""When you build a new house, you shall put a fence around your roof, and you shall not put blood in your house if anyone falls from it." (Deuteronomy 28:8)
Throughout history, roofs were used for storage, drying grain, or simply resting. They were also dangerous. The Torah commands us to minimize this danger by building a fence at least 10 fists high (tefachim) and strong enough to support the weight of an adult. Roofs that are not in use (for example, a steeply pitched roof) do not need to be fenced.
This rule extends beyond roofs and applies to any hazardous situation. Examples include balconies and staircases, and holes in a building must be covered or fenced off. Swimming pools must also be protected.
Ideally, one should not own a dangerous dog. A dog is considered dangerous if it frightens people.
It is also forbidden to endanger oneself. Some examples include wading through fast-flowing water deeper than waist-deep and driving a vehicle at a dangerous speed.
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