If you have shingles on your house and are thinking about investing in new metal roofing installation, you may be wondering if it is okay to install the metal over the shingles. The short answer is that it is usually okay, but there are some things to consider before you make a final decision.
Removing your existing shingles before completing your new metal roofing installation has these advantages and disadvantages:
- It allows your roofers to perform a thorough inspection of your roof and repair any rotted areas they find.
- Another thing your roofers might decide to do is increase the number of nails in your roof, providing a stronger roof.
- Removal will add time, labour cost and disposal cost to your project.
The best method of installing metal over shingles is to install 1 x 4 purlins across your roof. This allows you to add additional insulation if you would like. It also creates a solid, flat surface for your new roof since shingles are not flat (they overlap). Because the metal roof will expand and contract when the temperature changes, care must be taken to give it the room it needs to do this.
One advantage of leaving your shingles in place is that it reduces the waste that ends up in a landfill and it may save you money by reducing your labour costs. Still, it can be more complicated to install the metal roof over existing shingles, so it is a decision to think about carefully. Your professional roofing contractor will be able to look at your unique situation and roofing installation and give you the best advice about what to do.