Presentation on theme: "New Approaches to Minimizing Water Intrusion in Attics Coastal Contractor Summit May 12-14, 2008 Tim Reinhold Director of Engineering & VP Institute for."— Presentation transcript:
New Approaches to Minimizing Water Intrusion in Attics Coastal Contractor Summit May 12-14, 2008 Tim Reinhold Director of Engineering & VP Institute for Business & Home Safety
IBHS Mission To reduce the social and economic effects of natural disasters and other property losses by conducting research and advocating improved construction, maintenance and preparation practices.
Performance of New Building Code Buildings 3
Strong Codes Reduce Claim Severity and Frequency (Preliminary Results) Severity Pre 1996: $24/sf : $14/sf - 42% Frequency Pre 1996: 41 claims/100 policies : 17 claims/100 policies - 60% 4
Amount of Roof Damage * Includes claims with known damage types only, except for partial covering/partial decking. 5
Interior Damage and ALE by Year of Construction 6
Causes of Failure and Problems Building Envelope Issues Structural Issues
Building Envelope Issues in Priority Order Loss of roof covering Loss of roof sheathing Debris impact - broken windows and doors Window and door framing and anchorage Garage doors Ridge vents, off ridge vents, gable end vents and soffits Water leakage – windows, doors, siding, etc.
Shingle Roof Observations Many Older Roofs suffered extensive shingle damage Roof covering damage frequently resulted in significant damage to interior Newer wind-rated shingles installed to manufacturers recommendations performed well How much is due to being new and how much due to product improvements?
Roof Coverings - Tile Signs of damage propagation Success stories were there in Charley
Tile Roof Permit Study (10,375) County & City Population
County & City Tile Roof PermitsPost Charley Replacement
Tile Roof Observations Tile roofs have better secondary water protection When roofs failed, few tile roof owners had as much water intrusion through deck as shingle roof owners Some roof vent problems where vents failed and acted as scoops Relatively light damage in lower winds Tile failures produced large financial losses Large deductibles Source of significant debris damage
Florida 2004: A Tale of Two Coasts On East Coast after Frances and Jeanne, Palm Beach Post Very critical of shingle roofs Very supportive of tile roofs In Punta Gorda and Charlotte County Many homeowners concerned about tiles Numerous positive comments about the performance of new metal roofs Local covenants requiring tile roofs
Tile Look Metal Roofs
Standing Seam Metal
Metal Anchorage near edges is key Sheathing or deck is important Provide secondary water protection – upgraded underlayment
Metal Roof Observations Certain new installations performed very well 5V Crimp seemed among best Easy to inspect screw spacing Installed over decking Standing seam exhibited mixed results Sometimes no deck under panels More difficult to inspect clip spacing on deck applications Systems that include a separate deck offer opportunity for secondary water protection Degradation with ageing and fatigue?
Secondary Water Protection Goal is to dramatically reduce the amount of water that pours into the attic through gaps between roof sheathing when the primary roof cover is blown off.
Underlayment as Secondary Water Protection Fully adhered membrane covering
Underlayment as secondary Water Protection Mechanically attached membrane
Table 3-4 Horizontal Overlap of "High Performance" Underlayment Sheets to Avoid Sealing Edges ASCE 7Fortified Roof Pitch XX on 12 Design 5:126:127:128:1210:1212:1214:1216:1218:12 Wind Speed Required Overlap for "High Performance" Underlayment to Avoid Sealing Edges mph inches NA NA NA NA NA NA = Not Allowed - overlap is greater than 19-inches.
Secondary Water Protection Using Self Adhering Strips Self Adhering Modified Bitumen products Ice & Water shield Available in a Variety of Widths Most Economical in 6” widths
Closed Cell Urethane Based Adhesive Foam Sprayed on Joints
Tearing Around Fasteners
Roof Deck Failure
Roof Deck and Gable End Failures
Loss of Roof Sheathing & Gable End Failure
Key Elements for Roof Sheathing Attachment fastener size and type fastener spacing – particularly in the field of sheathing (These two items have the greatest effect on uplift resistance) Spacing of support members Sheathing thickness (head pull-through); fatigue around fasteners
Sheathing Uplift Resistance Uplift capacity is best correlated with tributary areas of fasteners Depends on missing fasteners Depends on head pull-through for thin sheathing ( < 5/8”) For 1/2” or thinner sheathing - can be reduced based on nail head shape For 1/2” or thinner sheathing - can be reduced by over-driven fasteners For screws, capacity can be limited by head pull-through even for 5/8” sheathing
2 sq. ft. 1 ft. 2 ft. 1 ft. ½ ft. ½ sq. ft. Ratio of Tributary Areas = 4 to 1 6 and 12 spacing of fasteners 41
1 sq. ft. 1/2 ft. 2 ft. 1 ft. ½ ft. ½ sq. ft. Ratio of Tributary Areas = 2 to 1 6 and 6 spacing of fasteners 42
Roof Ventilation as a Source of Water Intrusion Soffits Gable rake vents Gable end vents Ridge vents Off-ridge vents TAS 100(A) type tests are all that are currently available to try and evaluate some of these products
Soffit Failures 75% of Homes with claims
Failure Due to Poor Installation – Lack of Test Standards – Not Following Product Approvals
Major Code Change Soffits to be designed to withstand the same pressure as the adjacent wall Dead-wood and following manufacturer’s installation procedures is important Retrofit solutions indicate issues
Retrofitting Vinyl and Aluminum Soffits Anchorage of soffit to wall Bead of adhesive Screws through channel and soffit material Anchorage of soffit to fascia board Adhesive in notches Screws through fascia flashing and soffit material Improved anchorage of flashing Removal and installation per manufacturer’s high-wind installation recommendations
Gable End Vents
Gable End Rake Vents
Off Ridge Vents
Nails holding off-ridge vent in place
Off Ridge Vent Failure
The Bad News about Code Provisions Roof coverings are still a major problem area (95+% of homes with claims had roof covering damage) No good test procedure for soffits and water intrusion through soffits (75% of homes with claims had soffit damage)
The Really Bad News Many coastal areas are not using modern engineering based standards for housing construction The migration of people to the coasts is expected to continue Values of coastal properties are continuing to escalate We are in a cycle of increasing frequency of events Demand Surge- cost of material spike Climate change – NOAA 90%+ confidence = higher wind speeds in hurricanes
What About Sealed Attics? Improved energy efficiency Get rid of attic vents all together Depending on type of insulation – can provide additional protection from water intrusion Use of Air Admittance Valves – could just about eliminate roof penetrations.
Air Admittance Valves
Why not think about…
Code Plus Construction Options
Beyond Building Codes Increases design loads for pertinent hazards Performance based criteria with some prescriptive options Paying attention to water penetration Wind and/or hail impact resistant roofing Formal design review Connections, connections, connections Verification through targeted inspections Some limited insurance discounts are available