How to Slate a Hip Roof

Planning

• 1

  Lay your slate on sheet metal cut in the same shape of the roof hips. To figure out the height of each course, subtract 3 inches from the length and divide by two. For example, an 18-inch slate minus 3 inches equals 15 inches. Divide that by 2 gives you 7 1/2 inches for each course. Mark story poles, strips of wood, with a wax pencil to indicate course lines. Planning your layout to account for ridges, hips and valleys will save labor in the long run, and you will make fewer mistakes.

• 2

  You will have to cut some slate while you’re laying them out. Use a slate cutter. Slowly nibble your way through the slate with short strokes. The rear of the slate will have a beveled edge. This side is the upper, slate face.

• 3

  Slate usually has holes punched in each top corner. When you cut a piece of slate and have to make holes, turn the slate over and give the smooth back two sharp raps with the point of your slate hammer. This will produce small holes on the back and larger conical holes for nails on the front.

Roof Preparation

• 4

  Build a scaffold at the eaves and wear a safety harness while working.

• 5

  Apply a strip of self-adhering bituminous membrane 1-foot wide around the edges of the roof. Install the copper or galvanized iron drip edge or flashing over this. Cover the drip edge with two 3-foot-wide sheets of bituminous membrane with 3-inch overlaps. This protects the slate from ice damming in freezing weather.

• 6

  Beginning with the bottom of the roof, use roofing nails to apply overlapping laps of bituminous felt underlayment to cover the deck.

Applying the Slate

• 7

  Nail your two story poles on the ridge at each end of the roof. Nail the ends at the eaves. Use snap lines anchored at pole marks to set your course then remove the story poles.

• 8

  Apply a layer of clear silicone caulk or elastic glue before securing each slate. Lay the slate with a 3-inch head lap beginning at the eaves. Head lap is the distance that the slate edge overlaps the nail holes of slate two courses below.

• 9

  Cover each slate with two additional layers of slate so the roof is always three slate layers deep. The nails should be twice as long as the slate is thick plus 3/4 of an inch to penetrate the deck. Drive the nails in deep enough so that the overlapping slate won’t sit on the nail head, but not so deep as to break the slate.

Valleys, Hips, Ridges

• 10

  Install valley flashing on top of the bituminous felt underlayment. The flashing should be at least 20 inches wide and have crimped edges to prevent leaks. Lay valley slates in silicon caulk on top of the flashing.

• 11

  Cut a base for the slate ridge and hip saddle caps from 2-inch-wide pieces of wood that are as thick as the three-layers of slate running up the roof. Slate saddles are two pieces of 6-inch by 12-inch slate that join together. They run 6 inches down each side of a ridge or hip.

• 12

  Cover the wood saddle base with silicone caulk or elastic glue. Begin laying saddle caps at the roof eaves and work your way up hip ridges. When you finish laying each cap, tape it into place with duct tape while the caulking or elastic glue dries.