Replacing Roof Shingles

A recent storm blew some roof shingles off our friend's house in Denver. To avoid water damage those shingles need to be replaced before the next storm. This isn't an expensive or time-consuming project but it can be dangerous as he needs to balance at the edge of his two-story roof to replace some of these shingles. The following sites have step-by-step instructions for shingle replacement as well as precautions when working up high.

Replacing Asphalt Shingles [Easy2DIY]
Replacing Individual Asphalt Roof Shingles [Hammerzone]
Repairing and Replacing Asphalt Shingle Roofs [Oldhouseweb]