Check with local code official for re-roofing restrictions and landfill disposal should existing roofing need to be removed.

Re-roofing over most existing fiberglass or asphalt shingles can be done with Centurydrain.  The shingles must be smooth (without curling, blisters, etc...) and 30 lb felt or other acceptable underlayment is to be used over the shingle.

Existing roofs of multiple layer fiberglass or asphalt shingles and various other types of shingles should be removed or framing strips applied over the existing membrane for support of Centurydrain.