I’ve cut gable-end siding every way imaginable. When I first started working as a carpenter, I cut each piece one at a time, measuring the angles with a bevel square. Geeez was that slow!
It wasn’t long before I graduated to making a pitch block—a gauge block cut to the exact pitch of the roof. On production projects I could stack up six or seven pieces of fiber cement siding, hold my breath, and make that long rake cut with a circular saw. Usually the boards near the top of the stack came out straight, but the boards on the bottom half of the stack…well, not so much.
Then, one day on a neighboring jobsite, I saw a guy using a pitch block with a guide attached to one edge. Brilliant! I’ve made guide blocks like that for years, and I’ve even used some with a circular saw. I just hold the guide block and run the saw table right along the edge to keep the saw straight.
But one of the fastest methods I know of—if the framing is dead-on accurate—is gang cutting the gable-end siding.
The pitch of the roof is the first thing I need to know. Of course, if I’ve framed the roof myself, I know the exact pitch. But sometimes I work on remodels or follow behind other framers. When I first started working in construction, it used to surprise me to find roofs that were pitched at 6 3/4 in. or 5 3/8 in., but not anymore. Homes settle, green framing lumber dries out and changes, and sometimes the framers who built the roof just simply framed it to some odd pitch. At the end of the day, it doesn’t really matter. What does matter is determining the exact slope as easily as possible. Bevel squares and speed squares are great tools, but they just aren’t accurate enough over a long run. I calculate the pitch by drawing right on the gable-end wall.
With a long level—sometimes an 8 ft.’er—I mark a horizontal line on the wall, butting one end against the rake. Then I draw a plumb line up to the rake on the high side. I strike that plumb line at an even foot increment—like 5 ft., 6 ft., 7 ft., or even 8 ft., if I can reach out that far and the gable is wide enough. That way I know exactly how many inches the roof rises per foot.
After I’ve calculated the pitch of the roof, I lay out as many courses of siding as I can on my worktable, using cutoffs and scrap for the top pieces. I can pick any distance to measure in from the edge. On this small gable, I measured 3 ft. across for the run. Since the roof was cut at a 4/12 pitch, the gable climbed 4 in. for every 12 in. of run. So in 3 ft., the roof rose 12 in.
Laying out those dimensions is a snap—a lot easier than fooling around with a protractor. Before I had a track saw, I used to snap lines for these cuts, and then follow the chalk line with a circular saw, but I don’t do that anymore. I’m pretty good with a worm driver, but track saws cut a lot cleaner and more precisely. Besides, on this pre-finished siding, I didn’t want to snap chalk lines!
The only other measurement I need is the o.d. of the first (lowest) piece—from long point to long point. And that measurement has to be exact. Of course, there can be minor differences in succeeding pieces, and a tiny bit of wiggle room in the shiplap joint from course to course usually helps more than it hurts. I can always raise a piece of gable siding 1/16th of an inch if I need to. However, if the siding is too long, I have to climb down the ladder, cut the board, and seal the endcut again.
After plotting my mirror image points on the opposing side of the gable, I can lay my guide rail on the pencil marks. Next, I use my track saw—a contemporary carpenter’s newest friend—and make the long precise rake cuts on both sides of the gable. Then, I notch out the last piece with a jig saw so it fits nicely around the ridge.
This system of pre-cutting so many pieces works great for shiplap siding over a short run, but in my experience, it doesn’t work so well for lap siding, where the pieces can’t be held securely while I’m making the saw cut.
|Like any wood or wood product material, I also make sure to prime my cuts so they’ll stay straight and true long after I nail off the boards.|