Chapter 4
IN THIS CHAPTER
Drafting a simple floor plan
Going from a 2D plan to a 3D model
Adding floors, doors, and windows
Modeling stairs
Building a roof
Even though SketchUp lets you make (just about) anything you can think of, certain forms are easier to make than others. Fortunately, these kinds of shapes are exactly the ones that most people want to make with SketchUp, most of the time. That’s no accident; SketchUp was designed with architecture in mind, so the whole paradigm — the models made of faces and edges, and the kinds of tools SketchUp offers — is perfect for making things like buildings.
But what about curvy, swoopy buildings? You can use SketchUp to make those, too, but they’re a little harder, so we don’t think they’re a good place to start. Because most people live in boxy places with right-angled rooms and flat ceilings, that kind of architecture is relatively easy to understand.
In this chapter, you discover some fundamentals of SketchUp modeling in terms of making simple, rectilinear buildings. By writing about how to build certain kinds of things, instead of just describing what the individual tools do, we hope to make it easier for you to get started. Even if you’re not planning to use SketchUp to model any of the things we describe, you can still apply these concepts to your creations.
Most floors and walls are flat surfaces, so it’s easy to model them with straight edges and flat faces in SketchUp. In fact, chances are good that the first thing you ever model in SketchUp looks a lot like the floor and walls of a building.
How you approach modeling floors and walls depends entirely on the type of model you’re making:
You can model a building’s interior in lots of ways. In this section, Aidan shares the method he developed over years of creating SketchUp models. Basically, you draw a two-dimensional floor plan that includes all your interior and exterior walls, and then pull it up to the right height (extruded). Only after your model is extruded do you worry about doors, windows, and stairs.
Before you draw a 2D plan, you need to orient your point of view. Drawing in 2D is easiest when you view your work from directly above, looking down at the ground plane. You also want to make sure that you’re not seeing things in perspective, which distorts your view of what you have.
Follow these simple steps to set up your SketchUp modeling area for 2D drawing:
Create a new SketchUp file by choosing File ⇒ New.
Depending on the template you have set to open when you create a new SketchUp file, you may already be in a 2D view. If all you see are the red and green axes on a white background, you can skip Step 2. Remember that you can always switch templates by choosing Help ⇒ Welcome to SketchUp and clicking the Template section of the dialog box that pops up.
Choose Camera ⇒ Standard ⇒ Top.
This changes your viewpoint so that you’re looking directly down at the ground.
Choose Camera ⇒ Parallel Projection.
Switching from Perspective to Parallel Projection makes it easy to draw plans in 2D. At this point, your modeling window looks like the one shown in Figure 4-2.
You don’t need many tools to draft a 2D plan in SketchUp. Figure 4-3 shows the basic toolbar; everything you need is right there:
Offset tool: The Offset tool helps you draw edges that are a constant distance apart from edges that already exist in your model. Pictures are usually better than words, so take a look at Figure 4-7. Using Offset on the shape creates another shape that’s exactly 6 inches bigger all the way around (middle image), or 6 inches smaller all the way around (right image). Offsetting edges is a useful way to create things like doorways and window trim.
You can use Offset in two ways; for both ways you click once to start offsetting and again to stop:
If all you’re trying to do is model an exterior view of a building, just measure around the actual building’s perimeter, draw the outline of the building in SketchUp, pull it up with the Push/Pull tool, and delete the top face if you like, as shown in Figure 4-9. Then you can add your desired roof, as explained in “Raising the Roof” later in this chapter. With this method, your walls are only a single-face thick (meaning paper-thin), but that’s okay. You’re only interested in the outside, anyway.
Measuring an existing building so that you can model an interior view is easier said than done. Even experienced architects and builders often get confused when trying to model the interiors of as-builts, which are drawings of existing buildings. Closets, ventilation spaces, interior walls, and all kinds of other obstructions inevitably get in the way of good measurements. Usually, you give the measuring your best shot and then tweak things a bit to make them right. The following sections walk you through the process.
When you model a building's interior, your main goal is creating accurate interior spaces. To achieve that accuracy, work from the inside out. If your tape measure is long enough, measure the major dimensions first. That is, measure the total interior width and length of the building's inside. You may not be able to, but do your best. After that, just work your way around, using basic arithmetic and logic to figure out the size of the space.
From this paper drawing, here’s how you draw a basic interior outline of this house:
Switch to a 2D overhead view.
The section “Switching to a 2D view,” earlier in this chapter, explains how.
Using the Line tool, draw a line that represents the exact length of a wall in the house.
For example, Aidan starts drawing his house's eastern wall by creating an line that's exactly 17 feet long. (See the top-left image in Figure 4-11.)
To draw a precise line, click once to start the line, click again to end the line, type 17', and press Enter. Remember you don’t need to click anywhere before you type a precise value; the Measurements box listens for your keystrokes immediately after you draw something. After you press Enter, the line resizes itself automatically to be exactly 17 feet in length. If you want, you can use the Tape Measure to double-check the size.
Connect the next edge to your first one.
As shown in the lower-left image in Figure 4-11, Aidan works clockwise, drawing an edge 11 feet, 10 inches long, starting at the end of the first edge and heading to the right in the red direction.
Keep going all the way around the house, until you get back to where you started. See Figure 4-12.
If you make a mistake, use the Eraser to get rid of edges. Alternately, undo by pressing Ctrl+Z (⌘+Z on the Mac) or choosing Edit ⇒ Undo to go back a step or two.
If all your measurements don’t add up, adjust things so that they do — a few extra inches here and there never killed anyone, after all.
After you complete the outline (forming a closed loop of edges that were all on the same plane), a face automatically appears. Now you have a total of 11 edges and 1 face.
With the Offset tool, you can offset an exterior wall thickness, which can make it easier to visualize your spaces. Here’s how you do it:
Using the Offset tool, offset your closed shape by 8 inches to the outside. See Figure 4-13, upper left.
An offset of 8 inches is a pretty standard thickness for an exterior wall, especially for houses in Aidan's neck of the woods. See “Dusting off SketchUp's drafting tools” earlier in this chapter for details about using the Offset tool. After you create the offset, type 8" and press Enter.
With the Eraser tool, delete the extra edges. See Figure 4-13, middle left.
By deleting the extra edges, you have only two faces: one that represents the floor and one that represents the wall.
With the Line tool, draw edges that define the thickness of your exterior wall. See Figure 4-13, middle right.
For this example, Aidan separated the bulges (which actually represent a fireplace and a mechanical closet) from the part of the wall that goes all the way up to the roof, two stories up.
When you’re done, you end up with several faces: one for the floor, one for the exterior wall (whose thickness should be more or less uniform), and a few for the bulges.
Select the face that defines the exterior wall. See Figure 4-13, lower left.
The easiest way to do this is to click the face with the Select tool.
Make the face you just selected into a group. See Figure 4-13, lower right.
Chapter 5 is all about these groups (and their über-useful cousins, components), but here’s all you need to know for now: Making groups lets you separate different parts of your model. Turning your exterior wall into a separate group makes it easier to edit, hide, and move. Groups also simplify the process of adding more levels to your building, if that becomes necessary.
To turn the face you selected in Step 5 into a group, choose Edit ⇒ Make Group. You see a perimeter of blue lines around your face; that’s the group you just created. Congratulations — you’re now officially an intermediate SketchUp user.
For this part of the process, guides are your friends. Chapter 3 has a section on guides, where you find a full description of guides and how to use them.
Working from your 2D drawing, here’s how you create interior walls:
With the Tape Measure tool, create guides to mark the precise location of the interior walls.
For example, the guide for the wall in the lower right of the sketch (Figure 4-10) is a parallel guide 5 feet, 3½ inches from the inside of the entryway. See Figure 4-14, left. Figure 4-14, right, shows all Aidan's guides.
To create a parallel guide, click the edge from which you want to draw the guide, move your cursor (to tell SketchUp which way to go), type your distance (such as 5'3.5), and press Enter.
With the Line tool, draw edges to represent the interior walls.
With guides, it’s easy to draw your edges correctly. Figure 4-15 shows what you have so far.
Don’t forget to zoom! When you have a jumble of edges and guides and you can’t see what you’re doing, just zoom in. Many folks forget to change their point of view while they work, and zooming makes all the difference.
Use the Eraser to delete extra edge segments. See Figure 4-16.
The goal is to have the smallest-possible number of 2D faces to extrude into 3D walls, a little later on.
Because the exterior-wall face — and the edges that define it — is part of a separate group, accidentally nicking it with the Eraser deletes the whole thing. If this happens, just choose Edit ⇒ Undo to go back a step, zoom in a little bit, and try again.
With a 2D plan in hand, you're ready to extrude it into a 3D model. This process is enormously enjoyable and involves the tool that made SketchUp famous: Push/Pull. In the following sections, you take a simple floor plan (the one you draw earlier in this chapter) and turn it into 3D walls.
Before you pop up your plan into the third dimension, change your point of view to get a better view of what you’re doing. See Figure 4-17 and follow these steps:
Choose Camera ⇒ Perspective.
This turns on SketchUp’s perspective engine, meaning that now you can see things more realistically — the way people really see things in 3D.
Choose Camera ⇒ Standard ⇒ Iso.
This switches you from a top view to an isometric (three-quarter) one. You can do this with the Orbit tool, too. SketchUp usually gives you more than one way to do something.
Choose Camera ⇒ Zoom Extents.
Zoom Extents has its own button on the Getting Started toolbar, but we're sticking with the Camera menu theme, just for consistency.
Choose Camera ⇒ Field of View, type 45, and press Enter.
You’ve changed the field of view from 35 to 45 degrees. By default, SketchUp’s field of view is set to 35 degrees. (For more information on what this means, check out Chapter 11.)
The Push/Pull tool is a simple creature: It extrudes flat faces into 3D shapes. To use Push/Pull, click a face once to start pushing/pulling it, move your cursor until you like what you see, and then click again to stop pushing/pulling. That’s it. No software tool has ever been so satisfyingly easy to use and understand. For more detail on Push/Pull, see the nearby sidebar, “More fun with Push/Pull.”
The following steps outline how to use Push/Pull to extrude an interior floor plan into a 3D model, as shown in Figure 4-18:
Select the Push/Pull tool from the toolbar.
The tool looks like a little box with a red arrow coming out the top.
Click an interior wall’s face to start extruding it.
If you click the “floor” face, you’d extrude that instead. If you accidentally choose the wrong face, press Esc to cancel the operation and try again.
Move up your cursor to pull up the wall; click to stop extruding.
How much you extrude the face doesn’t matter, because you add precision in the next step.
Type a ceiling height (such as 8') and press Enter.
When you do this, the push/pull distance is revised to reflect your exact ceiling height. In this house, that's 8 feet.
Repeat Steps 2 through 4 for all the interior walls.
As explained in Chapter 3, orbiting helps you view what you’re doing as you work around the model.
Push/pull the exterior wall to match the height of these interior walls.
Because the exterior wall face is part of a group, you need to “open” the group before you can do anything to it. To open a group, double-click the exterior wall face, or context-click it and choose Edit Group. After you're able to work inside the group, you can follow Steps 2 through 4 in the preceding steps to make the exterior wall group 3D. Click anywhere outside the model to exit the group when you’re done.
Adding a second (and third, and fourth) floor to your model isn’t as hard as it may seem. The key is to think of each level as a separate “tray” consisting of interior walls, a floor surface, and the ceiling of the level below. You model each floor as an individual group, making it easier to hide, edit, and move.
For the same reasons, you also make the exterior walls a separate group. They act kind of like a “box” into which your floor levels stack, as shown in Figure 4-19.
If you’ve been following along since the beginning of this chapter, the edges and faces that make up your exterior walls are already enclosed in a group by themselves. If they’re not, seriously consider doing that now. If you take the time to group your exterior walls before you add floors to your building, you save hours of headache later. Trust us.
If your exterior walls are already a group, the next step is to turn the rest of your first floor’s geometry into another group. This is how you do just that:
Select the floor and interior walls of the first level.
You can accomplish this efficiently with the Select tool: Just triple-click a face on any interior wall to select everything that’s attached to it. Chapter 3 has plenty of tips on selecting things.
Make a group by choosing Edit ⇒ Make Group from the menu bar.
Chapter 5 is all about groups and components; peruse the first few pages if you’re utterly confused about what just happened.
Modeling each new floor directly on top of the one underneath guarantees that everything in your building lines up. Some folks advocate for working “off to the side” and putting things together later, but Aidan finds that a recipe for trouble. Here’s how you add a second floor to the house model. Check out Figure 4-20 to see the steps as pictures:
With the Line tool, trace the inside perimeter of the exterior wall to create a new face.
Keep in mind that tracing works only if everything you touch is already part of another group. If it isn’t, your new edges stick to your existing ones, and your model becomes very, very messy.
Push/pull your new face into a thick slab.
How thick? It depends on your building, but a reasonable ceiling-to-floor distance between levels for houses is about 1 foot. You can figure yours out with a tape measure and a calculator.
The underside of the new slab is the ceiling of the first floor. Modeling buildings this way improves visibility because it enables you to hide a floor group to see the one below it.
Draw the interior walls of the new floor.
This is just like drawing the first floor. Switch to the Top view (Camera ⇒ Standard Views ⇒ Top) and then use the Tape Measure, Eraser, and Line tools to draft your floor plan. Just start at the very beginning of this chapter for a refresher.
If the floor you’re drawing is bigger than the one below it, its outline overlaps the exterior walls. That’s okay — just pay special attention to where your edges and faces end up as you draw. Orbit every once in a while to check that everything’s copacetic.
In the event that your new floor is smaller than the one underneath, represent the inside boundary of the new exterior walls with a single edge. The next section explains what to do when your first and second floor plans don’t match up exactly.
Push/pull your interior walls to the correct height.
That’s 8 feet, in this example.
Group together your interior walls, your floor, and the ceiling of the level below.
If you’re unsure of how to do this, take a look at the steps in “Making groups to keep things separate,” a few pages back.
If your upper floor isn’t bigger or smaller than your lower floor, pull up your exterior walls to match your interior ones.
Here you’re extending the box that holds your floor trays up another level. See the last step in “Push/pulling your way to happiness” earlier in this chapter for details.
Most buildings aren’t simple extrusions; they bump in and out as they rise. Second-floor decks sit atop first-floor garages; bedrooms cantilever over gardens; intermediate roofs shelter new room additions. Buildings — especially multilevel houses — are complicated assemblies. Figuring out where walls, floors, and ceilings come together takes time, trial and error, and a good dose of spatial reasoning. It’s best not to attempt the steps in this section when you’re tired or distracted.
In the house Aidan models for this chapter, the second floor both overhangs and, um, underhangs (hooray for neologisms) the first floor. Wherever this happens, you need to add a new section of exterior wall, as shown in Figure 4-21.
To begin the second floor, draw faces to define any new exterior walls. Follow these steps, which correspond to Figure 4-22:
Hide the group that includes your second-floor interior walls by context-clicking it and choosing Hide.
You created this group by following the steps in the preceding section, “Drawing the next floor.”
Select the face that you created when you traced the inside perimeter in Step 1.
Don’t see a face? Maybe you forgot to draw an edge somewhere.
With the Offset tool, offset the edges of your selected face by the thickness of your exterior walls.
In this case, the thickness is 8 inches.
After you define the exterior wall face, you fine-tune how the second floor rests on top of the first floor by following these steps:
Delete any floor geometry that doesn’t belong.
For example, in Figure 4-23 (top), part of the second floor extends past the exterior wall on the left side of the figure. Double-click the group with the Select tool to edit it, and then use the Eraser to take away only the geometry that doesn’t belong on your new floor, being careful to leave the ceiling that covers the first floor.
Only now are you ready to ensconce your second floor in its new exterior walls. Doing so is yet another multistep process:
With the Select tool, double-click the group containing your lower exterior walls.
You’re “inside” that group.
Choose Edit ⇒ Group ⇒ Explode to ungroup the edges and faces in the selected group, sticking them to those in the lower group.
Whew.
With the Line tool, add any necessary edges. With the Eraser tool, delete any extraneous ones.
In Figure 4-24, you can see where the model has extra edges that need to be deleted.
Using your SketchUp virtuosity, watch the colors as you draw, use the Shift key to lock inferences, and remember to zoom in on what you’re doing. Skimming Chapter 3 provides useful pointers on these actions.
Orbit around your model to make sure all is well.
You can see the result in the lower right of Figure 4-24.
To add doors and windows, the best method depends on what kind of building you’re modeling, whether you’re using single-face or double-face walls, and how much detail you plan to include in your model. You can make openings in your walls in a couple ways:
As long as you’re making an exterior model, you can use the door and window components from SketchUp’s 3D Warehouse. Without going into a ton of detail, here’s what you need to know about them:
Follow these steps to add a door or window component to your model:
With the Tape Measure tool, create guides to help you line up your doors or windows.
Guides are the best way to ensure that everything’s in the right spot. In Figure 4-25, two horizontal guides (which are 2.5 feet from the bottom of the exterior wall) mark where to place the bottom of the windows. One vertical guide marks where to place the right edge of the door. After Rebecca placed the door, she created a guide 4 feet from each side of the door, to help place the windows symmetrically. Chapter 3 explains how to create guides.
In the Components panel, select the component that you want to place in your model.
For help navigating the Components panel, see Chapter 5.
In the drawing area, click to place the component where you want it to be.
In Figure 4-25, you see one door and four instances of the window component.
Most of the time, you can’t get away with using SketchUp’s built-in door and window components. Because these components can’t cut through two-faced walls, they’re limited to external use only. That’s okay though; cutting your own holes in walls is quick and easy, and you end up with exactly what you want.
To cut a precise opening in a double-face wall, here’s what you need to do; Figure 4-26 shows the basic steps:
Mark where you want your opening to be with guides.
For a refresher on using guides, have a look at Chapter 3.
If you’re drawing on a wall that’s part of a group, you need to edit that group in order to punch holes in the wall. To edit a group, double-click it with the Select tool. To stop editing, click somewhere off to the side of your model. Chapter 5 has more info about working with groups.
Draw the outline of the opening you want to create, making sure to create a new face in the process.
Use the Line tool, and keep an eye out for the colored inferences, which let you know where you are.
With the Push/Pull tool, extrude your new face back into the thickness of the wall until it touches the face behind it.
If everything goes well, your face disappears, taking with it the corresponding area of the face behind it. Now you have an opening in your wall. If your face doesn’t disappear, and no opening is created, it’s probably for one of the following reasons:
You can make stairs probably a million different ways in SketchUp, and in the following sections, you find two methods that work equally well.
Chapter 5 contains a third, slightly trickier (but way more powerful) way of making stairs using components. SketchUp’s Dynamic Components have some pretty neat implications for models that need stairs. A so-called dynamic stair component automatically adds or subtracts individual steps as you make it bigger or smaller with the Scale tool. Depending on what you want to accomplish, a premade dynamic stair component may save you a bunch of time. Find out more about them in Chapter 5.
Before you dive in, here’s some simple stairway vocabulary, just in case you need it. Figure 4-27 provides a visual reference:
The Subdivided Rectangles method is how most people think to draw their first set of stairs. This method is intuitive and simple, but a bit more time-consuming than the other methods in this book.
Here’s how the Subdivided Rectangles method works. See Figure 4-28:
With the Select tool, context-click a long edge of your rectangle and choose Divide.
If your staircase is wider than it is long, context-click a short edge instead.
Before you do anything else, type the number of treads you want to create and press Enter.
This command automatically divides your edge into many more edges, eliminating the need to calculate how deep each of your treads needs to be. Essentially, each new edge becomes a side of one of your treads.
Draw a line from the endpoint of each new edge, dividing your original rectangle into many smaller rectangles.
You can use the Line or the Rectangle tool to do this.
Use the Divide command to split your new edge into however many risers you need in your staircase (generally your number of treads, plus one).
Repeat Steps 2 and 3 to do this. The endpoints of your new, little edges tell you how high to make each step.
Push/pull the rectangle that represents your last step to the correct height.
Here’s where you need to use the hover-click technique that we describe in the sidebar “More fun with Push/Pull,” earlier in this chapter. Just click once to push/pull, hover over the endpoint that corresponds to the height of that tread, and click again. Your step is automatically extruded to the right height.
Extrude your highest step first, but remember that it doesn’t go all the way to the top. You always have a riser between your last step and your upper floor.
Use the Eraser to eliminate extra edges you don’t need.
Don’t accidentally erase geometry on the part of your staircase you can’t see. Turning on Back Edges (View ⇒ Edge Style ⇒ Back Edges) is a nice way to see “through” your model without resorting to X-Ray mode.
This method for modeling a staircase relies, like the last one, on using Push/Pull to create a 3D form from a 2D face, but this method is more elegant. In a nutshell, draw the profile — the side view, sort of — of a single step and then copy as many steps as you need, create a single face, and extrude the whole thing into shape. The first time you do this is breathtakingly satisfying — one of those “guaranteed to make you smile” SketchUp operations you’ll want to repeat for friends (assuming you have nerdy friends like us).
Follow these steps to make a staircase using the Copied Profile method, as shown in Figure 4-29:
Start with a large, vertical face; make sure that it’s big enough for the flight of stairs you want to build.
You’re going to end up pushing/pulling the whole shebang out of the side of this face, just so you know.
In the bottom corner of the face, draw the profile of a single step.
The Line tool is a great choice, although you may want to use an arc or two, depending on the level of detail you need. For a refresher on drawing lines accurately, check out Chapter 3.
Select all the edges that make up your step profile.
You can hold down the Shift key while clicking with the Select tool to select multiple entities. Chapter 3 has lots of selection tips.
Make a copy of your step profile and place it above your first one.
If you’re unfamiliar with how to make copies using the Move tool, see Chapter 3.
Type the number of steps you want to make, type x, and then press Enter.
For example, if you want ten steps, type 10x. This technique repeats the copy operation you just did by however many times you tell it to; the x after the number tells SketchUp to make copies.
Push/pull the staircase face to reflect the desired width of your staircase.
This part seems like magic to most folks; we don’t think it ever gets old.
If you’re lucky, the roof you want to build is fairly simple. Unfortunately, home builders sometimes go a little crazy, creating roofs with dozens of different pitches (slopes), dormers, and other doodads that make modeling them a nightmare. For this reason, this section keeps things pretty simple: The following sections show you how to identify and model basic roof forms. After that, you discover a great tool — Intersect Face — that you can use to assemble complicated roofs from less-complicated pieces.
Before you dive in, here's a brief guide to general roof types and terminology that may come in handy for the explanations later in this chapter. Figure 4-31 illustrates each of the following terms:
Good news! SketchUp was practically made for modeling these kinds of roofs. By using a combination of the Offset tool and Push/Pull, you can make a parapet in less than a minute. Follow these steps, as shown in Figure 4-32:
Type the thickness of your parapet and then press Enter.
This redraws your offset edges to be a precise distance from the edges of your original face. How thick should your parapet be? It all depends on your building, but most parapets are between 6 and 12 inches thick.
Aidan's favorite way to create eaves, or roof overhangs, is to use the Offset tool. Follow these steps to get the general idea and see Figure 4-33:
Make a group out of your whole building before you start modeling the roof.
Keeping your roof separate makes your model easier to work with.
With the Line tool, create an outline of the parts of your roof that will have eaves of the same height.
The goal is a single face that you can offset. A lot of buildings have complex roofs with eaves of all different heights; for the sake of this step, just create a face that, when offset, will create roof overhangs in the right places.
With the Offset tool, create an overhanging face.
For instructions on how to use Offset, see the section “Dusting off SketchUp’s drafting tools,” earlier in this chapter.
Erase the edges of your original face.
Here’s a quick way to do this with the Select tool:
Double-click inside your first face.
This selects both the face and the edges that define it.
Push/pull your overhanging roof face to create a thick fascia.
Different roofs have fasciae of different thicknesses; if you don’t know yours, just take your best guess.
You can construct a gabled roof in a bunch of ways (every SketchUp expert has her favorite), but one method works particularly well.
Follow these steps to build a gabled roof, which is shown in Figure 4-34:
Create a roof overhang, following the steps in the preceding section.
Most gabled roofs have eaves, so you probably need to create them for your building.
With the Protractor tool, create an angled guide at the corner of your roof.
The nearby sidebar, “Pitched roofs can make you crazy,” points you to help with the Protractor.
Architects and builders often express angles as rise over run ratios. For example, a 4:12 (pronounced 4 in 12) roof slope rises 4 feet for every 12 feet it runs. A 1:12 slope is very shallow, and a 12:12 slope is very steep. When you are using the Protractor tool, SketchUp’s Measurements box understands angles expressed as ratios as well as those expressed in degrees. Typing 6:12 yields a slope of 6 in 12.
With the Line tool, draw a vertical edge from the midpoint of your roof to the angled guide you created in Step 2.
The point at which your edge and your guide meet is the height of your roof ridge.
Draw two edges from the top of your vertical line to the corners of your roof.
This creates two triangular faces.
Push/pull back your triangular gable.
If your gabled roof extends all the way to the other end of your building, push/pull it back that far. If your roof runs into another section of roof, as shown in Figure 4-35, extrude it back until it’s completely “buried.” The section “Sticking your roof together with Intersect Faces,” later in this chapter, has more information on how to make a complex roof.
Finish your eaves, fascia, soffit, and rake(s) however you want.
Gabled roofs have more details than we can cover, but Figure 4-36 shows a few common ones.
Believe it or not, building a hip roof is easier than building a gabled one. Hip roofs don’t have rakes, which makes them a lot less complicated to model. Follow these steps to find out for yourself:
Measure the distance from the midpoint of the gable to the corner of the roof.
Because hip roofs have pitches that are the same on all sides, you can use a simple trick to figure out where to locate the hip in your roof. It’s a lot easier than using the Protractor.
Draw edges from the point on the ridge you just located to the corners of your roof, as shown in Figure 4-37.
This does two things: It splits the sides of your roof into two faces each and creates a new face (which you can’t see yet) under the gabled end of your roof.
Erase the three edges that form the gabled end of your roof, revealing the “hipped” pitch underneath.
Neat, huh? Now all three faces of your roof are the same pitch — just the way they should be.
In general, the newer and more expensive a house is, the more roof slopes it has. Who knows why this is the case? Maybe folks think complex-roofed houses look more like French chateaus. Whether crazy roofs are a good thing isn’t relevant to this book, but they’re a pain in the, um, gutters to model.
Luckily, SketchUp has a relatively little-known feature that often helps when it comes to making roofs with lots of pitches: Intersect Faces. Here’s what you need to know about this terrific little tool:
When creating roofs, you can use Intersect Faces to combine a whole bunch of gables, hips, dormers, sheds, and so on into a single roof. Doing so is no cakewalk, and it requires a fair amount of planning, but it works great when nothing else will.
Figure 4-39 shows a complicated roof with several elements. Gabled roofs have been pushed/pulled into the main hip roof at all different heights, but edges don’t exist where all the different faces meet. In the steps that follow, use Intersect Faces to create the edges you want and then use the Eraser to clean up the mess:
Select the whole roof.
If you grouped your building and roof the way we recommend earlier in this chapter, here's a timesaving trick: Hide the group that contains the rest of your building and then draw a big selection box around the whole roof with the Select tool.
Choose Edit ⇒ Intersect Faces ⇒ With Selected.
This tells SketchUp to create edges everywhere faces intersect — that is, everywhere faces pass through each other without an edge.
With the Eraser, carefully delete the extra geometry on the inside of your roof, as shown in Figure 4-39.
Although this erasing can be a lot of work, it’s a whole lot easier than using the Line tool and SketchUp’s inference engine to figure out where complex roof details should go.