Civil Engineering Reference
In-Depth Information
I prefer still another arrangement — that of the
porch roof joined to the main house roof, but at a flat-
ter slope. This gives the maximum height at the house
wall, allowing a deeper porch, which I like, still at a
sufficient slope. Shingling the joint where the porch
roof joins the main roof takes a bit of skill, but I under-
lay this with a strip of flashing. If you install a stand-
ing-seam porch roof, you'll crimp the vertical bends
of the metal, then hammer them flat before seaming.
We used to cut and solder here, but it's hard to avoid
leaks when you do it that way.
The porch roof slope that looks best with your
house is strictly a matter for your own eye, and as long
as the shakes shed water, you have quite a bit of lee-
way. I attach the house end of a porch rafter to the end
of a main rafter with one spike, letting the other end
pivot and hang down temporarily. Next I get help, if
necessary, to raise the porch rafter, swinging it up until
I get the slope I like.
I usually frame up the porch roof at the same time
as the main roof, so that I can go ahead with roofing.
I brace it temporarily, and sometimes frame and floor
the porch later. In pinning the rafter ends to the main
house, I use wooden pegs or long spikes, such as gut-
ter spikes. The same fastenings are used in pegging
the other ends of the rafters to the long stringer. This
stringer itself may be doubled and spliced 2≈8s,
because it should be the entire length of the porch, and
you may have trouble finding a single timber or pole
long enough. Usually we hew out a straight poplar
pole for this.
Three porch roof styles. At left is the “cat-slide”; center is the broken
roofline; and right is the separate porch roof, which is attached to the
house wall using flashing.
Any time the edge of a roof is up against another surface (such as a
chimney or a wall), you must install metal flashing along the incline.
Copper is best because the color tones down and disappears. How-
ever, use the same metal throughout, since no unlike metals should
touch or they will corrode. It is especially important to flash a porch
roof where it attaches to the main house. Here, the roof was not
flashed at all. Rain had been allowed to splash against the log and
funnel down the log wall. This caused the logs to stay wet and to
rot. Repairing this damage will be a major effort and expense.
