As this Hip Tip is of interest to allmost of the AutoCAD users here is the post in English.
Em Português veja aqui http://cad.blogs.com/cadptbr/2005/06/como_criar_um_t.html
Draw a closed polyline of the roof contour. (see picture)

Measures are in meters.
Put it in an isometric view.

Extrude the polyline as text in the picture

If you want a roof with an inclination of 15 degrees you must introduce in the taper angle 90 –15 = 75 .
Now we need to close the top of the roof. How!
Using the Solids Editing toolbar we will chose Offset Faces.
And then we will proceed as in the following picture

We can get one of these results…

Or to Offset faces only 1 meter and then the result will be this

Use your imagination to explore the potential of AutoCAD.
