Checklist for Decay Resistance

Decay Resistance

Moisture Control

Architectural detailing that sheds rainwater away from walls:

  • Overhangs all around (2 ft. wide)
  • Roof pitch between 3:12 and 6:12
  • Roof drip edge
  • If lacking overhangs, non-clogging gutters or diffusers
  • Covered entries
  • Cap flashing with drip edges above windows, doors
  • Extended, sloped window sills
  • Sloped porches, balconies, driveways, etc.

Roof leak reduction:

  • Simple roof design
  • No flat roofs
  • Minimal penetrations; leak-resistant vent systems
  • Properly installed flashing at penetrations, valleys
  • Step and kick-out flashings if a roof intersects a wall
  • Higher performance underlayment for leak-prone roofing types

Continuous drainage plane in walls exposed to rain:

  • Drainage space behind cladding in high rainfall areas
  • Vented space behind cladding in extreme rainfall areas
  • Or, sealed masonry construction (reservoir system)
  • Flashing of windows, doors, etc. that continues drainage plane
  • Shingle fashion installation of all materials
  • Flexible flashing tape, waterproof coating or sill pans and corner guards
  • Doors set in pan flashing or “seat” in slab

Hot, humid climate ideal wall assembly (zones 1A, 2A, lower part of 3A):

  • Air flow retarder to the exterior
  • Vapor diffusion retarder to the exterior
  • Permeable interior finish (no vinyl wallpaper)
  • Unfaced cavity insulation

Mixed, humid climate ideal wall assembly (zones 4A, top part of 3A):

  • Air flow retarder to the interior
  • Permeable interior finish (no vinyl wallpaper)
  • Vapor diffusion retarder that adapts to seasons:
  • > R 5 insulating rigid foam sheathing
  • Kraft paper faced insulation
  • Special membrane that is low-perm in winter and high-perm in summer.

Water managed foundation:

  • Ground slopes away from foundation
  • Gasket between foundation and framing

For slab on grade house:

  • Durable plastic sheeting under slab and lining the grade beam
  • Coarse gravel drainage bed under slab

For raised house:

  • Ground level under house higher than outside grade
  • Plastic ground cover in enclosed crawl space
  • Entire wood subfloor treated to resist decay
  • Drainage board for any below grade walls
  • Insulation system that minimizes condensation on wood framing


  • Exhaust fans, clothes dryer do not vent under house or into attic
  • Wood, fiber cement siding backprimed
  • No plumbing within exterior walls
  • Stainless steel hoses for clothes washer
  • Sloped floor and drain or drain pan for clothes washer, water heater
  • Air infiltration control (see Energy-efficiency section)
  • Humidity control system (see Healthy/ Indoor Air section)

Long-Lasting Materials and Equipment

  • > 40-year roofing warranty, 12 year total-system 100% warranty
  • > 50-year cladding warranty or masonry
  • > 10-year window frame, 20 year glass warranty
  • pressure-treated wood, masonry, steel structural components
  • fiber cement, composite or other long-life trim
  • plastic lumber or pressure-treated wood decking
  • appliances, equipment with longer warranties
  • long-lasting floorings
  • foundation designed for soil conditions
1/30/2019 8:43:20 PM
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