Slate tiles are a high quality, very fragile material. They are natural stone and expensive to purchase. A slate roof has a long lifespan, and its appearance is quite beautiful. They come in a wide range of colours, sizes and thicknesses. Slate is fire resistant, which adds safety to any structure. These roofs are considered environmentally friendly because they last over 100 years. If there is less roof replacement, there is less material filling up landfills. Slate roofs vary in difficulty to install, the simpler the roof, the simpler the installation. A basic up and over roof, which is a roof with a peak and two sides, is the least difficult to install.
Calculate what is needed for the re-roofing process by measuring each side of the roof. Measure from the bottom to the peak and multiply that by the width. This is the square area of the roof. A roll of tar paper covers 2-square feet of roof. Slate tile varies in size and style but is sold by the square foot. Measure the perimeter of the roof to decide how many 10-foot pieces of drip ease metal you need. Purchase a 50-pound box of 8d galvanised nails.
Remove all old roofing to bare sheathing. Install tar paper to the entire roof surface. Always run the paper length wise from side-to-side and not from bottom to peak. Overlap the paper even with the top yellow line on the prior row run. Install nails and tin caps 4 inches apart on all seam overlaps. Nail off the rest of the paper with every nail and tin cap within 4 inches of another. Install drip ease metal around the entire perimeter of the roof. Overlap each piece 4 inches, and install a nail every 4 inches in the metal.
Apply a row of slate stone along the bottom of the roof on one side, and nail it down. Cut the last tile even with the edge of the metal. Use a wet saw or masonry blade to cut slate. Run another role of tarpaper across the roof, positioning the bottom edge of the tarpaper so it covers the nails in the slate. Install and nail down another row of slate covering the bottom edge of the paper you just laid. Make sure to offset it from the first row half the width of the tile. Cut the excess paper off that extends above the row of tile. Install that paper to cover the nails in the slate as you did with the first row. Repeat this process until the slate reaches the peak. You will have to cut the last row of slate so it does not extend past the peak. You will also have to drill holes through that row to nail it down. Put a small piece of slate under the top of each tile to keep it raised from the roof as you nail. Do not apply tar paper to the top tile. Repeat this process on the other side of the roof.
Fold the remaining cut pieces of tar paper over the peak in the shape of a triangle. Install a row of slate along the entire peak, alternating sides as you lay them. Drill through the tiles existing hole and through the slate underneath. Nail through these holes and into the sheathing. Make sure each slate tile touches the tile on the opposite side of the peak. Overlap each tile 3-inches onto the one before it. Cut the last tiles even with the roofs edge. Apply high-quality clear caulking along the centre of the peak to prevent water from getting in.