Soooooo… the shingles over my garage have been telling me for years that I need to get a new roof. When it became apparent just how scrappy they were becoming, I tried to add a downspout tube from the top egress to the garage eavestrough/downspout, so that at least the water would stay contained, but no dice; I needed a good crimp tool and cutter to make it fit. The new downspout pipe floated off the roof one rain, right onto the driveway. Bummer.

This wasn’t the first time I had to reshingle the roof; back when I bought the house, the seller’s notes stated the roof was due. I did it not the first spring, but the following. It was the biggest expense I’d ever paid at that point. I even had to spring an extra $20 (or maybe it was $40) for them to roll the little plastic leaf-exclusion nets over the eavestroughs (a rip-off, both the cursory labour needed and the devices, which the squirrels ripped down in less than a minute). But at least the roof was done, with 25-year shingles, which really means 20.

Exploring the idea of a green roof

A half dozen years after that – say, around 2014 – I learned about green roofs and thought “shoot, I would have liked to have done that.” And in 2023, when it was clear that the roof was due for renewal (now 15 years old, and looking like it did above), I began researching green roofs. I just loved the idea of having one of a variable, almost-rocky-beach substrate held in place by sedums and other fen-like or grassy plants.

To whet my imagination to the project, I picked up a literal stack of library books from the BANQ to come up with a plan and maybe even cost it out to do in 2024 or 2025. The books proved fertile not just for a flat-roofed structures, like people are (still only) beginning to adopt as green, but also for sloped structures in different kinds of environments.

Here’s a shortlist of the books I read, with the BANQ (and other libraries) call numbers being around 635.9671, all on the same shelf.

Essential Green Roof Construction – Leslie Doyle, © 2021 – well worth the reasonable cost, if you’re seriously undertaking such a project in Canada, and maybe elsewhere as well.

The Professional Design Guide to Green Roofs – Karla Daken, Lisa Lee Benjamin, & Mindy Pantiel. Definitely an inspiring and informative book about projects around the world, if you’re playing with ideas of what you could do

Small Green Roofs – Nigel Dunnett, Dusty Gedge, John Little, & Edmund C . Snodgrass. Creative and practical for alternative projects; this is a book I will return to for my country house or a creative shed

And for the botanists: Green Roof Plants, by Snodgrass & Snodgrass. How to lay a substrate (well, all books do this) and a long list of plants to choose from.


Then came the measuring. Forgetting I had blueprints to the house, I had it on my to-do list to measure the ‘a’ and the ‘b’ of the ‘c’ that was the length of the slope of my garage roof (the hypotenuse), to find out the angle of the slope. This task had to happen anywhere from late fall to mid-spring, before the vines leafed out and obscured the horizontal brick-line from the point of the eaves.

But then I found the blueprints, and read that the rise-over-run of the garage roof slope was 5′ over 12′, with the top roof’s being 4′ over 12′. In both cases, this ended up in an angle that was too steep for an inclined green roof. I inquired with Toits Vertige about this project, and they informed me the maximum slope for a green roof would be 17%, which translates to 15º. So that meant my “green roof over the garage” dream was dead for this house. (Some future home or shed, maybe!)

The next best option in green roof engineering

I had three options left open, and one of them was unsuitable and probably prohibitively expensive for me: a slate roof. Now, if your roof has the engineering and your building the design to support slate, go for it! And if your roof is already slate, please don’t convert it. It’s got such heritage value, it would probably not be permitted by the city if you tried.

And permitting might limit my options, as well. I’m in a row of houses with standard felt-backed asphalt shingles. Up until a few years ago, all the shingles matched, but since then one house converted to grey, and another a darker brown. All the old colours are still available in both felt-backed and the newer fibreglass shingles. Both are recyclable, if your facility will do so, but it typically requires an industrial grinder and a separator to pull out the roofing nails, because the roofers will not do that themselves. The new fibreglass asphalt shingles are actually even more recyclable than the old ones (and the shingles are a lighter load, too) but again, only if the facility has the capacity to do so. Most roofers just take them to the landfill.

The third option was metal: various styles, infinitely recyclable, and of a much longer life than asphalt shingles (40–70 years is the range).

Permit required

As part of the process of getting the permit to re-clad my roof (this wasn’t required the first time I did it!), I called several roofing companies to get quotes for metal roofs and fibreglass-asphalt. Though the price for a metal roof was triple the estimate for the asphalt shingles, the life of the roof, other benefits1, and the curb appeal factored into it. What my permit would allow would determine which choice I would make.

I met with the borough permit officer. That my row house maintained a harmonious look with its neighbours was important, so the corrugated metal roof option I’d enlisted was disqualified. The flat, interlocking metal shingles named Wakefield Bridge (if you’ve been to Wakefield, Quebec, you’d know what they’re named after!) were still in the running.

The borough also wanted the lightest material colour choice I would find acceptable. Obviously, the colour and the material you choose affects its properties. The purveyors of shingles know that this is a environmental design issue. Roofing materials now have a measurement of the solar reflectance and thermal emittances combined into a Solar Reflectivity Index. This indicates how much light is absorbed or bounced back into the atmosphere, and how much heat is absorbed and retained by the material, which is radiated to the surrounding environment, making buildings and cities hotter.

My choice of colour was “Classic Copper,” SRI = 54, which was only to be beaten on this matter by Silver (SRI = 72). Silver may sound strange, but it’s the the old-fashioned “Cat on a Hot Tin Roof!” colour that’s so nice to see on heritage housing. I even own a bunch of antique roofing shingles like this, for decoration purposes.

A week or two later, I got the answer from the borough: I could proceed with roofing my house with a new metal roof, using Wakefield Bridge shingles.

The Day of Work – gallery

The first half of the day, which began at 7 o’clock, the shingles came flying off the roof like a hurricane (abusing one of my tree branches in the process, though the branch leafed out again a few weeks later). Up to four roof deck boards would have been included as repairs if necessary, but even though I felt like it was almost guaranteed that one on the garage (the roof that’s seen the most wear) would need replacement, they were all fine!

By noon, the delivery truck with the crane arrived, and all the roofing materials were lifted up and put in place. From there, you can see how the work proceeded: applying the membrane, and installing the rows of shingles using good screws.

The first day, there were four in the work crew from 7–4 pm and then two continued until 7 pm. The second day, it was a three-man crew from 9 until 6 pm. And the third day, a two-man crew from 10 until 2. A final visit was necessary, as the roofer had to wait for the roof ridge shingles. He alone applied them, and my gutter guards in in the back of the house (one 23’ long eavestrough, hard to clean), in perhaps an hour and a half.

Neighbourhood feedback

Most people don’t usually make comments on roofs, or even notice them much, while passing by on foot. However, on the last day of the build, a city landscape worker was in the vicinity most of the day, such that I was wondering if she was a permit checker. (I displayed the permit in my window, so no worries.) At the end of the day she asked me about the roof materials and signaled her approval.

Better than that, the next week, a neighbour from the social housing apartment building a block away told me she lives on the 6th floor and looks down on our houses, and my roof is so nice to look down onto. As part of my “Beauty Will Save The World” ethos, if I can contribute to the view, well, that too is part of the reward in making solid environmental choices.

Cost

Another neighbour who lives in a house like mine came by to ask what it was made from, and how much it cost – telling me that some of his neighbours paid $10K for their roof.

I’ve already mentioned the estimate was three times that of asphalt shingles, and so that introduces what did it cost me? (Not $30K.)

A little south of $17,000, including the cost of the permits and extra supplies I needed (such as a box of rain gutter guards: $72 + tx).

The guy who estimated the materials overshot by several (at least four) pieces of flashing ($95 each), and four boxes of shingles ($235 each) –  basically enough for another garage roof like mine, so that was $1300 (+ tax) non-returnable/non-refundable. That’s less profit for the roofer, at least until he can find someone else who wants a copper-coloured roof and use those materials then. The roofers charged me the same as the promised estimate, with the roofing materials I paid for subtracted from the total, while they acquired some extra materials needed, like the roof ridge shingles and the ventilation stack. Obviously, the roofers are responsible for time spent planning the job and time spent in travel, both here and in taking the old shingles to the dump.

If, when winter comes, it turns out that I need ice breakers (points and shelves on the slope of the roof, to break sliding ice), then that was written into the estimate and I can call on it later. And the work is guaranteed for 10 years.

Final step

It’s a relief to finally have a roof that 1) looks this good, 2) matches my values in that it’s actually good for the environment compared to anything other than vegetation cover, and 3) to know it’s going to be intact and doing its job for basically the rest of my life. So the last thing I needed to do was call my insurance company to help them update the details for my policy.

My policy renews in January so funnily enough, I’m going to be getting a cheque back from them for $21. That’s maybe $40 off my annual premium. It’s kind of nice when that happens. $40 * 40 years = $1600 premium savings. Obviously, the value is a lot more.

  1. Internal benefits are the job a roof performs, like weather protection, rapid drainage and drying, wind resistance, protection from tree damage, fire resistance from flying embers, and energy efficiency in airflow for the attic. External benefits include fire resistance (obviously if your house roof is a fire break, it serves to help others) and the albedo reflective value for the climate, and immediate urban heat island mitigation. ↩︎