What Crown Raising Is and Is Not
Crown raising removes the lowest limbs so that people and vehicles pass underneath without contact. It is not thinning, which takes wood out of the interior, and it is not topping, which shortens the leader. The whole operation happens at the bottom of the canopy, and the measurement that matters is the height of the lowest living wood at its lowest point, usually a drooping tip rather than the attachment.
Height Over a Driveway
Over a driveway the working number is around fourteen feet, because that clears a moving van, a boom truck and most travel trailers. Branches sag when they are wet and sag further when loaded with acorns, so the clearance you cut on a dry day is not the clearance you have during a downpour. Cut to fourteen feet in dry weather and you keep roughly twelve when it rains hard.
Height Over a Sidewalk or Front Walk
Over a public walk or a front path, eight feet is the common target, enough for a tall adult carrying something on a shoulder. Water oak and post oak both send low limbs out nearly horizontally, and those are the ones that catch. On a corner lot the sidewalk runs along two frontages, so the raise has to be done on both sides of the tree, not only the side facing the house.
Corners, Stop Signs and Sightlines
At a street corner the issue is what a driver can see, not what fits underneath. Foliage between roughly three and eight feet above the pavement sits exactly in the window where an approaching car, a cyclist or a child appears. Clearing that band on both legs of the intersection matters more than total canopy height, and it applies to shrubs and low sweetgum growth as much as to mature limbs.
Lifting Without Ruining the Tree
A tree lifted too far looks like a lollipop and behaves like one, because the lower limbs are what taper the trunk and steady it. Keep live canopy on at least the top two thirds of the stem, and spread the raise over two or three visits instead of one. Pines tolerate a hard lift because they shed low branches anyway; post oak does not, and a stripped post oak trunk will sunscald.