Design an accurate roof using AutoCAD, from blocking out the roof, creating slopes, all the way to generating overhangs and fascia boards. This guide offers a step-by-step process that any AutoCAD user can follow to create a detailed and precise roof design.
Key Insights:
- The tutorial starts by blocking out the roof, going up the thickness of the rafter or truss, and then the thickness of any top layer like a sheet of plywood. A rafter thickness of five and a half inches and a three-quarter inch sheathing are used in this example.
- The guide provides detailed steps on how to draw a 5'12 roof slope using AutoCAD's line tool, producing a triangle that represents the roof slope. Then, using the offset tool, the thickness of the rafter and the plywood are added to the slope.
- The tutorial then moves on to the creation of the overhangs and the fascia board, generating the top of the roof, trimming the walls to the correct height, and bringing down lines from the roof plan to generate the shape of the roof across the model.
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Let's start blocking out this roof. I'm going to start on the left side at the top of the wall and we're going to go up the thickness of our rafter or our truss and then the thickness of anything on top like a sheet of plywood for instance. And so we're going to use a rafter thickness of five and a half inches and a three quarter inch sheathing.
Now AutoCAD doesn't have a great way for us to draw this at a 5'12 roof slope. The best thing to do is to go over a distance of 12 and up a distance of 5. So let's do that. I'm going to go line, start here, go over 12 feet, enter, and then showing that 90 degree angle I'll go 5 feet, enter.
I'll close my triangle and hit escape, escape, escape. Now I can delete these two lines and we have our 5'12 roof slope. Let's use those two offsets that I mentioned.
Offset, a distance of 5.5, enter, and that's the thickness of our rafter or our truss. Enter to say I'm done, enter to go back in, 0.75 for our plywood, enter to say I'm done. Now there might also be a thickness to your roofing material but in this case we're going to ignore it.
So the only line that matters now is this top line. I'll select it and migrate it to A heavy, escape, escape. If you take a look at the handout you'll notice that these two objects aren't required anymore at all so we can delete them but we need to make sure that we can use the right geometry to mirror this line across so that we don't have to redraw it on the other side.
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What I need to do is mirror it to the exact opposite side of our wall so I'm going to use the mid between two points of this line and this line even though I'm pretty sure it's the midpoint of our finished floor line so that I have a roof slope facing up to the right and up to the left. So I'm going to go mirror this line, enter, from the shift right click mid between two points of this end point and this end point. I'll show my mirror angle by going straight up and down and click.
No I do not want to erase source objects and enter and I'll zoom in and CTRL S to save. One object snap that we turned on earlier but can get in the way as you're working is the perpendicular object snap. I'm going to jump down and turn that off from my running object snaps just so that we don't accidentally mess up as we're drawing the rest of this elevation.
Okay let's copy that roof slope line to the other parts of the roof. This one's going to get copied. I'm going to go copy from the end point here to this edge and the edge of our garage.
Enter to say I'm done. Enter to go back in. This one gets copied.
Enter to say I'm done selecting objects from this end point to here. Enter to say I'm done and that represents the top of each of roof slopes. This one is going to need to be generated using our roof plan which we'll do in a second but for now let's go ahead and use fillet and clean up these two roofs.
F enter. Make sure your radius is set to zero. Mine is so I'll pick here and here.
Enter to go back in here and here. Before we generate the top of this roof let's generate the overhangs. If we remember from our roof plan handout it says that there's a common two foot overhang so I'll go offset O enter.
Two feet enter and I'm going to offset to the left, to the left, to the right, to the left and again to the right on each side of my yellow line. Now I can use fillet. F enter again.
M enter for multiple to extend each of those lines and I'm using these offset construction geometry lines just to allow myself to extend those as far as I need. Enter to say I'm done and then we can keep these lines if we know what we need to do for our fascia board or you might want to delete them. For now I am going to keep them and I'm going to draw a new line from the bottom of my offset all the way across to this end point.
Let's do that together. I'm going to go to the line tool from this end point and I'm going to make sure to catch every end point just in case I want to change the layers that these are on in the future. For instance this line is fairly far back in the project when you look at the handout.
It's the fascia board towards the back of the roof. This could be on the A medium or A light layer so drawing one line all the way across is not as helpful than drawing these four individual segments. What that means is I now need to offset that individual segment four times so I'm going to go offset 5.5. This is a 2x6 fascia board.
Enter and I'm going to click and offset all four of these down to represent the edge of my roof. Enter to say I'm done and now let's trim up those additional overhang lines. Tr, enter.
T for cutting edges. It's going to be all four of these that I just generated. Enter to lock it in and then I can trim out those overhang lines.
Enter to say I'm done. Now one thing we also need to trim is the edges of our walls using those same four cutting edges. Enter to go back into trim.
T, enter for cutting edges. I'm going to pick those four again and I'm only going to pick on the yellow lines which are the walls that are cut. All of the blue green lines that represent our doors and windows I'm going to leave a little long.
That will help me to remember that it's construction geometry and we need to place real objects there as we move through this drawing. So I'm going to come into my yellow lines and click the top of each so that my walls are trimmed to the correct height. Enter to say I'm done.
Zoom out and CTRL S to save. The last thing I want to do in this video is to bring down the lines from my roof plan and using those I can generate the shape of this roof across my model. So I'm going to come up to here.
I don't need to change anything on this view for now. All I need to do is to turn on my A roof layer and bring down a few extra construction lines. XL for construction line.
