Discover how to add and modify roof geometry in your architectural designs using relative coordinates, offsets, and other tools. Learn how to use slope and other roof details to accurately represent roofing structures in your designs.
Key Insights
- The article demonstrates how to use relative coordinates and slope details to accurately create a roof's geometry, including the bottom line of rafters and additional elements like underlayment and roofing material.
- The author emphasizes the use of offsets to account for the width of certain elements such as a two by four or a two by six fascia board. This helps to create a more realistic representation of the roofing structure.
- The tutorial guides through the process of cleaning up the design by using fillet commands, trimming, and adding in square cuts to represent the correct geometry of the roof.
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In this video, we are going to add our roof geometry. In order to do that, we need to see our roof geometry.
We have some geometry to pull from. Let's go to our layer dropdown, and let's turn on our A roof layer. There we go.
Now we can see our roof geometry. Remember, our slope established that the roof slides from the ridge here, down to the left, and from the ridge here, down to the right. If we take a look at our roof plan handout, we can see that the slope is four colon 12.
That means it's a rise of four for a run of 12. That's four inches and 12 inches, or four feet and 12 feet. Also, if we look at the handout, we see that this datum here is called the top of plate.
What that means is that the structure of our walls ends at this line, and that is where the roof rafters would sit. So in order to combine all of this information, we need to know that this point right here, where my wall geometry lines up with that top of plate geometry, that is where the bottom of our rafters will be. The rafters in this case are three and a half inches, as they are two by fours.
So let's start by drawing our bottom line of that two by four, and it's gonna come up in this direction here. Okay, so let's get going. I'll go line, and in this case, our first point will be here, and in this case, our second point will be a relative coordinate.
We do not know the angle, and we do not know the point of this coordinate absolutely from where we just chose. We need to use a relative coordinate. So I'll type at 12 feet, comma, four feet, and that's because I'm moving in the positive direction in X, and I'll move up, which is the positive direction in Y. Okay, I'll hit ENTER, Enter to say that I'm done, and there we go.
That's our first line of this roof. Now, the three and a half inches is our width of the two by four, so let's make that offset first. Offset, 3.5, Enter, and I'll go up and click, Enter to say that I'm done.
That's our first part of our roof geometry, but then on top of that, there's probably about an inch of underlayment and roofing material, specifically our composition shingles. So let's offset one more time a distance of one, Enter. I'll click here and go up and click, Enter to say that I'm done.
Our two by four is not going to be visible on this drawing. It's actually hidden behind our two by six fascia board. So I can grab those two lines that represent our two by four and hit Delete.
So this is the only line we need, the top of our roofing material, but you can see on the handout that we have a two by six fascia, and the two by six in railroad geometry is 5.5 inches wide. That's its railroad size compared to the nominal size. Now we need to offset from this point back down five and a half inches.
Offset, 5.5, Enter. I'll grab this point and go down and click, Enter to say that I'm done. Now, I'm not gonna clean up any more of that geometry.
Instead, we'll repeat that process on this side, and then we can clean it up together. Okay, let's turn off Ortho, and let's do that same process here. So I'll go Line, clicking this endpoint.
Now, I'm going in this direction this time. It's still a relative coordinate, but this time it's at negative 12 feet, comma, four feet. We're going in the negative X and the positive Y, Enter, and then Escape, Escape, Escape.
Here, the offset is going up three and a half, and then one. So our offset distance is 4.5, Enter. Here to here, Enter to lock it in.
Go back in one more time, Enter, 5.5, Enter. From this top line, back down and click, Enter to say that I'm done. Now, this line right here, we don't need anymore, so we can delete.
There we go. That's the outline of our fascia board. Let's clean it up a little bit.
At the top, that's a fairly easy solution. We just need some fillets. But how do we clean up our sides here and here? Well, we can see our geometry up above.
Here is where the roof goes. It's one foot away from the wall, and here. So let's draw some rays down so that we can use it for our geometry.
I'll draw a ray here and here. I have a perpendicular snap, but I'll turn on Ortho. Clicking down, Enter, Enter to go back in.
This end point, down and click, Enter to say I'm done. Now two rays have come down, and I can snap or trim or fillet to that geometry. I'll turn off Ortho and Control S to save.
Okay, so let's get this workflow done. I'm going to use the fillet command for all of these connections. So follow along with me.
Fillet and then multiple, M, Enter. I'm going to click this line and then this line. That's cleaned up the point right there.
Then the top two here and here. That's cleaned up both of these points now. And now I'm going to click this line and the bottom of my ray.
And then I'll click this line and the top of my ray to create a plum cut. And then this line and the bottom. And then this line and the top.
Again, creating a plum cut. Now on the handout, you can see that we use a square cut, not a plum cut. So while we use that geometry to clean up these lines, I can now delete these two plum cut geometry lines, and we need to add in square cut.
If we go to our object snaps, we can see perpendicular is still on. So I can come in here and with a new line, draw from this end point here to the perpendicular here. Click, Enter to say that I'm done.
And I'll come over here and do the same thing. From this end point to the perpendicular here. Enter to say that I'm done.
And now we can fillet or trim these back together. In this case, I'll just use fillet. Fillet here to there.
And fillet here to there. Before we go away, there's one more small trim that we can do. If we zoom way in, we see this yellow line crosses.
Let's go ahead and trim that out on this side. Enter to say that I'm done. And pan over, go back to trim, and trim it out on this side.
Enter to say that I'm done. All right, I'll do a zoom extents, and Control S to save. In the next video, we are going to add our UCSs, which is the user coordinate system, and our named views.
We can start to put our geometry on our other views.
