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

Multi-Hazard Resistance


  • Emergency back-up power system
  • Easy access shut-offs
  • Emergency kit storage
  • Multiple escape exits

Flood Damage Reduction

Built above anticipated flood levels:

In non-coastal A zones, floor is 2-3 feet above BFE using one of these foundation types:

  • slab on compacted fill, extending max. 2 ft. beyond house footprint
  • slab cap on compacted fill within a stem wall foundation
  • unfinished, floodable crawl space with flood vents
  • pile, post, column or pier open foundation; enclosures vented or designed to allow entry and exit of flood water

In V zones and coastal-A zones, lowest horizontal member is above BFE with:

  • Continuous pile, open foundation
  • No or minimal obstruction as allowed by local ordinance

In areas of minimal risk (Zones C and X) near A or V zone property:

  • Lowest floor is above BFE of nearest flood zone

Additional design features:

  • Decks, porches built and anchored to resist flood forces
  • Garage above BFE or includes flood vents if below BFE
  • Garage floor, patios, etc. min. 4 in. below living floor,
  • HVAC, electrical, mechanical systems elevated above BFE

Additional flood protection features:

  • Backflow valve in sewer line
  • Flood-resistant materials and on first floor assemblies (drainable, changeable, dryable)
  • Appliance styles, installations that minimize damage in shallow floods
  • In areas protected by levees, designs and materials that are submersible, drainable and easily flushed

Hurricane and Tornado Resistance

(See wind design speed map and associated wind resistant building code for specific requirements; checklist below includes general guidelines for hurricane zones)

General Features:

  • House is < 60 ft. long
  • No more than two stories (levels)
  • Wall height of each story is < 10 ft.
  • Exterior cladding (siding, roofing, etc. rated for wind design speed)
  • Reinforced safe-room within house
  • Storm storage for outdoor items
  • Outside accessories securely anchored


For wood frame construction:

  • 2x4 studs spaced 16” o.c., or 2x6 studs spaced 24” o.c.
  • Bottom plates anchored to foundation
  • All load bearing studs anchored to bottom and top plates with metal hurricane connectors or structural sheathing with load-specific nailing pattern
  • Upper story anchored to lower story
  • Structural sheathing or inset shearwalls to meet shear load requirements
  • No windows, doors near corners
  • Corner hold-down hardware at ends of each shear wall

For masonry construction:

  • Rebar connects foundation to wall (4-ft. spacing typical)
  • Rebar reinforcement full height of walls
  • Vertical rebar reinforcement at corners and both sides of windows and doors

For SIPS, ICF and other building systems:

  • Engineered for wind speed of local wind zone

Roof, Overhangs and Attachments:

  • Wind-rated connection of roof to walls
  • Hurricane straps over every rafter/truss (preferable to clips)
  • Roof pitch between 3:12 and 12:12 (< 7:12 preferred)
  • Hip roof design (preferred)
  • Gable roof end walls braced or balloon framed
  • Overhangs < 2 ft. (or engineered, if larger)
  • Roof decking nailed to rafters with ring shank nails (not stapled) at 6” o.c. or to code
  • In tornado zone, 5/8-inch plywood roof decking
  • Roof deck seams sealed (with adhesive roof tape or membrane)
  • Min. #30 roofing felt (prefer tear resistant synthetic underlayment or peel-and-stick membrane)
  • Wind- and impact-rated roofing (Class H, UL Class 4 are best); shingles installed with dedicated starter strips, nailed per high wind instructions.
  • Attic vents protected from wind-driven rain
  • Soffits of rigid material and fastened securely to framing
  • Porch, patio, carport designed, anchored for wind load
  • Columns anchored to foundation and roof beam

Windows and Doors:

  • Height < 6’-8”
  • Meet code design pressure ratings (typically > DP 30)
  • Glass protections (plywood panels or certified impact-rated storm shutters, panels, screens, or window/door units)
  • In tornado zone, passive protection (impact rated) windows
  • Pressure rated or reinforced garage door

Fire Protection

  • Fire resistant wall cladding
  • UL Class A roofing
  • Fire resistant materials around fireplace, and in kitchen
  • Smoke alarm (combination type, battery powered)
  • Lightning rod and grounding system
  • Residential sprinkler system
  • Planned extinguisher mounting locations

Hail and Freeze Hazards

  • Hail resistant roofing (UL Class 4)
  • All plumbing in heated space or well insulated
  • Pressure relief exterior faucets
  • Pex piping (flexible)

Termite Resistance

  • No untreated wood left in soil or stored near structure
  • Moisture managed construction (See Moisture Control section)
  • Professional soil treatment under foundation
  • Termite barriers at hidden pathways
  • Best: no untreated structural wood or vulnerable insulation
  • Borate-treated wall/roof framing , cellulose insulation, foams
  • Pressure-treated (not borate) or composite wood decking
  • Masonry, concrete or steel construction

Slab foundation:

  • Monolithic poured slab
  • Slab specifications to minimize cracking
  • Steel mesh epoxied pipe collars within slab
  • Consider treatment of control joints and cracks
  • No wood forms, stakes, etc. left in ground

Raised foundations:

  • No hollow concrete blocks below grade
  • Hollow block foundation walls capped with concrete
  • Piers are solid, resistant material
  • Termite shields between foundation and framing to force termite exposure
  • Floor joists >18 in. above ground

All foundations:

  • No vulnerable foam insulation under ground (below grade)
  • Min. 8-in. clearance between siding and finished grade
  • Min. 6-in. clearance between wooden steps and soil

Foundations detailed for ease of inspection and detection

  • Porches, terraces not filled with soil
  • Porch supports separated from house min. 2 in.


  • Downspouts, sprinklers, drianlines dishcarve >2ft. from house
  • Plantings placed min. 3 feet from foundation
  • No mulch near house or only termite resistant types
  • Plumbing and conduit off the ground, no wood supports
1/30/2019 8:12:38 PM
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