This is broader than the coverage provided on either the CP 10 10 or the CP 10 20 because coverage is triggered when an opening is made by any covered cause of loss rather than being restricted only to damage done by wind or hail.

The unendorsed HO-3 provides specific perils coverage for Coverage C, Personal Property. The windstorm or hail peril excludes coverage for damage to personal property located within a building caused by rain, snow, sleet, sand, or dust unless the direct force of wind or hail damages the building causing an opening in a roof or wall, and the rain, snow, sleet, sand, or dust enters through this opening.

A subject of considerable litigation in the courts has been the question of what is direct physical loss caused by or resulting from windstorm. Forms do not define "windstorm" and so the courts are often asked to do so  within the circumstances of a particular case. The great majority of courts agree that the wind does not need to be the only cause of loss for there to be a loss directly related to windstorm; the rule is that the windstorm must be the proximate cause or the efficient proximate cause of the loss. The minority of courts have followed the rule that any contributing cause to the damage must itself not be excluded by the policy.

Many courts have followed the rule that a direct loss from windstorm is established when it is shown that the force or strength of the wind caused the damage. Some jurisdictions require that the winds be tumultuous and have the nature of a storm.

Some courts have addressed the issue of whether there is direct loss from windstorm when the property that was damaged was in poor physical condition, generally finding that there is such a loss if the windstorm was the proximate cause of the loss.

Coverage questions have been complicated for several years by the doctrine of concurrent causation. Under this doctrine, open perils property policies were held to cover losses caused jointly by an excluded peril, such as flooding or earth movement, and some other peril, such as windstorm, not excluded by the policy. Some courts, most notably the California Supreme Court, are returning to the more traditional property insurance concept that allows coverage only when the nonexcluded peril is the proximate or efficient proximate cause of the loss.

One Florida court explained the difference between concurrent causation and efficient proximate cause as follows:

The concurrent cause doctrine and the efficient proximate doctrine are not mutually exclusive. Rather, they apply to distinct factual situations. The concurrent cause doctrine applies when multiple causes are independent. The efficient proximate cause doctrine applies when the perils are dependent. Causes are independent when they are unrelated such as an earthquake and a lightning strike, or a windstorm and wood rot. Causes are dependent when one peril instigates or sets in motion the other, such as an earthquake  which breaks a gas main that starts a fire."

See Paulucci v. Liberty Mut. Fire Ins. Co., 190 F. Supp.2d 1312 (M.D. Fla. 2002).

Review of Court Decisions

In Koory v. Western Cas. & Sur. Co., 737 P.2d 388 (Ariz. 1987), the Arizona Supreme Court held that in order for an insured to recover for a windstorm loss, it was not required that wind be the sole or unaided cause of the collapse of a warehouse roof. The insured's warehouse was severely damaged when the roof collapsed during a storm; besides wind, other factors such as the weight of pooled water and the roof's age and condition also contributed to the loss. The insurer had relied on an Arizona appellate decision stating that windstorm insurance covers a loss only if the damage to the insured property is caused solely by the unaided force of the wind and the insured property is in reasonable condition. The court, noting that the trial court's granting of judgment to the insurer without trial was inappropriate, sent the case back for trial.

Before sending the case back for trial, the court stated that the real issue was what constitutes a windstorm since the policy left the term undefined and did not insure every loss caused by wind. The court asserted that the insurance company had misconstrued the earlier appellate decision, and stated that the "unaided action" and "reasonable condition" requirements were terms of measurements and not exclusions used to limit coverage for windstorm. Thus, a windstorm must be a wind of sufficient force to damage the insured property either by its own unaided action or by projecting some object against it. Further, the reasonable condition requirement was not whether the property was in objectively reasonable condition, but whether the property was in reasonable condition when compared to its condition at the time it was insured (in order to uphold the expectations of both parties). The court stated that "when an insurer agrees to insure a building against windstorm damage, the insured may assume it intended to insure the building in its current condition, even if the building is in objectively unreasonable condition."

Thus, the court concluded that where the policy contains no requirements for structural integrity or inspections before windstorm coverage will be issued, "a windstorm is a wind of sufficient force to proximately cause damage to the 'ordinary condition of the thing insured.'"

In Shinrone v. Ins. Co. of North America, 570 F.2d 715 (8th Cir. 1978), the court held that the insureds were covered for windstorm loss because it was the proximate cause of the death of their livestock. The policy stated the following concerning the coverage of the livestock: "This policy insures livestock against: (1) death or destruction, directly resulting from or made necessary by: … (b) windstorm…This policy does not insure: … (b) against loss or damage caused by…dampness of atmosphere or extremes of temperature."

During a severe wind and snow storm, 166 calves on the Shinrone ranch died. Before the storm, the weather had been very warm and wet, causing the feed lots on the ranch to be mired in two feet of mud by the time the storm began. The insured's veterinarian testified that six factors combined to cause the animals  deaths: (1) wind; (2) drop in temperature; (3) snow; (4) the size and age of the cattle; (5) the extremely muddy conditions; and (6) the lack of adequate wind protection. He testified that the wind was the most important factor in the deaths, but that the wind alone would not have killed the animals.

The trial court's instruction to the jury on the question of whether the deaths were directly caused by windstorm allowed recovery where the windstorm was "the dominant or proximate cause" of the loss. The appeals court, referring to the insurer's position on the interpretation of direct loss by windstorm, stated that "we feel that [the insurer's] restrictive view of its coverage, requiring a windstorm 'with little or no precipitation  and of 'sufficient violence to be capable of damage to the insured property by its own unaided action,  renders the policy virtually inoperative and practically meaningless. No coverage would exist during the winter months and the highly restrictive coverage during the other months would be of such limited value as to be an imposition on the public seeking insurance covering losses occasioned by the vagaries of the elements." Since the jury had determined that the windstorm was the dominant or efficient cause of loss, there was coverage even though other causes may have contributed to the loss.

The Mississippi Supreme Court held that the insured's loss was totally covered in Grain Dealers Mut. Ins. Co. v. Belk, 269 So. 2d 637 (Miss. 1972). During a hurricane tree limbs damaged the insureds roof, causing a leak. The insured hired a tree cutter to remove the tree, and the tree broke and fell on the house while being removed, causing more damage. The court found that the insured had not failed to use all reasonable means to preserve the property. However, an insured must present credible evidence that he acted to preserve the property when the loss occurred, as held in Crownover v. National Farmers Union Property & Cas. Co., 673 P.2d 1301 (N.M 1983).

The court in Couri v. Home Ins. Co., 368 N.E.2d 1029 (Ill. App. 1977) followed the rule that direct loss by wind is established when the insured shows that the force or strength of the wind caused the damage. The insured owned a nightclub that was damaged when a tree and other debris struck the building. The court determined that there had been sufficient evidence for the jury to conclude that the damage was a direct loss by windstorm. There was no eyewitness testimony and a meteorological technician with the National Weather Service stated that the highest wind speed recorded on the date of loss was twenty-eight miles per hour, a wind strong enough to break small limbs from trees.

However, the court found that circumstantial evidence was strong enough to find for the insured. The tree had been completely uprooted and moved a distance of approximately forty feet. There was no other reasonable explanation for the damage, and there was evidence of sixty-three mile per hour winds on the day before the loss, and fifty-six mile per hour winds on the day after.

Finally, the amount of time between the windstorm and the resulting loss is not conclusive as to the directness of the result, the court said in Peerless Hosiery Co. v. Northern Ins. Co., 108 F. Supp. 52 (D.C. Conn. 1952). More than half of the insured's roof was blown off by a hurricane. Twelve days later a rainstorm caused damage to his merchandise when it entered through the tarpaulins placed over the openings in the roof. The court refused to find that the loss to the merchandise was indirect simply because of the lapse of time. The court stated, "[I]n the law of insurance … the amount of time elapsing between cause and result is not necessarily conclusive as to the proximateness or directness of the result." The roof had been repaired with reasonable speed because roofers were in high demand after the storm. But the court held for the insurers because it found that the insured did not comply with a policy requirement to preserve property from further damage; the insured had moved the merchandise to an undamaged part of the building but had not covered it with tarpaulins.