When creating a building structure in SketchUp the first thing you would do after importing the Autocad plans, is to start building walls. There are a couple of main methods which we explore in our SketchUp courses.
Firstly orbit around and zoom into the front wall area of the plans. The simplest method is now to trace over the edges with the Line tool (L), creating a face. We then switch to the Push/Pull tool (P), click on the face and pull it upwards in the blue axis to the height required > punch in 0.5 (m), for example, and hit Enter. Now choose the Select tool (the black arrow), triple-click on the wall object to select its associated edges and faces > then right-click > and choose Make Group. It’s good practice to create groups as you go. You could then create a new layer for the Exterior walls and move the new walls object to this layer.
Another method is using the Rectangle (R) tool to trace out the plan outline of the building on Layer 0, covering the whole rooms area of the floor plan. The order doesn’t matter. Then make the floorplan layer invisible. Then use the Eraser (E) tool to erase the inner lines. Now we have covered the full footprint area of the building. You could then Push/Pull this face upwards by 3m if creating a simple Massing Model.
However, if you want a more detailed model with wall thickness, use the Offset (F) tool to thicken the walls, using the CAD plan as a reference, or by first measuring the wall thickness with the Tape Measure tool (T), then Offset by punching in thickness, eg. 270mm for a double-brick wall. Now measure the wall height from the elevation drawing (eg. 3.2m) and Push/Pull walls upwards by that amount. Don’t forget to triple-click the walls with the Select tool > then right-click > Make Group. Move the object to its own layer and repeat the process for the Interior walls.
Many useful tips and techniques can be found at the SketchUp website. And see many examples of our own clients’ work on our Facebook page.
Other related SketchUp Blog Posts:

• SketchUp background
• SketchUp introduction
• SketchUp modeling
• SketchUp contours
• SketchUp workspace