How To Install a Faux Slate Roof

Re-roofing a house can be an overwhelming prospect. That said, there’s a lot of instant gratification in roofing, and if done on a beautiful day, it can even be (dare I say it?) fun. Whether you’re looking to save money or just have a hand in sheltering your old home, some roof projects are worth undertaking.

The finished roof is a period-appropriate accompaniment to the author’s 100-year-old Foursquare.

For me, providing the labor meant I could install a premium, historically accurate roofing product while protecting my budget. The roof of our century-old Foursquare had been replaced with three-tab asphalt shingles, but we couldn’t use the original products (asbestos shingles) to resurrect its character. Other homes of our vintage—along with many buildings in our town—were roofed with slate, a seemingly ideal compromise. But installing a genuine slate roof would mean re-framing the entire roof system to carry the weight.

The solution? Polymer roof tiles, which are both lightweight and uncannily authentic in color and look. I concentrated on the porch—as a relatively small, easily accessible section of roof, it’s a good place to try your hand at a project like this.

Step 1: Assess the Roof Condition

Before ripping off shingles, Mark takes advantage of his rooftop location to tighten up loose cables.

As with all successful projects, planning is key. Oddball items abound on old-house roofs. For instance, the existing sheathing may have been re-decked with plywood prior to the last re-roofing. It’s no big deal, unless the brackets of your original gutters are nailed directly to the original deck, which presents a problem if you need to get them out. (If this is the case, use a reciprocating saw to cut the plywood away around the brackets, remove the brackets, then re-fasten the pieces you removed using screws.)

Conversely, if the roof hasn’t been re-decked, expect rotten planks. If the roof structure underneath is open, you may need to add ¾” plywood on top of the roof deck so your nails don’t penetrate through the porch ceiling.

You also may have gutters, downspouts, or dangling wires that could use some work. Spend some time fixing these minor issues now, and you’ll thank yourself later.

Step 2: Remove Existing Shingles

The Red Ripper, capable of taking off both shingles and nails, makes easy work of stripping old roofing material.

The basic method for removing shingles is to use a “shingle shovel”—essentially, a toothed garden spade with a fulcrum that lifts shingles off the roof. Instead, I used a shingle-removal tool called the Red Ripper, which aggressively attacks both shingles and nails, allowing me to remove the shingles in heaps and also pull up nails as I go.

When you get to the final course of shingles closest to the house, cut caulk beads and remove the shingles carefully to prevent dislodging window trim, existing flashing, etc. Clean as you go—as much fun as it is to strip the shingles and heave them over the side of the porch, that doubles the cleanup time later. Instead, I stripped them into manageable heaps and bagged them on the roof, then tossed the bag to the ground. (Cordon off the area for safety first so you don’t accidentally clobber family members or passersby.)

Step 3: Install Drip-Edge and Paper

After laying 30# tar paper over the front drip-edge, Mark traps the gable end with another drip-edge, fastening it with staples.

Install the drip-edge first, nailing or stapling it directly to the front edge of the roof deck. Next, lay the tar paper. (The polymer tiles I used required 30# paper; check with your shingle manufacturer for the recommended underlayment. Roofs covering conditioned areas will also need a rubber membrane—such as Grace Ice and Water Shield—to help prevent leak damage from ice dams.)

To get the paper straight, I started on one side of the roof, laid the end of the roll flush to the outside edge of my drip-edge, and unrolled the paper a few feet. Next, I used my hammer tacker to cluster half a dozen staples in the center of the paper’s flat edge. This does two things: It holds the paper down as you unroll it, and it acts as a pivot point so you can adjust the paper slightly to keep it straight as you unroll. You can then staple off the paper as you go. The paper is lined, so overlap to the first line with your next course and repeat until you reach the top.

Cut the paper flush to the roof deck with a utility knife, then install drip-edge flush with the sidewall to trap the edges of the paper.

Step 4: Install the Shingles

Most shingles have a starter course. In my case, they were 6″ tiles set 1″ beyond the drip-edge. To ensure the starters were straight, I measured up 5″ from the drip-edge on each end of the roof, then snapped a line.

Next, I double-checked for straightness by measuring down from the sidewall to the line in a couple of spots. If the roof framing is really out of square, you’ll want to know sooner rather than later in case you need to make corrections. It’s important that each course finish parallel with the sidewall (within 1/2″ or so.)





Before you start, check the installation instructions to find out how much spacing you’ll need between tiles. My DaVinci tiles required 3⁄8″ spacing; because a starter tile is about 3⁄8″ thick, I could use one as a spacer [A] and eliminate measuring.

Snap lines up the roof such that when you lay your shingle, the top of it registers to the line [B]. The layout you choose will be determined by your tile length and desired reveal, which can vary based on product specs. I used a 7″ reveal with straight coursing, which delivers the right blend of texture and clean lines for the house.

Starting in the bottom left corner of the roof, install one set of shingles. Then work your way across the roof, completing the set. Install the next set and work across the roof again, repeating the process until you reach the sidewall [C].

For most shingles, you run the last ones in each course wild over the edge of the roof, then cut them all off at once in a straight line. With the DaVinci tiles, though, I simply adjusted the shingle widths and spacing slightly to make them fit flush with the end.

With this system, I only needed to trim the tiles [D] where they met the sidewall. A cordless circular saw with a typical construction blade worked great. And since I trapped the top 3″ or so of my final course under flashing, my last course was no smaller than half a tile, so there were no tiny pieces to mess with.

Step 5: Install Flashing

Flashing is the last step in the process, but resist the urge to rush through it to finish up the project. Proper flashing is an important detail: If it’s done wrong, you’ll have a leaky roof on your hands. For my roof retrofit, I used a custom-bent piece of flashing. I own the tool used to make the piece—a sheet metal brake—which allows me to whip up whatever I need. You can rent the tool, but you might consider subbing this job out.



Using my sheet metal brake, I bent aluminum to tuck into the house cladding and run down the sidewall and over the shingles. The last 1½” of the bottom leg is bent slightly down to channel water and to resist being blown up by wind.

Now you’re ready to lay out the flashing. On a brick home, I’d cut a slit in a mortar joint and tuck the flashing into it, but for my house, I use an angle grinder to cut the slit into the stucco wall [E], mating it up with the existing window trim for a seamless look.

The last step is to use a high-quality caulk to seal the slit [F], trapping the metal inside the masonry. I also like to dab a bit on the nail heads to ensure that my timeless new roof is ready to weather many more years.

Tags: Old-House Journal roofing slate Mark Clement Theresa Coleman OHJ August/September 2010 porches

By Mark Clement

Mark Clement is a licensed contractor and co-host of the home improvement show MyFixitUpLife. Mark and his wife work together on their hundred year old American Four Square near Philadelphia. 

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