Roof Structure | SelfCAD

About: Student at the Faculty of Civil Engineering at the Silesian University of Technology

Welcome to the roof structure modeling instructable.

With this tutorial we will step by step model a roof structure using SelfCAD - an online 3D modeling application.

Enjoy the course!

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Step 1: Preparation: Prepare Reference Images

To model a house we will need reference images. You can use any project or simply draw your own building. I used here my own drawings.

Step 2: Preparation: Create New Project

Launch SelfCAD editor and create new 3D project. SelfCAD's 1 unit is equal to 1 millimeter, but we will draw our building in centimeters. It means that in fact the model will be 10 times smaller in each dimension.

Now you should see the grid settings. I set Workplace Size to 2000 because 20 meters should be enough for my project. Segment Size means the spacing between grid lines and depends on your building's core centerlines. I entered here value 30.

Click Create button.

Step 3: Preparation: Add Images to the Scene

Click View, then Reference Image and add your images to the scene.

Step 4: Preparation: Set the Right Size and Position of Reference Images

Make the vertical image invisible by clicking the button with eye

Now, find two characteristic dimensions. It can be, for example, whole building or the measures between centers of cores. Add a cube to the scene and set its Width and Depth like these two dimensions.

Change size and position of the reference image so that the chosen dimensions match the dimensions of the cube. You should be in Orthographic Projection mode to do it precisely. Then you can delete the cube and move the image to mach core centerlines to the grid lines.

The second image you can match to the first one.

Step 5: Main Construction: Draw a Wall Plate

Go to the Front View.

Use Free Hand tool (Drawing → Free Hand or F+H). Choose Rectangle and in Plane Settings select Back/Front plane. Then go to Precision Settings, turn on Minimum Step Size and change its value to 1. In Height Settings you can set height value to 100 just for convenience but it's not necessary now.

Draw a square where wall plate should be. Apply the drawing. Use Scale (S) to make the object longer and Move (M) to put it in the right place.

Step 6: Main Construction: Copy the Wall Plate

Copy the wall plate and use Move to change second plate's position. Copy it again and place the third plate above the garage. Use Polygon Selection Mode to move the end of the last object to its place.

Step 7: Main Construction: Use 3D Sketch to Determine Middle of the Roof

This step is not necessary, but it can help us with drawing rafters.

Use 3D Sketch (Drawing → 3D Sketch). Connect the corresponding vertexes of the wall plates. Now draw a parallel line from the center of the line you have just drawn. You can enter the values of the second end manually. Look at the coordinates of the center. X and Z should stay the same. Now look at he reference image. The wall plates are on the level of 4.01 m and top of the roof 7.09 m, so it's 308 cm higher. It means that Y coordinate of also should be 308 cm (mm) higher.

Step 8: Main Construction: Draw a Rafter

Use a Rectangle tool to draw a rafter. Set it's height to 8. Rafter should be 20 cm wide. Remember that you can use erase when drawing to get the right shape.

Step 9: Main Construction: Copy the Rafter

Do you remember the X coordinate of the roof center? In my project it's 75.

Use Copy Offsets (Tools → Copy Offsets or C+O), select Pivot and enter coordinates. I used here 75, 0, 0 and applied my choice to get the second rafter. Now move the new rafter as in picture 2.

Step 10: Main Construction: Cut a Piece of the Rafter

Select both rafters and use Stitch & Scoop, Difference. As you can see my rafter wasn't drawn precisely and doesn't look good.

Use Stitch & Scoop again. And move copied rafter as in picture 2

Step 11: Main Construction: Draw Collar Ties

Use Rectangle and draw a collar tie. My collar ties are 14 cm high and 5 cm deep (height 5 in Rectangle tool). Move the object to the right place and copy it.

Step 12: Main Construction: Add Counter-battens

Add counter-battens. They are not parts of the main structure, but drawing them now should be easier.

Copy the first counter-batten and place it on the second rafter.

Step 13: Main Construction: Connect a Roof Truss Elements Into One Group

Select all 6 elements (without wall plates) and click Edit → Group or Ctrl+G to make one group

Step 14: Main Construction: Copy the Roof Truss

Move the roof truss to the extreme position. Use Copy Offsets and copy it by setting Z value in Position option depending on the dimensions in the reference image.

Step 15: Main Construction: Draw a Rafter Above the Garage

Now draw a rafter above the garage...

Step 16: Main Construction: Copy the Rafter

... and copy it like before.

Step 17: Main Construction: Add Battens

Battens, like counter-battens, are not structural elements. We can draw them now because it should be easier to cut holes for chimneys.

Use Rectangle tool to draw a rectangle 6x4. Use Scale to make it longer and Move to move it in Z dimension.

Now use Copy Offsets (Position). I decided to copy the battens with a 43 cm offset because I know that roof tiles like these exist. Copy the batten as many times as necessary. It's better to make too many copies, and later delete them, than vice versa.

The roof surface in inclined at an angle of 35 degrees. Select all battens and rotate them by 35 degrees.

Use Copy Offsets (Pivot) and copy all the battens as you did it with rafters. Use Scale to make last two battens shorter.

Add battens above the garage too.

Step 18: Chimneys: Cut a Hole for a Chimney

Draw a rectangle which will be subtracted from the construction. Use Scale to make it higher.

Isolate the objects we need (settings above the objects list). Use Copy Offset (Position 0,0,0) to copy rectangle 7 times (because we need 8 of them to subtract them from 8 objects).

Use Stitch & Scoop (Difference).

Step 19: Chimneys: Add Trimmers

Use Rectangle to draw a trimmer 8x14. Set its size and position. Copy the trimmer like in the picture 3.

Step 20: Chimneys: Repeat Last Two Steps With Second Chimney

Step 21: Roofing Over the Terrace: Draw a Ridge Purlin

Draw a ridge purlin 8x14.

Step 22: Roofing Over the Terrace: Cut a Gap for the Entrance 1

Draw a cube to subtract it from the structure. Copy it with Copy Offsets and use Stitch $ Scoop (Difference).

Step 23: Roofing Over the Terrace: Cut a Gap for the Entrance 2

We can shorten the counter-batten by drawing new rectangle, or copying a batten, increasing its scale and using Stitch & Scoop again.

Step 24: Roofing Over the Terrace: Add a Trimmer

Draw a trimmer 14x14

Step 25: Roofing Over the Terrace: Draw a Rafter

Draw a rafter and set its length and position. Use Polygon Selection Mode to lift one side

Step 26: Roofing Over the Terrace: Copy the Rafter

With Polygon Selection Mode still on, choose Move to see coordinates of the polygon.

Choose Copy Offsets (Pivot) and enter here X and Z coordinates of that polygon. Copy the rafter.

In next two steps you can see that this pair of rafters copied more times. I was too fast and had to delete them later. Don't worry and follow the course.

Step 27: Roofing Over the Terrace: Draw Purlins

Draw purlins 14x14.

Step 28: Roofing Over the Terrace: Draw Posts

Draw posts 14x14

Step 29: Roofing Over the Terrace: Complete the Rafters

Copy the purlins once and ridge purlin two times and subtract them from the rafters. Now you can copy the rafters.

Step 30: Roofing Over the Terrace: Complete the Posts

Draw two cubes under the posts and subtract them.

Step 31: Done!

Our wooden construction is ready.

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