How far back should tree limbs over a roof be cut?
At least 6 feet from the house, say NC State Extension and the NC Wildlife Resources Commission, both writing about squirrels reaching the roof. The same Extension handbook says squirrels "can jump 6 to 8 feet laterally," so 6 feet is a floor, not a squirrel-proof line.
Six feet is a squirrel distance, and squirrels can jump farther
NC State Extension's Gardener Handbook calls for trimming limbs "at least 6 feet from homes and buildings" to reduce squirrel access, and the NC Wildlife Resources Commission says to trim them back at least 6 feet "to prevent squirrels from jumping from a tree to your roof."
The same handbook says squirrels "can jump 6 to 8 feet laterally," so 6 feet is a minimum, not a gap no squirrel can cross.
Each cut goes to a side branch or to the collar
NC State Extension's pruning guide shortens a branch with a reduction cut, back to a side branch large enough to take over, and that cut leaves no stub. A limb that comes off entirely goes "back to the collar," the often slightly swollen tissue where it joins the trunk or a larger branch. The distance picks the limbs; the tree's branching picks each cut.
Six feet is not a clearance from the wire
Six feet is a squirrel measure, not a clearance from the line to the house. A limb on or near that wire waits for the utility; limbs on the roof or the line to the house gives the reasons, and what drives a tree trimming quote spells out the utilities' service-line rules.
Arbor Aves Tree & Crane's tree trimming and pruning, one of its five services, includes cutting limbs back from roofs.
How close do the limbs come, and over which part of the roof?
Questions people actually ask.
Why not cut each limb off where it crosses the roof line?
A cut at the roof line usually leaves a stub. The USDA Forest Service's "How to Prune Trees" says stub cuts "delay wound closure and can provide entry to canker fungi," and NC State Extension advises against leaving one.
Will a limb cut back from the roof grow right back?
Cut between buds, a limb sprouts or dies back. The USDA Forest Service's guide says cutting side branches between nodes ends in "the development of epicormic sprouts, or in the death of the cut branch back to the next lateral branch below," and those sprouts, shoots from latent buds, "are weakly attached to the stem." NC State Extension says a properly reduced plant "will not grow back as vigorously as when headed back."
Is cutting limbs back from a roof the same as topping?
No. NC State Extension calls heading large branches or trunks "topping or stubbing" and "an inappropriate pruning practice," while a reduction cut leaves no stub.
Does the 6-foot figure count for every tree near the house?
Yes: the sources name limbs, not a particular tree. The NC Wildlife Resources Commission's squirrel sheet adds that metal collars on the trunks of trees near homes fail when nearby canopies are within a squirrel's jump, so the nearest limb counts.