Replacing your roof can be a daunting thought. It can be difficult to decide on the best materials, evaluate your options, and determine the necessary steps. One of the primary decisions when replacing a roof is whether or not to remove existing shingles. It’s important to understand the impact that this decision can make on the success of your installation. This article dives into the pros and cons of removing existing shingles prior to metal roof installation.

Cost Impact

Removing Shingles Can Decrease Cost

The cost of removing existing shingles can be expensive. However, it can also lead to cost savings in the long run. The cost of removing shingles is typically lower than the cost of repairing any potential problems that can arise from leaving old shingles in place. In addition, leaving existing shingles in place can add extra weight to the roof, resulting in additional and possibly costly reinforcements to the structure.

Sales Tax and Insurance Liability

It is also important to note that many localities require the removal of existing shingles prior to the installation of a new roof, and in some cases, sales tax can be avoided. Additionally, insurance companies may require that shingles be removed prior to metal roof installation for liability reasons.

The Installation Process

Effect on Nailing Flanges and Moisture Protection

Leaving existing shingles in place may limit your fastening options due to the additional material, making it difficult to get a solid connection between the roof and the nailing flanges. In addition, this may also prevent a good seal between the roof and the deck, resulting in potential leakage.

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Ventilation, Overlaps and Seams

Ventilation is an essential part of any roof, and it can be difficult to achieve this when leaving the existing shingles in place due to the extra material. In addition, overlapping and sealing can be a challenge due to the extra material making it difficult for two sheets of metal to connect without actually overlapping as planed.


In conclusion, there are many considerations to take into account when deciding whether or not to remove existing shingles prior to metal roof installation. In many cases, the benefits of removing shingles outweigh the costs, such as potential cost savings in the long run, and avoiding potential insurance liabilities. Additionally, the benefits of removal may help to ensure correct installation, resulting in a better functioning and better protected roof.