If the official version is out of your budget, there are excellent free or "freemium" extensions available through the SketchUp Extension Warehouse Sketchucation Roof (by TIG):
A classic, robust ruby script available on Sketchucation that generates complex roof shapes. 1001bit Tools (Free Version): instant roof pro plugin free download
for free is tempting, I must strongly advise against downloading "cracked" or "nulled" versions. These files are often bundled with that can compromise your computer and your design files. If the official version is out of your
While the idea of getting a premium plugin like Instant Roof Pro instant roof pro plugin free download
