A release from or waiver of liability should protect you from the normal risks to the people doing the work: e.g. if the gutter cleaner falls off his ladder, since that is normal risk attendent upon work like that. It will not protect you from:1) "abnormal" risk caused by dangerous conditions at your home (if any)--for example, if you have a crumbling stoop or stair which you have not fixed, and a contractor, etc. falls because of it;2) claims by third parties who did not sign the waiver or release--like if the gutter cleaner falls off his ladder onto a neighbor. (In (2), you probably should not be liable in any event, unless something you did caused or contributed to the accident, but it's highly likely you'd be included in a lawsuit and at least have to respond to it. The waiver will not preclude a lawsuit, since it does not bind anyone who did not sign it.)You can make sure you only employ contractors who provide proof they have their own insurance to protect them, you (if they injure you or damage your home) and others--that will increase your protection.