Weatherizing deck joists is a crucial step to ensure the longevity and durability of deck structures, especially with the shift toward composite decking, which can often outlast its wooden supports. Properly protecting these structural components from moisture damage can prolong their life significantly. This guide provides step-by-step instructions on how to weatherize your deck joists using techniques with HydroFlash UV+.

Why Weatherize Deck Joists?

With the rise of composite decking, which can last much longer than traditional wood, it becomes even more critical to protect the wooden supports that remain prone to moisture damage. Water can accumulate on the tops of these joists and beams, leading to absorption and eventual decay. By weatherizing these vulnerable points, you can significantly extend the lifespan of your deck’s structural framework.

Benefits of using HydroFlash® UV+ for Deck Joists

HydroFlash UV+ high-performance flashing tape offers several advantages over traditional deck joist tapes or other flashing tapes available on the market:

  • HydroFlash UV+ is black, making it visually discreet when looking through the gaps in deck planks.
  • It is UV stable, ensuring durability against minimal UV exposure.
  • It is vapor permeable, which allows moisture absorbed by the joists/beams to evaporate, helping to prevent long-term damage.
  • It is available in multiple widths (2.3”, 4”, 6”, and 9”), ensuring full coverage and protection for various joist sizes.
  • HydroFlash UV+ self-seals around fasteners, providing an additional layer of protection during deck board installation.

Steps for Installing HydroFlash® UV+ on Deck Joists

  • Step 1: Ensure the joists are clean and dry before application.
  • Step 2: Unroll HydroFlash UV+ and position it over the joist.
  • Step 3: Apply pressure to activate and integrate the acrylic adhesive. This step is crucial for ensuring a secure bond.
  • Step 4: For wider joists and beams, use a tape width that allows for full surface coverage with some overlap, ensuring a shingle-like effect that directs water away from the wood.
  • Step 5: Continue this process for all joists before installing the deck boards.

HydroFlash UV+ Samples


Importance of Proper Ventilation

Proper ventilation is critical for allowing the deck joists to dry out after wetting events, preventing moisture accumulation and structural degradation. Most decks allow for air circulation since they’re built outside, which helps maintain the integrity of the wood. Ensuring there is adequate space between the deck boards and that the underside of the deck is open to airflow can further enhance ventilation.

Tips for Long-Term Performance and Longevity

Follow these four tips for when you’re weatherizing deck joists:

  • Invest in high-quality materials like HydroFlash UV+ for superior protection.
  • Ensure the tape is firmly pressed onto the joists to activate the adhesive properly.
  • For stair stringers and steps made from wood or pressure-treated wood, protect the exposed v-notched areas to prevent moisture absorption.
  • Always aim for best practices rather than just meeting minimum code requirements to ensure maximum durability.

Weatherizing your deck joists helps protect your customers’ investment and durability of the deck. Using products like HydroFlash UV+ can provide superior protection against moisture, UV exposure, and physical damage, ensuring decks remain safe and functional for years to come. Order a sample today or find where to buy!