Storm Resistant Construction

Transcription

1 Storm Resistant Construction Solutions with BASF Closed-Cell Spray Polyurethane Foam 1

2 Some Statistics By 2003, 53% of the US population lived in the 673 counties along the US coastline* On average, seven (7) hurricanes strike the US every four (4)years 40% of all Atlantic hurricanes hit Florida 83% of hurricanes Category 4 or higher have made landfall in Florida or Texas 2 *Statistics from the National Oceanic and Atmospheric Administration (NOAA)

3 Some Statistics An National Association of Home Builders Research Center study after Hurricane Andrew (1995) found severe roof damage to 77% of the homes, leading to severe water damage Surveys conducted after the 2004 and 2005 hurricane seasons revealed roof covering damage to 95% of homes with insurance claims* 3 *Statistics from Florida Bureau of Mitigation, Division of Emergency Management

4 Bottom Line A study sponsored by the Florida Department of Community Affairs found that with hurricane events, loss of roof deck and a few windows typically leads to losses greater that 50% of the insured value [of a home] * The same study concludes that Field observations and insurance claim folders indicate that the house quickly becomes a major loss once the roof deck begins to fail in a hurricane. * 4 *Source: Applied Research Associates, Inc., Development of Loss Relativities for Wind Resistive Features of Residential Structures, Florida Department of Community Affairs

5 Spray Polyurethane Foam BASF is an industry leader in polyurethane technology and applications Foams, elastomers, adhesives Raw materials Closed-cell Spray Polyurethane Foam is Seamless and conforms to any shape Self-adhering and does not sag 5

6 Technology 6 Applied to the underside of residential roof decks, SPF contributes to the performance of a sealed attic assembly, reducing the wind uplift, as well as controlling water penetration during hurricanes Closed-cell spray polyurethane foam (SPF) has the ability to enhance Performance of a sealed (cathedralized) attic assembly Resistance to air leakage Resistance to water intrusion Insulation value (thermal resistance) Structural racking strength

7 Wind Uplift Resistance The potential for wind uplift on roof sheathing in a sealed attic design may be reduced since the soffit & ridge vents are no longer allowing pressure gradient within attic.* Visscher et al (2004) showed that added attic ventilation led to more rapid destruction of scale model homes in hurricane wind-producing wind tunnels The foamed insulation on the underside of the roof deck essentially glues all the sheathing sections together, creating an additional positive effect.* 7 *Source: Florida Solar Energy Center, May 2005 Literature Review on Attic Ventilation Impacts of FL Homes

8 Wind Uplift Resistance Diagrams courtesy of Building Science Consulting From Unvented Roof Designs for All Climates 8

9 Wind Uplift Testing & Validation 9 Closed-cell SPF effects on residential wind uplift performance were recently evaluated by the University of Florida Gainesville s International Research Center Test results showed for a typical residential roof 220% performance increase (78 psf to 250 psf) with three (3) inches of closed-cell SPF uniformly applied on the entire underside of the roof deck 124% performance increase (78 psf to 175 psf) with SPF applied at the joints between the rafters and the roof deck 130 psf is the minimum design load requirement to survive 150 mph winds (Category 5) per the International Residential Code

10 Energy Efficiency & Air Tightness 10 Closed-cell SPF s unique cell structure and tenacious ability to bond to other construction materials provides an impermeable air barrier for walls, floors and ceilings Tested as a material, closed-cell SPF is 100 times less air permeable than cellulose insulation Oak Ridge National Lab study (2005) found that SPF systems significantly outperformed loose-fill fiberglass, maintaining 74-83% (low to medium density foam) of labeled R-value in cold conditions compared to 46% for fiberglass fill In addition, closed-cell SPF does not settle or degrade after installation, as is the case with other insulation materials

11 Moisture Resistance Just as significant as thermal performance and air infiltration prevention is Closed-Cell SPF s ability to help prevent water and moisture from permeating the home by creating an integral vapor retarder Fibrous insulations allow free movement of water vapor and, alone, do not serve as a vapor retarder. Closed-cell foam, when sprayed to a thickness of about 2 inches, will provide a vapor retarder of 1 perm or less, meeting IBC and IRC building code requirements for vapor retarders. Closed-cell spray foam has negligible water permeability, minimal water absorption and excellent adhesion, allowing it to act as a secondary rainwater barrier to limit damage when primary roof assembly rainwater control membranes leak. 11

12 FEMA Recognition FEMA Technical Bulletin recognizes Closed-cell SPF (and other closedcell plastic foams) as the ONLY insulation material resistant to flood damage Source: FEMA, Flood Damage-Resistant Materials Requirements, Technical Bulletin 2, August

13 Racking Strength 13 Closed-cell SPF adds strength to the building envelope through its adhesive properties NAHB racking tests have shown that foam/wood siding material can be as strong or stronger than conventional plywood panel/fiberboard sheathing construction an average of 300%! NAHB also found that special bracing for wind resistance would not be required when using SPF in the walls, which could be a major factor in reducing construction cost by allowing the replacement of 2x6s with 2x4s Alternative methods for gable wall bracing may be replaced by the use of SPF due to it s enhanced racking capacity on these walls

14 Summary: Who Gains by Using SPF 14