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Al Whitley/5 min read

Working with Roof Slopes and Intersections: A Step-by-Step Guide

Roof Geometry Concepts

Ridge

Horizontal line where two roof planes meet at the top.

Hip

Sloping line where two roof planes meet at an external corner.

Valley

Sloping line where two roof planes meet at an internal corner.

Eave & Rake

Horizontal eave at gutter; sloped rake at gable end.

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This tutorial walks through working with roof slopes and intersections, covering essential tools and techniques for your projects.

Let's begin working on our roofs, hips, ridges, valleys, and all that good stuff. Now, if you look at the handout, you can see that the roof typically has a slope of 5 and 12. What that means is that for every 12 inches of run, the roof goes up 5 inches.

So it's a 5 and 12. It goes up 5 for every 12 inches. Because we have 5 and 12, or should I better say, because we have equal roof slopes on either side, when the roofs come together, they will be coming together at a 45-degree angle.

So I'm going to begin by drawing a line from this corner. And I'm just going to say at 12 feet, comma, 12 feet, Enter, Enter. So again, all I've done is I've brought in a line that's 12 feet long to the right and going up.

So this is going to be a typical condition where this side of the roof meets up with this side of the roof. I'm then going to mirror this line from the mid of this wall segment, or overhang segment, over to there. I'm then going to copy this to the end.

I'm going to copy this fellow over to there and also to here. I'm going to mirror. No, I'm just going to copy again.

I'll copy this segment over to here. Copy this segment over to here. And copy it here, here, and here.

I’ll copy this segment from here to here and over to here. Now it's time to start doing a little bit of cleanup. Ah, here's one thing I just noticed, is that in my roof itself, I have a covered area over the front door.

So I need to go back and make some changes. So I'm glad that I caught that. Here's one of the things I'm going to do.

I'll turn on my A-Roof Gutter layer. And I'll erase out these line segments. And I'm now going to go stretch.

So I'll say stretch. I’ll do a crossing over these segments. Press ENTER to say I'm done, from the end of the two-foot overhang above the front door.

And I'll make it perpendicular to the outside face of the building. So I’m picking over here. But if you look on the right, in a second, you’ll see that the perpendicular icon is there.

So CTRL+S to save. I'll now turn off my Roof Gutter. And again, the reason I’m keeping the gutter layer turned off is to make sure that I’m attaching to the right lines.

I’d rather attach to the roof overhang and not to the gutter. So I’ll now copy this line segment from here to here. And copy this segment from here to here.

CTRL+S to save. So I’m glad that we caught that. Now again, if I were to turn on the Roof Outline layer, you can see how the building comes back here.

And there's a covered area over the front porch. Once again, I’m going to turn off my Outline layer. I'll start off by doing some cleanup in through here.

I’ll draw a line from the intersection to the intersection. Then I’ll use Trim.

These are the cutting edges. Press ENTER to say I’m done selecting. And I’ll delete these segments.

CTRL+S to save. Now, as I look around the handout, I can tell that I’m going to be needing to work with intersection a fair amount. So I’ll go to my OSnap icon down here.

Do a right-click. Go to Settings. And I have End Point on.

I’ll also turn Intersection on. I’m going to zoom into this area. And now I’ll clean up here.

This will be a fillet. So I’ll go to Fillet. Check the radius.

Ah, it's a two-foot radius from what we were working on before. So I’ll do a right-click. Let my radius value be zero.

And I’ll select these segments right there. I’m going to draw a line from the intersection here horizontally. And I’ll use Extend.

There’s Trim. And there’s Extend. I’ll extend this segment to here.

I'm going to fillet. Again, look at the radius of zero. Fillet these segments together.

But what's happening is this is sort of architectural complication. The roofs right here will actually meet at a rising spot in the roof. So I’m going to copy this line, the 45, from here to here.

And then I'll trim. These are the cutting edges and this too. And I’ll delete that segment and that segment.

I'll now draw a line from the intersection here over. And once again, trim crossing. And I’ll select to delete these entities here.

So what's happening is you can see the roof comes up. It levels out here so we can get this panel of the roof. But the roof will continue to rise along the front so that this segment can meet up with it.

I’m now going to mirror this line to here. And I’ll do some trimming and cleanup. I’m going to fillet these segments here and this segment here.

And then I have a panel that’s going to be happening here. So I’m actually going to extend this segment to here. And I’ll trim that.

And I’m going to draw a line from here straight down. You can see how everything marries up. And I’ll trim these segments.

So again, what we have going on is we have the roof panel here, another panel here, a panel here. So the roof is continuing to rise up to that point. And we have this panel over here.

So I’m going to save this drawing. And in a couple of minutes, we’re going to come back and begin laying out the drawing to be considered for our roof plan sheet file.