When it comes to roof replacement, there is no one size fits all solution. For shingle roofs, there are four main types of replacement, but each can vary depending on the roof's condition.

Decking 

A decking replacement is not a requirement of every new roof. Decking is replaced only when the old plywood sheathing, which spans the roof trusses and provides the nailing surface for the shingles, has suffered major damages. Punctures, holes, and water damage are the types of problems that lead to a need for all new decking. 

A decking replacement is never done alone. It will be one aspect of a full roof replacement that involves replacing the shingles and the flashing on the roof. Sometimes, though, decking replacement can be partial if only a few pieces of the plywood sheathing have suffered damage.

Shingle Replacement

The most common type of roof replacement, the one most people are familiar with, is a standard shingle replacement. This is done when the shingles have aged out of usefulness but before major damages set in. This is also the most common type of replacement following minor storm damage.

The shingles and the underlayment felt or tar paper is torn off, and then new underlayment and shingles are installed. Often the same type of shingles is used, although it is sometimes possible to upgrade to different shingling materials like metal or tile. Flashing may be replaced if it is damaged or aging out of usefulness, but just as often the flashing may be left in place if it is in good repair. 

Roof Over

A roof over is essentially a shingle replacement, except the old shingles and underlayment are not removed. Instead, these are left in place to act as the underlayment for the new course of shingles. The benefits of getting a roof over are that it takes less time and it's less costly. 

A roof over is only an option if there is only one layer of shingles on the roof before installation begins. The overall roof must also be in decent shape, with no active leaks or major damages. 

Structural Replacement

Structural replacements aren't common unless the roof is exceptionally old or there have been major damages from a storm or other event. These types of roofing jobs involve repairing or replacing major structural components, such as roof trusses and ridge supports.

There are also more minor structural roofing jobs. For example, the eave structures may eventually need to be replaced, particularly if you have old wooden eaves that have begun to rot. 

Contact a roofing replacement service to find out what type of services you need.