The Top 5 Mistakes Made When Installing a Metal Roof

CalenderOctober 23, 2019

The Top 5 Mistakes Made When Installing a Metal Roof

Metal roofing has become one of the most popular roofing solutions in recent years due to its modern appearance and its longevity compared to a shingle roof. Not surprisingly, this popularity has resulted in a spike in demand for metal roof installations. While the extra customer volume may seem appealing, be sure you are thoroughly prepared for these installations to avoid headaches and one-star reviews in the future. Improper installation can significantly reduce the roof’s lifespan and even potentially damage an entire structure.

Below are the top 5 errors seen on metal roof installations, and how you can avoid making the same mistakes.

  1. Incorrect Measurements
  2. Fasteners
  3. Oil Canning
  4. Incorrect Sealant
  5. Improperly Attaching Flashing

Measuring Tapes for Measuring a Roof1. Incorrect Measurements

One of the easiest ways to delay or damage your project is by not measuring the roof correctly. Having the wrong measurements will lead to ordering panels that are the wrong size. Incorrect panels can result in an open edge of metal being exposed that will lead to rusting from not being protected from moisture. Use a roofing calculator to help with a more accurate measurement.

The same issue could arise from choosing the wrong panel type for your project. There is a large selection of metal roof panels in different shapes and profiles on the market. Be certain that the panels selected will have a weather tight fit on the roof to securely cover and protect the structure.

2. Fasteners

Improperly installed fasteners are one of the most common reasons for metal roof leaks. Fasteners should be screwed in with little resistance. They should not be under tightened nor over-tightened. If the washer is off center and visible, then the fasteners have been over-tightened. If the gaskets are not compressed firmly against the surface, then the fasteners are under tightened.

3. Oil Canning

Oil canning, sometimes referred to as “stress wrinkling”, is the visible waviness or rippling in the flat areas of metal roofing as shown below. While this can be a result of fasteners being tightened incorrectly, it can also result from clips not being placed properly. Make sure the clips fit into a panel seam without forcing the vertical seam out of plane.

Metal Roofing Oil Canning

4. Incorrect Sealant

Sealants are used to keep out elements that could compromise the roof, such as water or dirt. When not applied correctly, the roof could be prone to leaks. It is also important to use sealant specifically made for metal roofing. Other types of caulking may not adhere to the paint on the panels. The sealant must also be flexible enough that it can expand with the metal without breaking its seal.

5. Improperly Attaching Flashing

Flashing keeps water from entering a structure at a roof penetration or joint. When it is not attached correctly, moisture is able to get in, resulting in a leak. Any area that has penetrates into the roof, such as ventilation ducts, chimneys, and skylights, should have flashing installed surrounding it.

Make sure the correct flashing is used, along with the correct size, so that the area is completely covered. Flashing seams should be properly sealed to allow water to flow on top of the material and prevent it from going underneath the roofing.

Additional Considerations

Placing Over Existing Roof

A customer that is budget conscious may request that the new roof be placed over the existing roof to avoid the extra expense of the old roof being torn off first.

Although a metal roof can technically be installed over an existing shingle roof, you should consider if it’s worth the risk. If the original roof has any issues, such as rotting or improper underlayments, it could compromise the lifespan of the new roof.

If the original roof had leaks, the decking would have gotten wet and may be weak with soft spots. Weak decking might not be able to handle the weight of a new metal roof on top of the existing roof, resulting in a major problem for the homeowner.

Check the current roof condition and explain the potential hazards of not tearing off the original roof to your customer. Although it will cost the customer more upfront to tear off the old roof, the investment will pay off in the long term to start fresh with a brand new roof.

Metal Roof Installation Supplies

Avoiding these common errors along with taking your time, paying attention to detail, and using quality products will help you in having a successful metal roof installation.

You likely need to stock up on some additional supplies for your next installation. We’ve listed the accessories you’ll need to complete the job below:

  • Metal Roofing Panels: Lightweight and durable panels for commercial and residential use.
  • Underlayment: Moisture protective covering systems.
  • Foam Closures: Prevents elements from collecting under the ridge cap and panels.
  • Trim and Flashing: Prevents the passage of water into a structure.
  • Pipe Flashing: Seals tightly around small ventilation pipes.
  • Butyl/ Sealant Tape: Sealing of metal panels, roof vents and pipe flashing.
  • Fasteners: Mechanical securement devices used to secure various components of a roof assembly.




Lauren Risotto

About The Author

Lauren is the Content Manager at Western States Metal Roofing and provides insight on content creation and product promotions.