Metal Roof

 Okay, so it's hard to get a picture of the whole roof, and it's not even finished in this picture because we took the ladder down so as not to interfere with the ridge cap installation and then I forgot to take a wide-angle photo after the ridge cap was installed and then the ladder got moved and it's too heavy for me to set up by myself easily and and and...

I have a roof!

It only took a couple of days, too.

Every roofline will be different, but mine required three different types of flashing and one type/length of plain galvanized 12" Snap-Loc standing seam panel. That's about as simple as it gets, and not by accident: I did not want to deal with a complex roofline, because Lesson 52: the more complexities and corners and ridges and valleys, the more opportunities you have to mess up and cause yourself problems both long-term and short. I designed my roof to be a nice, flat, rectangular, unmarred, unpenetrated inclined plane, and it was a great decision.

First, the flashing. A roof needs flashing around the edges to cover the transition from roof deck to fascia and to guide water down and away from the roof, so it can't siphon up behind and underneath the roofing material. Each piece of flashing, therefore, has a little hem on the lower edge that juts away from the fascia and lets the water drip free. I opted for normal drip edge flashing for the bottom eave, "compensating" gable flashing for the gable ends, and what the supplier (Champion Metals) calls "shed metal"--a type of ridge cap--for the top eave.

With flashing and waterproofing, the correct sequence of installation and layering of products is crucial. I thought I had the order of operations all figured out ahead of time, but the fact of the matter is, Lesson 53: you should always just follow the specific manufacturer's instructions. The generic instructions I'd found online said to install 1) drip edge, 2) roofing felt/ice and water shield, 3) gable flashing, 4) roofing panels, and 5) ridge cap. That is not what Champion Metals' instructions were; their order of operations were 1) ice and water shield, 2) drip edge, 3) panels, 4) gable flashing, 5) ridge cap. This approach makes sense for their range of products, but might not for another company's. Just follow the instructions and don't take the internet's word for anything.
 

2/3 of the way there!

The roofing panels were pretty fun to install, truth be told. We took a good hour to install the very first panel, since if it wasn't perfectly straight, then the whole rest of the installation would go wonky. Lesson 54: take as much time as you need on the first course of any multiple-course installation. It pays off!

The rest of the panels really just snapped on, much as reputed. (Isn't that nice for a change?) We took care to align each panel so that it overhung the bottom eave by the right amount (1/2" in my case), drove bugle-head screws every 18-24" along the fastener flange, and then snapped the next piece on and repeated the procedure. We chose to lay down a bead of clear adhesive under the bottom edge of the panel, to prevent any water that got under the panel from below from seeping up. We also drove one watertight-washer roofing screw into the flat field of each panel at the bottom. Both of these precautions were suggestions from the manufacturer.

The only real difficulty we encountered was that some of our screws weren't biting into the plywood sheathing quite right. They would drive down most of the way, and then just spin without setting properly. We toyed with the torque setting on the screwdriver and eventually got most of them to set, but it was a frustration early on. It may have been easier if I had used thicker plywood than the 1/2" that I used--but weight and topheaviness was a bigger concern.

At the end of the installation, we trimmed off the last fastener flange because it overhung the end of the roof and fastened that panel with the roofing screws in the flat of the panel, next to the standing seam. Those exposed fasteners got covered up by the compensating gable flashing. "Compensating" means that the flashing covers more of the roof, in case the roof is out of square or something else went wrong to make the ridge not line up perfectly with the edge of the roof. The manufacturer recommended using compensating flashing if you're a first-time installer. We could have gotten away with the normal type, but better safe than sorry! It looks a little coarser, but whatever.

Notching the shed metal flashing

The final piece of flashing was a bit interesting to install. The shed metal ridge cap covers the transition between the upper edge of the panels and the upper fascia boards. For this piece of flashing to sit in place properly, notches had to be cut out for the standing seams. We borrowed a notching tool from the roofing distributor, held the flashing up to the roof to mark where each notch needed to go, and then started "notching out the returns," to use the trade lingo.

I'll be honest: I was pretty dubious as to how well the flashing would fit. As I held the flashing against the seams to get the marks, the flashing slid around, it was hard to mark the exact center of each seam, and when I brought the flashing down and measured between the marks to check, I found quite a bit of variability. Oh, dear...

But guess what?

Shed metal with notches notched

It worked!

So, so well!

Like, perfectly!

I was extremely pleased.

This piece of flashing, like the gable flashing, is fastened to the roof through the vertical face, into the fascia board. You use the roofing screws to do it, which remain exposed, so take care to mark out a nice, even fastener schedule!

The trickiest part of the shed metal was the corners. Champion Metals didn't specify how to deal with the corners, but I realized that unless we somehow folded the ends of the shed metal down around the corners, there would be an opening there and an opportunity for water to get in under the flashing and roof panels. Uh, oh.

Slightly ugly, but functional, corner

What made this procedure tricky was that A) angled sheet metal cannot be folded contrary to the existing fold, and B) those corners are actually compound angles: we would have to fold the shed metal 90º in the horizontal plane and 14º in the vertical plane. The 90º angle is easy enough: slit the top, remove the lip (the part we notched) so it doesn't get in the way, and snip the hem so it's just a flat piece of metal that you're attempting to fold. Adding the 14º angle was harder. Dad and I finally managed it by carefully cutting a slit at 14º, folding the metal down, and gluing and screwing (with a tiny sheet metal screw) the piece back together in its new position. It's not gorgeous, but it works!

Eventually the roof will have a gutter along the lower eave. This will take some figuring, though, because gutters are not available in sufficiently narrow widths to look okay on a tiny house. I may have to have custom gutters fabricated for me. Luckily, I have the right kind of flashing along my lower eave so I don't have to have gutters immediately, but it will be nice not to have a sheet of water flowing off my roof when the rain comes down hard...