Mason Knowles, Technical Director, SPFA Don Best, Best Roofing Systems Oklahoma City, Oklahoma Abstract SPF roofing systems have exceptional sustainability characteristics. They save ener¬ gy, are resistant to high winds, protect the substrate against damage from hail and wind driven missiles, and are renewable. However, when a SPF roof sustains damage from wind driven missiles or hail how does one determine what procedures are required to maintain the roofs long-term performance? Under what conditions can the roof be renewed? When must it be scarified, recoated or tom-off? This presentation will dis¬ cuss the type of damage likely to occur during windstorms and hail events, the affect on the SPF roofing systemi’s performance and common sense guidelines for inspecting, evaluating and recommending repairs. Mason Knowles Mason Knowles is the Technical Director of the Spray Polyurethane Foam Alliance (SPFA). He is the staff representative for SPFA’s Building Envelope Committee, Technical Committee, and Industry Promotion Committee. Knowles’ industry assignments include review of government, regulatry, and building code issues, and SPFD newsletter articles on new technology related to the SPF industry. He is a member of ASTM and chairman of D08.06 Subcommittee on Spray Polyurethane Foam Roofing Systerms. Knowles has been in the spray polyurethane foam industry for 30 years as a trade association executive, contractor, national technical representative, foam system house general manager, and spray foam equipment sales manager. He has an extensive background in SPF roofing, cold storage, industrial, commercial, and residential insualtion applications, and has written or co-authored over 30 technical papers on SPF. Don Best Don Best is the President of Best Roofing Systems, Inc. He is on the permanent faculty of RIEI, a mem¬ ber of the Spray Polyurethane Foam Alliance, of RICOWI, and has taught fluid applied roofing through¬ out the U.S. Best has a Roofing Technologist certificate from RIEI and is a professional member of RCI, serving on its Education Committee. He is currently the chairman for ASTM D08-0604 Task Group on Moisture Cured Urethane Coatings over SPF Roofing Systems. INTRODUCTION: In the words of Richard Fricklas, “SPF has an excellent story to tell when it comes to the wind and hail resis¬ tance..” The typical hail damage repair procedure for most other roofing systems is tear-off and replacement. According to Fricklas, “There seems to be a mindset among some roofing contractors as well as building owners and designers that foam roofs are not suitable for hail regions at all. ..(however,) the NRF report confirmed where (SPF) roofs had experienced hail damage the damage was localized to the upper surface of the foam and most roofs were repaired rather than replaced.” With the continued trends toward isustainable construction,” it is within the best inter¬ ests of the roofing industry to repair rather than replace whenever possible and practical. The following presentation discusses the effect of hail and high wind damage to Spray Polyurethane Foam (SPF) roofing systems and suggests common sense guidelines for inspecting, evaluating and recommending repairs. At pre¬ sent there are many industry guidelines on inspecting and repairing SPF roofing systems; however, there are at pre¬ sent, no industry guidelines that specifically address wind and hail damage to SPF roofing systems. The recommen¬ dations, descriptions and conclusions provided are the opinions of the authors and should not be considered industry standards. However, inspection, evaluation and repair techniques are consistent with SPFA’s Guideline for the Renewal of SPF Roofing Systems. 1 DAMAGE FROM WIND DRIVEN MISSILES: During high wind events a wide variety of materials can potentially impact a roof and produce damage to the coating and SPF. Rene Dupuis NRF research has indicated the damage caused by wind driven missiles typically does not cause the roof to leak. “…The unique aspect of SPF roofs with respect to mechanical damage is that they are not in imminent danger of leaking, provided the penetration does not extend all of the way through the foam.”2 Wind damage may be isolated to small areas of the roof or cover large areas. Substrate damage and structural damage may or may not occur; however, Thomas Smith noted in his observations of SPF roofs that were struck by Hurricane Andrew, “It appears a thickness of 2 inches (50mm) (of foam) is sufficient to prevent penetration of most missiles.”3 The type of repairs required will depend on the size and severity of the damage. Coating Abrasion: This condition occurs when Hurricane force winds blow sand at a velocity sufficient to erode the protective coat¬ ing over the SPF. Coating abraded SPF roofs are repaired by re-coating the affected areas. Note: If ultra violet (UV) degradation has occurred, the affected areas must be scarified and re-foamed before new coating is applied. 1 Missile Damage: Missile damage refers to cuts, gouges, dents, and abrasion to coating and SPF caused by airborne debris, such as tree branches, signs, parts of other buildings (shingles, metal panels, flashing, doors, windows, etc.), and many other non-secured items hitting the roof during a windstorm. I’ve even seen a sailboat end up on a roof. Consequently, damage from wind driven missiles is likely to be quite varied depending on the items that strike the roof. Repair small cuts (less than 3″ in the SPF diameter) by caulking the holes after the damaged SPF is removed. Repair larger damaged areas by removing damaged SPF and applying new SPF and coating to the void. 1 Hail: Damage most likely to occur to SPF roofing systems during a hail event consists of cracks, punctures and dents to the surface of the roof. Both the protective covering/coating and the SPF can be damaged. When hail strikes a SPF roof, cracks shaped like a crows foot or semi-circles may appear on the coating surface. The diameter of the cracks can be used to determine the hail stone size. The SPF, depending on the size, weight and shape of the hail, may be dented as well. The depression typically ranges from 1/8″ to 3/4″ in depth. Hail damage can be isolated to small areas or cover the whole roof. Determining short term and long-term repairs to hail damage depends on identifying the severity of the damage. It is important to note both the size and quantity of hail dents and cracks. For example, fifteen 3″ diameter hail dents on a 1000 sq. ft. roof may be less problematic than hundreds of 3/4″ diameter hail dents. Knowles and Best— 1 Sometimes, mechanical damage is not discovered for months or even years after the damage occurred. In these circumstances, repair procedures differ depending on the extent of UV degradation of exposed foam and moisture absorption of the roof. Any UV-degraded or moisture-laden SPF in the cuts, cracks/dents should be removed and caulked. If the cuts, cracks/dents are too numerous to remove and caulk, the affected areas should be scarified, refoamed and coated. INSPECTION PROCEDURES: The first step in making an evaluation and repair recommendation of a damaged SPF roofing systems starts with a thorough inspection. The following inspection procedures of an existing roofing systeml can be helpful. Visual Inspection: • Look for blisters or delaminated areas • Check the condition of the roofing system at all flashing and termination points • Look for splits or cracks in the SPF • Look for damage from impact • Check for pinholes in the SPF or coating • Check for exposed SPF and areas of eroded coating • Check for areas of ponded water • Check for obvious substrate or structural damage Physical Inspection: • Perform a non-destructive moisture survey. Follow-up suspected moisture laden areas with a moisture probe or core samples • Probe to determine SPF thickness • Take slit samples of the existing coating (at least 1 per 2500 square feet) • Take SPF samples (at least 1 per 10,000 square feet) • Take random slit samples of damaged areas Analyze Inspection: Core and slit samples should be examined for the following characteristics: • UV degradation • Presence of moisture saturation • Adhesion of SPF to substrate • Adhesion of base coat to SPF • Adhesion of top coat to base coats • Type and condition of protective coating • Thickness of protective coating • Condition of SPF • Depth of damaged SPF Knowles and Best—2 Indicate on a roof sketch the following: • Location of core and slit sample • Type and location of coating deficiencies • SPF or coating blisters • Mechanical damage • Poor drainage • Repairs required for foamstops, parapet walls, gutters, flashing, scuppers, edge terminations, expansion joints, and other perimeter items. • Repairs required to soil and vent pipes, drains, roof hatches, equipment curbs, or supports, guy wires, hot stacks, skylights, mechanical units, walkways, sleeper, pitch-pans, and other penetrations. • Water-saturated sub-roofs, insulation or SPF • Sub-roof damage or deterioration • Areas of special consideration REPAIR RECOMMENDATIONS: After you have obtained information from the roof inspection, repair recommendations can be developed specific to the damage sustained. As we discussed earlier, repairs will vary depending on the severity and the frequency of the damage. The following chart can help classify the mechanical damage and provide repair recommendations. Type of Damage Size & Severity Quantity Recommended Repair Light 1/2″ or less. Less than than 1/8″ deep 1. Less than ? cracks, cuts, and/or dents per square. 2. More than ? cracks, cuts, or dents per square 1. Coat and/or caulk dent, cuts and cracks. Recoat is optional, based on remaining service life of coating. 2. Recoat as required to fill in cracks. Light to Moderate 1/2″ – 3/4″ diameter. Less than 1/4″ deep. Less than ? cracks/dents per sq. ft. Coat/caulk cracks. Recoat as required to seal cracks. Some caulking may be required to seal deeper cracks. Moderate to Severe 3/4″ to 1-1/2″ 1/4″ to 1/2″ deep. 1. Less than ? cracks/dents per square. 2. More than ? cracks/dents per square. 1. Remove damaged SPF; caulk holes and recoat as required. 2. Scarf 1/2″ of roof surface; refoam and coat. Severe 1-1/2″ or larger. 1/2″ or deeper. 1. Less than ? cracks/dents per square. 2. More than ? cracks/dents per square. 1. Remove damaged SPF; caulk holes; recoat as required. 2. Scarf 3/4″ of roof surface; refoam and coat. Knowles and Best – 3 OTHER FACTORS TO CONSIDER: The recommendations listed above are not specific to regions or varying climates. While our recommendations remain consistent in varying climates, consequences of untreated wind and hail damage to SPF roofs vary in different climates. Hot, Arid Climates: Climates such as Phoenix or Las Vegas are very forgiving in regards to light to moderate hail damage. However, cracks in the coating can allow UV degradation over time. This degradation may take months to occur. However, this degradation typically does not affect the roof’s water resistant characteristics since the low humidity and exceptional drying characteristics of the climate does not allow the SPF to saturate over time. The main concern of light to mod¬ erate hail damage in this climate is to maintain the coatingi’s capacity for recoat/renewal. Eventually, UV degradation of the SPF under the coating will affect the adhesion of the coating to the foam. It is recommended that the damaged areas be removed and caulked or re-foamed. It should be noted there are cases of lightly hail damaged roofs in these areas being successfully recoated years after hail damage without any specific hail damage repairs occurring. Still it is prudent to make hail damage repairs as soon as practically possible. Hot, Humid Climates Climates such as South Texas and Florida have more complex factors affecting hail damaged SPF roofs. High temperatures tend to dry out the moisture that has seeped into the cracks and crushed foam cells very quickly. On the other hand, the high humidity creates a higher potential for SPF saturation particularly during cooler times of the year. Lower perm rated coatings/coverings also increase the potential for moisture saturation of the hail damaged roofs because they do not allow drying to occur as efficiently as higher perm rated products. As in the hot arid cli¬ mates, UV degradation that can affect coating adhesion typically occurs within a few months. Cool Climates: In cooler temperatures the greater concern of hail damaged roofs is moisture saturating into the SPF. There may be long periods of time where drying conditions do not occur. In many areas snow may stay on the roof for extended periods increasing the possibility of moisture saturation. It is important to repair crushed foam and coating cracks as soon as possible to prevent moisture saturation of the damaged areas. CONCLUSIONS: SPF roofing systems have unique characteristics that allow the repair rather than the replacement of the system after hail and wind damage. Hail and wind damage repairs to SPF roofing systems vary according to size, severity of damage and the length of time after the damage. It is important inspect and evaluate the damage in order to make the correct repair recommendations. However, with the correct repair, SPF roofing systems can perform for many years after a significant wind or hail event. REFERENCES: Dupuis, Rene. “A Field & Laboratory Assessment of Spray Polyurethane Foam-Based Roof Systems.” Conducted for the National Roofing Foundation, 1998.2 Fricklas, Richard. “An Update on Hail and Wind Considerations.” Presented at Spray Foam 2000, Reno, NV Smith, Thomas. “How did PUF roofs perform during Hurricane Andrew?” Professional Roofing, January 1993.3 SPFD Guideline AY122. “The Renewal of Spray Polyurethane Foam and Coating Roof Systems.” 1994 1 Knowles and Best—4
