Adhesives & Sealants
Tape
Trex
$15-$45/roll

Joist Tape for Deck Joist Moisture Protection

Joist tape is a self-adhesive butyl membrane applied to deck joist tops protecting them from moisture penetrating through screw holes and decking gaps. By creating a waterproof barrier this tape prevents the most common cause of deck failure: joist rot at fastener penetrations. A small investment that can double or triple deck substructure lifespan.

Key Features

  • Butyl rubber membrane
  • Self-sealing around screws
  • Prevents joist rot
  • Self-adhesive
  • UV resistant
  • Extends deck lifespan

Specifications

Widths: 1-5/8 and 3-1/8 in | Thickness: 20-35 mil | Material: butyl rubber | Self-sealing: yes around fasteners | UV exposure: 6 months | Apply: peel and stick

Best For

All deck joist tops beam caps ledger board flashing and any deck structural member exposed to water from above.

Compatible Materials

Pressure-treated lumber
Cedar
LVL beams
Steel joists
Engineered lumber
Rim joists

Pros & Cons

Pros

  • ✓ Dramatically extends joist life
  • ✓ Self-sealing around screws
  • ✓ Easy peel-and-stick
  • ✓ Prevents primary deck failure cause
  • ✓ Affordable structural insurance

Cons

  • ✗ Adds project cost
  • ✗ Must apply before decking
  • ✗ Can be slippery wet
  • ✗ Temperature sensitive adhesive
  • ✗ Some brands difficult to work with

Installation Tips

Apply to clean dry joist tops. Roll down length pressing firmly. Overlap splices 3 in minimum. Extend over beam connections. Do not stretch during application. Apply above 40F. Install decking within 6 months of tape application.

Frequently Asked Questions