Should I tear off my existing shingle roof or should I install another layer of shingles over it?

This is a question that comes up very often when homeowners are trying to decide which is the most economical way to have a roof replaced.

Obviously the most economical way to have a new roof installed is to reroute over the existing shingles.

Disposal costs are minimal. The labor cost to remove the existing shingles is eliminated.

Underlayment costs may be eliminated. This will reduce material costs. The cost is associated with protection of the home during a tear off are greatly reduced. This includes the cost to have tarps available, plywood for protection of siding, windows, doors and landscaping, etc.

The labor cost to remove and replace areas flashings may be eliminated or greatly reduced.

Will the shingles on a re-roof last as long as a roof replacement?

No, generally you can expect up to a 30% decline in the life expectancy of shingles and stalled over existing shingles versus installed onto a roof deck. This will be especially true in warmer climates.

Can I get the same warranty on shingles installed over existing shingles as the warranty provided for shingles installed onto a roof deck?

What will help determine whether my shingle roof is a good candidate for a reroute?

Only one layer of shingles are now on the roof. There are no issues with roof leaks. The roof shingles appears to be relatively flat. There are no issues with ice damning.

Local building codes and ordinances do not prohibit reroofing. Most codes generally prohibit the installation of three layers of shingles.