All shallow foundations in contact with clay soil will experience some degree of movement, usually seasonally, and an owner should recognize that complete isolation from the effects of clay is generally not practical or affordable. Some degree of movement is accepted by most owners, and the strategies chosen to limit that movement are a function of the owner’s sensitivity to cosmetic cracks, building use, and cost. Differential movement does not reduce the structural capacity of the foundation. The floor and foundation simply are not level. If an owner does not mind the existing condition of their house, foundation repairs are not required.
When repairs are performed, the most common method is to add pier supports under the foundation. The greatest movement is typically from seasonal shrink/swell of the clay, and it manifests at the perimeter. Stabilizing the house with added supports along the perimeter is the most cost-effective method of repair. Any pier type will work. A house is so lightly loaded that any of the commercially available systems will support the weight. The primary consideration should be depth. The added piers should be deep enough that they support the house on soil that will not be dried and wetted seasonally.
Engineers typically specify repair piers to be around 15 feet deep when trying to economically extend below the zone of seasonal moisture change. Additional depth may offer added protection against drying by large trees. The number of piers needed to reduce perimeter movement depends on the owner. An owner can choose to add supports to the areas that concern them and hope the other parts of the house continue to perform satisfactorily (partial piering) or an owner can choose to add supports around the entire perimeter all at once. Regardless, the floor can be lifted once the piers are installed, but it is highly unlikely that a contractor will be able to return the floor to level. About 1-inch of difference is normal for even a new house, and once a floor has distorted, restoring the level shape is usually impractical. (The wood framing will have essentially warped into the distorted shape.) The owner should discuss lifting, potential damage to plumbing, and any grouting of voids left under a slab by lifting it.
Finally, an owner should understand that the house still rests on clay soil and can move seasonally in the future. The piered areas will likely not settle much unless there is a severe drought that affects the deep soil, but they can still be lifted upward off the piers when the soil takes on water and heaves. For this reason, we believe it makes sense to wait until the wet season to install piers so that the house is underpinned at close to its highest level. When large trees grow close to the house, they often establish roots under it, and those roots can be cut to reduce the possibility that the interior slab will settle during dry weather, leaving the perimeter perched on piers.
Hail Yes or Hail No: Was the Metal Roof Really Damaged by Hail?
By Justin Kestner, P.E.
Disagreement over whether a roof has been damaged by hail is not a new issue. However, the past several years have seen a dramatic increase in the number of hail claims that have been filed.
From an engineering perspective, hail with sufficient mass, hardness, and impact energy can dent or rupture (tear) metal roofing materials. Haag Engineering began its ice ball impact testing program for roofing in 1963. Haag’s impact testing of metal panels in good to fair condition has demonstrated that the typical threshold size for hail necessary to rupture metal panels in good to fair condition is at least 2.5 inches. This testing involved perpendicular impacts of frozen solid ice balls—a worst-case scenario—traveling at their freefall velocities.
Hail-caused distortions along panel seams can cause openings that allow water intrusion. Hail impacts at fasteners in unsupported seams can sometimes disengage these fasteners. Ruptured panels, disengaged fasteners, and openings along seams have been considered damage to metal roofing because the water-shedding capability had been compromised. Removal of protective coatings by hail (again, typically field-applied coatings) also occurs on occasion from hail impacts and has been considered damage to metal roofing as the service life of the roof would be reduced. The question that arises in these situations is the appropriate method of repair or replacement.
Dents, dimples and dings that do not disengage panels or fasteners or disrupt protective surface coatings do not diminish the roof’s ability to shed water or reduce its expected useful service life. Yet, such conditions may be considered “damage” under certain insurance policies.
Engineers and roofing consultants are not adjusters and should remain focused in their investigations on the evidence they see at the site. Any inspection of a metal roof must focus on the basics. First, did hail fall at the site? Second, if hail fell at the site, when did it occur? Third, the size of hail that fell at the site should be documented along with the directionality of the storm(s), and if possible, a determination should be made regarding whether or not the property was impacted by multiple hailstorms. This can be accomplished by assessing spatter marks (where hail removes oxidation and grime) and dents on various surfaces including roofing materials, roof appurtenances, fencing, utility boxes, and claddings. Hail typically falls in a defined direction. Thus, one or two sides of a roof typically bear the brunt of a storm. If more than two vertical surfaces of a building are affected, this could indicate that multiple storms impacted the property. Spatter marks will fade with time and may last up to two years depending on exposure and other factors.
Engineers and roof consultants typically focus on what hail did and did not do when evaluating a property. For instance, they should note if the hail impacts dented roofing panels and to what extent. If inspecting experts find dented panels, then they should then determine whether this has adversely affected the useful life or the water shedding capability of the roof. This is accomplished by determining if impacts caused panel ruptures, disengaged fasteners, or caused openings along panel seams. If there is evidence of hail-caused openings, the expert may be asked to determine if this has caused any interior water damage. Further examination may include searching for dented roof appurtenances; dented or fractured siding and/or window trim; broken windows; dented gutters and downspouts; dented overhead or man doors; etc. Other considerations include separating mechanically-caused conditions from hail impacts. For example, dents with scratches in them are indicative of mechanical impact rather than hail impact, as hail is not hard enough to scratch metal. Further, disproportionately large and/or deep dents relative to the size of hail that fell in the area may be indicative of foot traffic or some other cause rather than hail.
Engineers and roof consultants are hired to document their observations and render opinions based on their expertise. They do not make coverage decisions because that is always the role of the insurance claims professional. As a result, it is critically important that the claims professional consult with the engineer or roof consultant at the early stage of the claim, so that the expert’s report provides sufficient information for the claims professional to make the proper decisions based upon what is considered “damage” in the applicable insurance policy. This is where having a clearly defined scope of work can benefit both parties.
Once damage is determined to exist, reparability of metal roofs can be a complex issue and may require estimates from construction consultants or roofing contractors. Questions sometimes arise regarding whether or not dents have adversely strained the metal. If a dispute lingers over this issue, dented samples of the roof could be removed by a qualified roofer and inspected by a qualified engineer or laboratory professional.
Dating the approximate time frame of a storm can also be important. In this situation, the engineer should check weather records and inspect the roof for spatter marks coincident with dents to determine if the dents were from a recent storm. Weather service reports by third parties are another tool that can be utilized. An engineer should always look at the weather service reports in conjunction with what can be supported and documented by site conditions.
This is excerpted from “Testing Your Mettle”, which originally appeared in The CLM. The article was co-authored by Kevin Kennedy, esquire. The full article can be found by clicking here.
Justin Kestner, P.E. President and CEO, Haag Engineering
Justin Kestner graduated from Villanova University with a Bachelor of Science degree in Civil Engineering. He earned a Master of Science degree from Lehigh University in Civil Engineerning, where he focused on structural engineering. Mr. Kestner also has a Master of Business Administration degree from Villanova. He is licensed as a professional engineer in 17 states. Mr. Kestner currently serves as the President and CEO of Haag Engineering, as well as a Principal Engineer. He is a member of the American Society of Civil Engineers, Phi Kappa Phi National Honor Society, the loss Executives Association, the National Council of Examiners for Engineering and Surveying, and the Fritz Engineering Research Society. Mr. Kestner has been with Haag Engineering since January 2006. See his profile here.