Are you in the market for a new roof? If so, you will find that there are many options available in the roofing industry. These options can range from multiple variations of asphalt shingle types to many variations of metal panels.
One of the many questions a professional contractor is asked is, “can you install a metal roof over shingles?” The simple answer is yes. The dichotomous nature of installing metal over an existing tile roof requires many steps. We’ll look at these steps in more detail to help determine if retrofitting a metal roof over an existing asphalt shingle roof is an innovative idea.
There are several things to consider before deciding to install a metal panel roof over an existing asphalt shingle roof. The first thing to determine is whether the plywood or plank ceiling is safe and solid under the existing ceiling. Essentially, the roof deck must not be damaged by water ingress onto the old roof through any holes or other penetrations within the roof field. This will require some investigative work before installing the new metal roof.
It is strongly recommended to inspect all roof decks and structures from the penthouse side of the roof. One should look for dark spots, moldy spots, traces of water on the plywood or roof deck, and/or cracked or split beams. This must be done very carefully, as one mistake can damage your roofs or cause serious injury to oneself. After these things have been validated to be OK, then the next step is to start preparing the roof.
New 1×4 wood strips should be installed vertically and horizontally every 24 inches across the entire plane of the ceiling horizontally from bottom to top. It is highly recommended to use wood screws to attach the new 1 x 4 wood battens. After this is complete and you have a holistic approach to the entire roof, it is time to install the ceiling panels. Please note that all roof penetrations will need to be covered with flashing boots that will work with the metal panel chosen for the roof application.
In this step, the choice of metal panel is critical to the longevity of the life of the roof. There are metal panels that bolt to the surface of the metal that are nothing more than fancy barn tin. The problem with fancy barn tin panels is that the rubber grommets will eventually dry out and fail, thus creating a roof leak that can undermine the whole reason a metal roof was chosen to begin with.
A simple way to avoid face-bolted roofing material is to use a metal panel with hidden fasteners. These types of panels are called permanent metal seams. It is highly recommended when choosing a metal roof to think about longevity. Put succinctly, a hidden fastener panel will last the life of the metal with minimal chance of leaks in addition to failure of roof penetrations over time. This is normal for all roof types.
