pores, allowing for consistent absorption of the sealer or stain.
- Ensure the wood is completely dry before initiating the sanding process.
- Sanding Recommendations:
- Avoid using very fine sandpaper, as it may clog the wood pores and impede the absorption of stain/sealer.
- For handrails, use sandpaper no finer than 100-grit.
- For the deck surface, opt for 60- to 80-grit sandpaper.
- A random orbit sander with a five-inch sanding pad is recommended for sanding wood decks.
By carefully sanding the deck, you can address raised fibers, create a smoother surface, and prepare the wood for effective refinishing, ensuring a consistent and well-absorbed sealer or stain.
