Trampoline-Must a trampoline have a netting around it?
Seemingly, from the letter of the law, there is no requirement for a trampoline to have a netting placed around it even if it is higher than 10 Tefachim from the ground. Nonetheless, most trampolines today come with a surrounding netting as a safety feature to be extra cautious in preventing accidental falls, and while it is not obligatory, it is certainly advised. [With that said, all trampolines are viewed as potentially dangerous even if they contain a surrounding netting and account for approximately 300,000 annual injuries in children in the USA alone, some leaving permanent neurological damage, and hence the American Association of pediatrics strongly discourages their use due to risk of bruises, sprains, spinal cord damage, and bone breaks.]
 The reason: As people who go on a trampoline are conscience that they need to be careful not to fall off and that is the entire purpose of the trampoline for one to jump on it one time after the next without falling off. It is no different than going up a ladder, or climbing up a tree, were sitting on a hammock, of which in all these cases a fence of is not required to surround the person once he reaches 10 Tefachim from the ground, being that he is conscious that he must beware from falling off. This is aside for the fact that according to the Chazon Ish, a roof is only obligated to be fenced if it has living quarters under it which would automatically exempt the trampoline from requiring a fence. Indeed, the custom is not to be stringent in this matter, as even those trampolines which contain a surrounding netting as a safety feature do not fulfill the Halachic obligation of a fence being that the opening to the trampoline still remains unnetted, and whenever the obligation applies the entire roof must be fenced. One cannot make the argument that a netting is required from the letter of the law in order to diminish injury as much as possible which can come due to a person falling off, as with this argument one should from the letter of the law ban the entire use of a trampoline due to its high risk of injury even when it is fenced. With this logic, we would also have to ban bicycle riding or roller-skating due to their high risk of injury. Rather, it is clear that from the letter of the law we cannot prohibit these activities even though they do contain a certain risk of injury, and the taking of different safety precautions such as a netting is merely suggested and not obligatory.