Know The State and Local Codes

There are advantages and disadvantages to every roofing material. Asphalt shingles are more affordable but have a shorter lifespan. Clay tiles are extremely durable but heavy, requiring a reinforced roofing system. Metal offers stamina and ease of installment but at a higher cost.Metal Roofing over Asphalt Shingles Figuring out what is right for your current situation is the key, and our good residential roofing company will be there to help you decide. They are also part of ongoing maintenance and inspections, minimizing the chance for any costly major catastrophes. When remodeling or replacing a certain type of roofing material, part of the cost is tearing off what is already there. If a roof is damaged, removing the current system is a must…or is it? Can you install metal roofing over asphalt shingles? This post discusses using stone coated metal shingles over the top of asphalt shingles:
Can you avoid tearing off your old asphalt shingle roof by putting a steel roof over it? Maybe. Most codes now allow no more than two layers of roofing before requiring a complete tear-off. So, if your roof has two layers, it may require a complete tear-off, even though steel is lighter than asphalt. Codes vary, so call your local building department to know how to install metal roofing over shingles properly, code-wise.
Metal roof

sailormn34 / Pixabay

A steel roof is a lifetime investment, lasting 50 years or more if it’s a good one. Asphalt roofs typically last 20 to 30 years, depending on the installation and shingle quality. So, the investment might be worth it, but the range of choices makes shopping for a steel roofing system more complicated than you might think. If you want to get a metal roofing installation over asphalt, your best choice is to use a steel shingle system like the one shown instead of the more common (and more expensive) standing seam steel. In a standing seam roof, long, single panels run vertically all the way from the eave to the ridge. In contrast, steel shingles are small panels installed in horizontal rows much like other shingles. See the full post here:  Metal Roofing Installation:  How to Install Metal Roofing Over Shingles

Metal Roofing Panels

Does it work to leave asphalt shingles under long metal panels? It depends on the situation. Most codes allow only two layers of roofing before requiring a complete tear-off. You shouldn’t attach the metal directly to the OSB roofing deck. You need to add furring strips over the top of the shingles so you have something to attach the metal panels to. Other issues include venting the eaves and the ridge. Even though the audio is bad, this video demonstrates the process: As you can imagine, there are a lot of differing opinions on whether it is permissible to put metal over the top of other roofing materials. Some contractors feel that there is a problem with too much weight causing stress on the roof trusses and that condensation could be an issue. Others feel it saves the environment to preserve the old shingles and that they work as a layer of insulation making the home more energy efficient. On this forum from Angie’s List, this person has a strong opinion in favor of metal over asphalt shingles:
“There is absolutely no reason to remove a structurally sound asphalt roof to install a metal roof other than to add to cost. Tens of thousands of metal roofs have been done this way with no problems. Any contractor telling you otherwise without due cause with your particular roof should be avoided. They just want to inflate your bill. Find another contractor!” See the full discussion here:  Why Leave Shingles When Installing a Metal Roof?
There are always going to be contractors that are willing to take advantage of a situation. However, most Denver roofers are honest, hard-working individuals that want to do a good job and follow the rules.