Project Guide

How to Prep a Deck for Stain

Why You Need to Prepare Your Deck Before Staining
A newly stained  wood deck next to a brick house.

No matter if you have a new deck or if you are working to restore a deck, the first step in how to prep a deck for stain starts with an inspection. Inspection should only take a few minutes. The results of the inspection will determine if a quick power wash is needed or something more involved.

Before You Begin
A person checking the weather forecast on a smartphone.

Prepping a deck for stain right before it rains will make the job last longer than it needs to. Check the weather in your area. Most stains require dry wood and a 24-hour window of dry weather in order to cure. Make sure you have all your tools and materials ready to go, just in case you have a short fair-weather window. 

Avoid high temperatures (above 90 degrees Fahrenheit) when you start your stain prep. If it’s too hot, the cleaner may dry too quickly causing uneven penetration. Temperatures below 50 degrees Fahrenheit lengthen drying time. Humidity isn’t a big issue, but it will take longer for your deck to dry. The perfect temperature for prepping a deck to stain it is between 50 and 89 degrees Fahrenheit on a low humidity day. For most areas in the country, spring and fall are the perfect times of year to stain your deck. 

Examine Your Deck's Condition
A person running a paintbrush between two deck boards.

Applying stain over a damaged wood will not improve the appearance nor protect the deck from the elements. Before you clean it, it’s important to perform a thorough inspection. Ensure there is no damaged wood and make sure that the structure is sound. 

  • For an existing deck, inspect the surface for popping nails or broken screws. Look for any broken or warped deck boards. Replace any nails, deck screws and wood boards as needed prior to cleaning.

  • Check any part of the deck that is in direct contact with the ground or connected to the house, including joists and beams. These areas are susceptible to water damage. Tighten any loose screws and replace any that are rusted. 

  • Check for rotting wood on the deck. Use an awl or screwdriver. Probe around posts where they make contact with the ground or foundation blocks. Any wood that is soft needs to be replaced before staining. 

  • Inspect the framing material (the ledger) that attaches the deck to the house. Make sure the flashing is in good shape with no holes or rust. The ledger should be attached with lag screws, not nails.

Test the Stain
A person rolling cleaner on to a deck.

If your deck is new and unstained or you already know what type of stain was used on your deck, you can move onto cleaning a deck before staining. However, if you have no idea if the stain on your deck was water-based or oil-based, you will need to perform a quick test. Water-based stains need to be stripped off before you apply a new finish, while oil-based stains can be recoated after you use a deck cleaner.

To test the stain:

  • Apply a small amount of deck stripper to a small area on your deck. Let it sit for about 15 minutes, then wipe it off with a cleaning rag.
  • If the stain comes off, the stain is water-based. Follow the directions on the deck stripper for removing the stain from the deck.
  • If the stain does not come off, the stain is oil-based.

Clear and Sweep
A person sweeping a deck.

Remove all your patio furniture and potted plants from the deck. Cover any landscape plants with plastic sheeting to protect them from the wood cleaner and spray from the hose or pressure washer. Thoroughly sweep the deck to remove all leaves and other debris. Once you remove dirt from the surface, prepare the cleaning solution.

Apply Cleaner
A person scrubbing a deck with a broom.
  • Mix the cleaner according to the manufacturer’s directions.
  • Apply cleaner to the wood deck using a roller or pump sprayer. Be sure to wear protective equipment to avoid contact with skin and eyes.
  • Allow the cleaner to sit for 15 minutes. If needed, mist the deck's surface with a garden hose to keep it wet while the cleaner soaks into the wood.
  • While the deck is wet, check for mill glaze (water beading which shows that the surface is not porous.) If mill glaze exists, either sand lightly, or scrub the area until water is easily absorbed into the wood.
  • While the deck is wet, check for black spots that might indicate mold or mildew (yes, even on new wood.) If you find mold or mildew, treat with an appropriate product.
  • After 15 minutes, use a scrub brush to work the cleaner into the surface. Scrub thoroughly to remove all residue.

Tip: If you have a large deck, work in small sections to make sure the area stays wet at all times.

A person pressure washing a deck.
  • Rinse the surface with a garden hose. Or, use a power washer equipped with a 45-degree tip set at 1200 to 1400 psi. Stay 8 to 12 inches from the surface of the deck and go with the grain of the wood. Clean like a pro with these pressure washing tips.
  • Allow the deck to completely dry. Once it's dry, use a sander on any areas of new wood to remove any remaining residue. 
  • Use a leaf blower or broom to sweep up any wood dust particles. 

Stain the Deck
A person applying stain to a deck.

Once your deck is clean, mold/mildew and splinter-free, and all previous coatings are removed, you’re ready to apply deck stain. Now that you know how to prep a deck for stain, it's time to apply a coat of your new stain on the surface of the deck. After the stain dries, apply a transparent stain sealer and allow it to cure.

Properly prepping a deck for stain will give you professional results. The Home Depot has deck ideas and ideas on planning a deck to create the ultimate outdoor living space. Get deck cleaning supplies and paint remover delivered to your doorstep. We deliver online orders when and where you need them.