If you want to install a metal roof over shingles here in Texas, you must avoid these 4 critical mistakes: Bad decking, no underlayment or lath, improper roof trim, and skimping on quality.
Mistake #1: Not Checking Your Roof Deck
Roof decking is the plywood underneath your existing shingle roof. Think of roof decking as the foundation of your roof.
If the foundation isn’t solid, any roofing you attach to the decking will tend to fail over time.
That’s why it's important to check your roof decking before you install a new metal roof.
If your decking has moisture damage below the shingles, your roof may look fine on the outside, but cause your new metal roof to fail over time.
Metal panels are attached to your roof with screws. If your decking is rotting, the screws that attach your new metal roof will get loose, creating roof leaks.
Before installing a new metal roof over shingles, replace any damaged decking so that your new roof lasts for a very long time.
Mistake #2: Not Installing Lath or Underlayment
You never want to install a metal roof directly over existing shingles without some type of separation.
We have two approaches that we use, depending on what your current shingle roof looks like. If your current roof deck is in great condition, and your shingles lay flat, we’ll attach an underlayment to your roof before installing the metal panels.
This keeps your new metal roof from any direct contact with the shingles.
If your existing roof has decking that’s questionable, or shingles that don’t lay flat, we’ll use our lath system.
Our lath system consists of furring strips that are nailed to the roof at regular intervals. When we install the new metal panels, the screws will anchor into both the furring strip and the roof decking, creating a solid base for each screw.
Mistake #3: Not Installing the Proper Metal Roof Trim
Proper metal roof trim is essential for a long-lasting metal roof. Failing to properly install rake trim (the trim on the gable end of your roof) can allow wind to get under the edge of the metal panel. The wind can create a vibrating effect, working the metal roof up and down until the screws holding down the panel start to loosen. Proper metal roof trim eliminates this issue.
Secondly, the proper roof trim blocks rain from getting underneath the edge of the metal roof panels, even in harsh weather. And blocking rain is your roof’s number one job!
Thirdly, without the proper trim your new roof will look unprofessional and incomplete. In short, your roof will look unfinished, because it is. With all the proper trims, your new metal roof will look sharp, increasing the curb appeal of your home.
Mistake #4: Cutting Corners on Metal Quality or Workmanship
Your roof is like the umbrella that protects your entire home. If you use poor quality metal roof panels, or an inexperienced roofing crew, you can soon have leaks that cause damage to the interior of your home.
The risks of a cheap metal roof far outweigh the temporary cost savings. When it comes to home renovation, anything worth doing is worth doing right!
Is it still a good idea to install a new metal roof over a shingle roof?
Yes! Installed properly, metal roofs are extremely durable, even in the face of the harsh weather we experience here in Texas.
That’s why we can offer a manufacturer’s lifetime warranty. Installed correctly, a metal roof will typically be the last roof you’ll ever need for your home.
Learn how a new metal roof can actually pay for itself here.