Learn how to create a CAD roof plan with this step-by-step guide, which includes creating layers, tracing a polyline around the building, and adjusting for roof overhangs and gutters. This article also highlights the importance of clean CAD drafting for precise and accurate architectural plans.
Key Insights
- The article provides a detailed overview of creating a roof plan on a CAD 301 plan model file. This involves creating specific layers such as the 'A roof outline' and 'A wall' layer.
- The process includes tracing a polyline around the building, ensuring to include specific architectural features such as fireplaces and columns, and adjusting for a 2 foot typical overhang, where the roof extends beyond the building.
- It emphasizes the importance of clean CAD drafting, which avoids overlapping or unnecessary line segments for a more precise and accurate plan. This includes adjusting polylines to reflect overhangs for covered porches and creating closed polylines for accurate roof plans.
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Let's begin working on our roof plan. Now, if you would please make sure that you are in your CAD 301 plan model file, because we're going to have the roof plan information on top of the floor plan information. Let's go to layers, and let's slide down, and let's make the layer A roof outline, our current layer.
And then if you would please, do a right button on the mouse, choose select all but current, turn all of them off by clicking on top of an on light bulb, and then you can just click again, it clears the screen, and then if you would please, turn on the A wall layer. With the A roof outline, what we're going to be doing is we're going to be tracing a polyline around the building. So I'm going to go into my OSnap settings, I'm just going to type OS, and I'm going to do a clear all, turn on end point, make sure it's turned on, and go okay, and then I will just draw a polyline, and I'm going to just start at a corner, and I'm working my way around the building.
Make sure you go around the fireplace, and I'm just continuing around the building, making sure that I'm seeing it go to the end point. I will click here, and then C to close. I'm going to draw a rectangle, and go around the columns, and once again, a rectangle, and go around the column there.
Control S to save. We have our roof outline done. Now you might be wondering, why is the line showing up dashed? The reason is that our A roof outline has a hidden line type defined within it, so when we imported the layers from our extraction model, we brought in the layer A roof outline, and we brought in the layer characteristics.
You might also be wondering, why is the line type scale showing up? The line type scale is showing up, because if I go format, line type, you can see that our global line type scale factor is 48, calculated in the model space environment, so we do not have used paper space units for scaling set. We have the outline. Now, if you look at the drawing, at your handout, you will notice, if you look at the dimensions in the top right-hand corner, that it's showing a 2 foot typical overhang.
This is where the roof overhangs the building. So again, we're talking to the framers, which is why we have our masonry layer turned off, so we're talking to the framers, and we're saying, let the overhang be 2 feet beyond the building. So I'm going to go into offset, and type in 24, enter, I pick, and I go out, enter, control S to save.
But, you can see that right now, we don't show the roof overhang on top of the covered porch. So what I'm going to do is this. I'm going to draw a line from the end of here, over to there, and I will draw a line from the end of here, up to here.
I will trim. These are my cutting edges. I pick there, I pick there, and I'm also going to pick here.
So the line segment that was there will be joining those two entities. So I have that geometry done. But, if you look right in through here, you can see that we have the polyline that ends there, and we have this other line that's joining up with that.
It's really not clean CAD drafting to have a polyline that goes there, and another segment that starts there, because again, you can see right here how it looks. We have a couple of options. The one I'm going to recommend is I'm going to use erase, and get rid of those segments.
I'm going to choose this polyline, pick the grip with ortho on, drag it horizontally, choose this grip, and drag it vertically. Hit escape, CTRL S to save. I will now trim using these endpoints, and say I'm done selecting, and I will choose these entities right there.
So I've now trimmed them, so I have a clean intersection, CTRL S to save. Now, what I'm also going to do is to make sure that this, in fact, is a closed polyline. So I'm going to choose the polyline, do a right button, go to polyline, edit polyline.
I will look at the command prompt. Do you see right here that it says open? Since it says open, that means that we have a closed polyline. If I choose open, see how it now says closed? Do you see what it did? How it got rid of that segment.
Whereas if I close it, the polyline is now a closed polyline. The last thing I want to do is to offset for the gutter. While I'm here, I will go into offset.
The distance of the gutter is three inches. I pick the line, I go out, enter CTRL S to save. So I have my outline of the building, I've cleaned up the polylines to reflect the overhang for the covered porch, but you can see that these entities are on the wrong layer.
I'm going to zoom in, I'm going to choose the inner rectangle, and I will map it to the layer A roof. And it's put onto a layer that's been turned off. That's fine, we're going to turn it on in a minute.
I'm going to select the other outline, and I will migrate it to the A roof gutter layer, which again is turned off. So it's fine, to an extent, saved. What we're going to be doing in a second is to start working on the hips and ridges for the roof itself.
So I'm going to go to layers, I'm going to turn on my A roof layer, and I will make it my current layer. My gutter layer I'm going to keep off for the time being. My roof outline, I can actually turn that off, I don't need it.
And I'm going to turn off my A wall layer. So again, what we're working with now will be the actual roofs, hips, and ridges. So let me give you a few minutes to get this done, and then we will continue on.