Start at the Top With Permit and Check City Ordinances

Re-roofing a house, because of its affect on the structure, is a job that requires a building permit.

The permit should be acquired before purchasing roofing material, so that you don’t buy something not permitted in your neighborhood.

Many cities in Orange County, for instance, allow Class C roofs--a low fire safety classification--such as untreated wood shingles or shakes to be used in re-roofing a home.

But others use Class B as the minimum--equivalent to a wood roof treated with fire-retarding chemicals.

And in some areas where Class C roofs are permitted, the rules also prohibit re-roofing with a material that has a lower fire rating than the existing roof.

For new construction in many areas of the county, particularly in the hills, ordinances prohibit any use of wood.

At least one city, Lake Forest, also requires most roofs to be installed under more stringent building codes for high-wind applications.

In addition, while local building codes generally allow homeowners to do one re-roofing without stripping off the original roof covering, the weight of the two layers combined must be taken into account when a roofing material is being selected.

Composite shingles, metal tiles and other super lightweight products often can be applied over older composite or, sometimes, even wood shingles.

Clay or cement tiles, however, generally cannot be placed over any other covering because of weight considerations.