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How to Prevent Deck Substructure Rot with Joist Tape

5 Simple steps to make your deck framing last just as long as your boards. 

These days a common goal with deck building is to install long-lasting boards that require little maintenance so homeowners can simply enjoy their outdoor living space. Popular composite boards even boast 30-year warranties. While your boards can go the distance, you have to ask the question: can the deck substructure?

If you’re using steel framing, then the answer is yes. However, most of the market uses pressure treated lumber for the substructure, and for good reason. It’s more readily available, accessible, and affordable, and great fastening systems make for easy connections. But the life expectancy of pressure treated lumber is around 15 years.

Luckily, there are 5 simple steps to follow that will help you prevent rot and extend the life of your deck substructure so you can enjoy your deck for decades to come.

  1. Prepare Your Framing

You will have to cut your treated lumber to the correct size for your project. The treatment in pressure treated lumber is only on the surface level, so as soon as you cut the lumber, the cut end is susceptible to water and insect rot.

To ensure proper treatment of your lumber, make your cuts and immediately use a sealant to treat the cut ends. Liberally applying a sealant will preserve the lumber and seal out moisture it comes in contact with.

  1. Properly Flash the Ledger Board

It’s critical to prevent water and moisture buildup where the deck connects to the house through the ledger board. Fine Homebuilding lays out a step-by-step process to properly install and flash the ledger board, but you should always check with local building codes for what is required in your area.

Typically, after removing the home’s siding, you will want to apply flashing tape to the house wrap, then secure your ledger board. Flashing tape ensures that water won’t get into the sheathing, as the tape will self-seal around the fasteners. Additionally, you can use more flashing tape on the top of the ledger board to direct water away from the house or use a combination of tape and metal or vinyl flashing strips.

  1. Use Joist Tape

Since water can get trapped between the deck boards and the joists, a simple and affordable preventative measure is using joist tape. This flexible flashing membrane acts as a moisture barrier wherever water could pool. 

There are various options on the market, but CAMO Joist + Ledger Deck Tape delivers reliable and affordable moisture protection for both deck joists and ledgers. It features a high-performance butyl hybrid adhesive with a high-strength non-slip polypropylene backing. CAMO Deck Tape will self-seal around nails and fasteners, blocking water from entering the wood and preventing wood rot and lumber breakdown. CAMO Deck Tape is made in the USA, backed by a 20-year warranty, and is available in three widths for job site convenience.

Plus, it’s super easy to install. Just ensure the surfaces are clean and dry, then peel back the release paper, apply the tape to the surface and press it into place, cutting the tape at your desired length. With joists, make sure the tape overhangs the side of the joist. Be sure to cover multi-ply beams and blocking entirely, and don’t forget the rim joist. Covering the rim joist will prevent moisture and rot between it and the fascia boards.

  1. For Elevated Decks, Install a Drainage System

If your deck is elevated and you have livable space underneath that you want to utilize, consider installing an under-deck drainage system. These systems completely cover the joists and act as gutters for your deck, keeping the space below dry. Just be sure you follow the manufacturer’s instructions, or water may be able to seep through the seams and still penetrate the wood framing.

  1. Install Boards Correctly and Maintain Them

This step may seem like a no-brainer, but installing your boards with the correct spacing will allow for airflow and drainage of water and debris between your boards and joists. Place your boards too tightly, and you’re inviting unwanted debris to build up in the gaps, which will lead to rot.

In addition to proper installation, regularly sweeping away dirt, debris, and leaves and washing composite boards with warm soapy water a couple of times a year will preserve the life of your deck. The same applies to wood decking, but you’ll want to go the extra mile to clean, stain, or seal your deck so the boards don’t crack, split, or rot.

In the grand scheme of your deck build, some solutions like joist tape add only a few dollars to your project but are the most effective insurance to avoid substructure rot. Go the extra mile and follow these steps to build a better deck and protect your investment for years to come.