Why Protecting Deck Foundation Matters

Beautiful deck tape

Any home improvement project is a significant undertaking. When building a deck, you'll be concerned with how it looks, how it complements your home, and how you interact with it. It's your project, and you want it to go right.

However, to get the maximum fulfillment from your new deck, you need to take steps to ensure it lasts. If you don't take care of it properly, your deck's foundation can rot in less than ten years.

Of course, there are ways to prevent this, and if you do them correctly, you can create something that will last as long as your home itself. To ensure your deck stays sturdy for as long as possible, follow these three key steps: protect, clean, and seal.


The best way to protect your deck is to take measures during construction. Water damage is wood's worst enemy, leading to rot, which compromises structural integrity. According to research, a deck will usually begin to rot after about 8 to 10 years if not properly treated.

However, this is preventable by applying butyl tape like this, to the wood foundation during construction. Butyl tape protects against moisture that seeps through the decking boards. Without it, the joists and beams used to build your deck are repeatedly exposed to water. Constant water exposure will cause the wood to deteriorate. In addition, once the water seeps in, it can rot out the wood and rust the screws.

Using deck tape

Butyl tape is very easy to apply. It works as a cap for your wooden joists and beams to provide a protective barrier. It also helps protect the ledger board, the area where your deck connects to the side of your house. Trex Protect makes butyl tape designed for decks and other minor home fixes.


While joist protection tape ensures your deck's substructure last for a long time, regularly cleaning the deck surface is also recommended. Dirt and debris can collect moisture if left unswept. Also, potted plants on your deck can trap moisture as well.

cleaning deck tape

You can clean the deck surface easily with water, soap, and a scrub brush. For certain stains, a power washer may be necessary. However, be careful as power washing can sometimes splinter and damage the wood. If the wood is already damaged, power washing will only exacerbate the problem. It can also cause damage to composite decking, though it's a bit more durable than lumber.

To clean the deck with soap and water, follow these simple steps:

  1. Remove all furniture, plants, etc., from the surface of your deck.
  2. Sweep away any dirt, leaves, dust, etc., from the deck.
  3. Test the cleaner on a small area to ensure there is no staining.
  4. Clean with water, soap, and a scrub brush.
  5. Rinse off thoroughly with a hose.
  6. Let the deck dry completely before moving back any furniture.

To clean with a power washer, follow these steps:

  1. Keep the nozzle at least two feet from the surface of the deck.
  2. Use a fan tip attachment and soap dispenser.
  3. Rinse thoroughly. If the water used for cleaning is left to dry, it will leave a layer of film on the surface.

Stain or Seal

Sealing the deck boards is the final step in protecting your deck from water sinking into the foundation. Sealing helps reduce the amount of water the wood is exposed to, keeping it safe from the elements so it won't crack or grow mold.

Sealant is typically clear, while stain will color the wood, giving it a richer look. A sealant requires regular reapplication, somewhere between once per year or once every three years, depending on the use of your deck. Composite deck boards do not need to be sealed.

It's also very important that you try and do your cleaning and staining/sealing all in one day. Find a bright and sunny day so that the sunlight will naturally dry your deck in-between steps.

For steps on applying sealant:

  1. First, ensure the temperature is between 50 and 90 °F. Better weather means a better seal.
  2. Like with cleaning, move all furnishings and anything else from the surface.
  3. Sand down the deck surface to ensure that the sealant forms an adequate and consistent layer of protection. Be sure to clean off all the sawdust.
  4. Stir (do not shake) your sealant.
  5. Use a brush, paint roller, or sprayer for application. Apply thin coats in two to three board sections. You can always add another thin coat later as it will apply and dry better than one thick coat.
  6. Always make sure your deck dries completely before returning anything to its surface.

Always keep an eye on your deck between seasons for any signs of wear and tear, and make a note of when you last applied sealant. With summer right around the corner, now is a great time to get ahead and start prepping your deck!

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