Green Part 5: Reroofing in an environmentally friendly way...

Is it possible to reroof a house without generating massive waste, to use materials that will last a long time and are recyclable at the end of their life? The answer is YES!!

A metal roof can minimize waste generation, be fully recyclable when it comes off, and also last a very very long time.

After a lot of thought and many discussions about esthetics, we decided to be a bit bold and install corrugated metal roofing. Originally we thought we would use a standing seam metal roof, but the architectural styling of that type of roof and the rest of the house seemed at odds. Our architect friend, Wade Skeels, suggested we use a high quality corrugated metal roofing, which he had used on his absolutely stunning farm house up in Marin.

Here are some of the reasons why we choose this roofing setup:

• If the current asphalt roof is in fairly decent shape (does not need to be great, just not leaking), and it is a single layer of asphalt shingles only, it is possible to leave it all in place to act as the waterproof underlayment and install the metal roof over the top. This immediately saves a lot of effort, and does not generate any new waste.

Here is the garage, which I did first to figure out all the details. You can see the furring strips that get installed over the asphalt shingles and into the roof joists. The corrugated metal panels then attach to the furring strips. It took me two weekends from start to finish to do the garage roof. It was a good confidence booster, but because the roof shape was so simple, it was not really a great test of the skills I would end up needing for the main roof. It took me almost 4 months to finish the main roof...

• Metal roofs are often made of painted steel. From what I could learn, the paint is PVC-based, which meant that was off the table. However, there is a much more environmentally friendly option which is a galvalume coating (not to be confused with a galvanization). Galvalume is a hot dipped coating of Al, Zn, and Si, where the Al makes up more than 50% of the coating so it is very resistant to corrosion. It is the coating of choice/necessity in a marine environment. It will never rust like old galvanized corrugated roofing material.

• The galvalume coated corrugated roofing material is considered to be a 75 year roof, and it is fully recyclable when removed. This is not your regular barn-style corrugated roofing material. The finish is high quality, and I chose a heavy gauge material -- which was described to me as being more "architectural".

• A galvalume finish is one of the most solar reflective options. This means that your attic and house stay much cooler.

• A metal roof is inherently fire-proof. Unfortunately, the rest of our house is not very fire-proof (yet...)

• Installing solar panels onto a metal roof (corrugated, or standing seam) is easy with the right connectors from S-5! (see the post about installing solar!)

Now for the downsides:

• The raw material cost is about 3x that of asphalt shingles. However, given their extended lifespan, the overall lifetime cost is very similar.

• Getting someone to install this type of roofing is not easy because it is not used that much. So for us, that meant doing it ourselves.

• Using a heavier gauge material means it gets heavy. I had to get creative with getting the panels safely up onto the roof!

Raising up each roof panel, one at a time with a winch, and a ramp (the top of which is the wood piece you can see at the edge of the roof. This was not physically too hard, just slow!

• Dealing with the more complicated features of many roofs, such as roof hips, valleys, dormers, and penetrations (the more fancy flashing situations) is not trivial. This became the biggest issue for me. I spent many many hours figuring out how to best handle some of these features, in part because there was a surprising lack of YouTube videos to rely on!

The valleys that ended on a roof, instead of at the edge of a roof (just right of the center of the picture, and then again to the far right of the picture) turned out to be very complicated. There was not a single YouTube video of this type of situation, so I had to make it up as I went. I think it turned out quite well, but it did require me to bend the flashing into the corrugated shape, which I hope to never ever have to do again.

I am particularly proud of the flashing on this type of penetration (which is missing the cap in this photo)... the normal way to handle it is to use a flexible silicone boot, and lots of sealant, but that just looks bad, and is incredibly unsatisfying to install. My method involved some fancy cutting and shaping of the upper flashing piece, but I think I managed to figure out a very water proof, long lasting, and pleasing flashing setup.

See also Green Part 6: Finally installing solar panels! and Green Part 7: Making full use of locally generated power