Task 5 Final Report - Soffit - Florida Building

1 1 of 35 Task 5 Final Report (Structural and Wind-Driven Rain Resistance of soffits ) Fiscal Year 2011/2012 Scope of Work Forrest J. Masters, Audra A. Kiesling Department of Civil and Coastal Engineering, University of Florida , Gainesville, Florida 1. DISCLAIMER Results should be considered preliminary. They are provided for the express purpose of documenting the progress made on the project during FY 2011-12. The authors anticipate releasing Final results and recommendations to the Hurricane Research Advisory Committee or Soffit Workgroup.

2 2. SCOPE OF WORK Substantial progress has been made in strengthening homes in hurricane-prone regions, such as the state of Florida . However, failure of soffits has still been seen even after these improvements were implemented. The failure of these components allows for not only change in internal pressure, but also the intrusion of occasionally substantial amounts of water. These problems looked at separately and as a combination may cause considerable damage to a residential structure. In response to the above-mentioned issues, the University of Florida was tasked to conduct both a wind resistance study as well as a wind-driven rain study of Soffit systems.

3 The task given was to: Conduct studies of structural and wind-driven rain resistance of residential soffits . Expand testing conducted in prior fiscal years on vinyl and aluminum soffits to fiber cement board, stucco/lath and other types of Soffit systems, with emphasis on overhang lengths and corner details. Findings shall be combined with fiscal year 2010-2011 results to evaluate the adequacy of Florida Building Code, TAS 100(a)-95 and to make recommendations for revisions as appropriate.

4 The contractor shall also study the air permeability / water penetration resistance of attic vent systems to develop recommendations for product performance and for evaluation and approval of vent products. The Contractor is authorized to spend up to $100,000 on Task 5. The Contractor shall provide and interim progress Report and an ending Report on this task and all sub- tasks . 3. EXECUTIVE SUMMARY This study addressed the wind load resistance, air permeability and wind-driven rain resistance of aluminum, vinyl, fiber cement board, OSB and stucco vented soffits .

5 The primary focus was the structural resistance of the panel systems because panel blow out/in is the largest source of concern for unmanaged water ingress into the attic space. A pressure loading actuator system to apply quasi-static (ramp) and dynamic wind loading derived from wind tunnel measurements to conventional Soffit systems in order to determine failure pressures. Straight and corner sections consisting of two overhang lengths (12 in and 24 in) were evaluated. The findings indicate that OSB and stucco soffits are expected to perform well over a wide range of service conditions.

6 Fiber cement board Soffit was the second best performer. The most flexible systems ( aluminum and vinyl soffits ) generally performed the worst. As expected, the 24 in overhang soffits fail at lower pressures than the 12 in counterparts. Corner sections appear to be more susceptible to wind loading than straight sections. 2 of 35 Expanded and improved guidance for installation and product approval is warranted. Our recommendations are detailed in the next section. Individual project details follow. 4. RECOMMENDATIONS Based on the findings, our recommendations are as follows: 1.

7 Establish a separate testing application standard or a section in an existing testing application standard that specifically addresses structural wind load and wind-driven rain resistance for Soffit panel systems. The rationale is twofold: a. We acknowledge that the motivation for using a universal approach ( TAS 202, 203) was to achieve a level playing field for evaluating all Building envelope products, however the lack of specific guidance for families of products is problematic particularly for Soffit panels, which differ from wall systems in that they are vented and oriented parallel to the ground.

8 B. Moreover, a review of the product approvals found that Soffit materials are qualified under multiple tests, including ASTM D5206, ASTM E330, TAS 202-95 and/or TAS 203-95. TAS 100-95(a) is also used to evaluate Soffit performance, however its applicability appears to extend only to establish water ingress requirements. Although the ASTMs and TASs establish similar requirements, allowing products to be qualified under different test procedures introduces experimental uncertainties associated variations between the test methods.

9 This issue further reinforces the need to develop specific guidelines for testing Soffit panel systems. 2. Comprehensive recommendations for creating/revising the wind load resistance evaluation procedure are provided below. Current requirements are also included, where relevant. a. Include steady and time-varying load sequences. i. Quasi-static (ramp) or staircase (step-and-hold) pressure sequences are both acceptable to recreate the steady load conditions. ii. The fatigue sequences may be taken from Tables and 1626 to achieve consistency between wall and Soffit dynamic loads, which are highly correlated.

10 We note that the fatigue sequence in Table 1626 was determined from a peer-reviewed study performed by Texas Tech University. b. Allow for the option of using high-fidelity, full-scale replication of pressure sequences obtained from wind tunnel modeling in addition to the rainflow analysis-derived fatigue sequences set forth in Tables and 1626. This approach is similar to the experimental procedure described in Sections 6 and 7. c. Require testing of both straight and corner sections.