How to Install a Metal Roof Over Asphalt Shingles
You may have heard that how to install metal roofing over asphalt shingles is a tricky and lengthy process. The fact is that it really isn’t any different than doing it over tar or gravel roofing. You can’t just slap the shingles on there and hope for the best. It takes some planning, testing, and experience to know exactly which product is best for your home. It’s a bit like choosing paint, shoes, or even hair dressers.
One thing you need to know right off the bat is that not all metal roofs are created equal. Most asphalt shingles are manufactured using a high-performance material known as asphalt tar. Unfortunately, this low-density material doesn’t have the strength or durability to last a long while. The layer of asphalt underneath can easily be stripped away in the course of a windstorm. Asphalt shingles are meant to be lightweight and durable, but this low-density material just isn’t quite strong enough to withstand the beating of a hurricane.
There are two main types of metal roof underlayment that you can choose for your project. One type is the rolled row system. This is made up of a series of overlapping hexagonal boxes and is used in commercial and residential roofs alike. They are easy to install and are very long-lasting. Although they are slightly more expensive, they are also better at resisting heat, which makes them a good choice for hot climates.
The second type of underlayment, you may be more familiar with is the pressure molded, or blown in product. These are usually sold in rolls and can either be used on their own or as a joint product between two pieces of metal roofing. They are more expensive than shingles, and because there is no asphalt layer underneath, you may find that you need to strip off the extra metal to make room for the joints. However, these roofs provide the best strength-to-weight ratio.
Before you begin installing a metal roof over asphalt system, you will need to inspect your roof to see what kind of existing roofing you have. If you have an asphalt layer, your roof probably requires some form of repair or replacement. In some cases, you can use roofing paper to hide any gaps or seams the product creates, but in other cases, you may need to cut out portions of the existing roof. Keep in mind that in most cases, you will need to remove at least part of the existing roof, so it is a good idea to consult a local roofer about your options before rushing into a major project.
The installation process typically takes about three to four days from start to finish, depending on the type of roof you have. Metal roofing over asphalt shingles usually only take a day or two, and there is no additional drying time required. Before you begin removing the existing roofing, be sure to secure all loose parts with roofing screws or nails. To ensure maximum effectiveness, you should follow all manufacturer’s instructions for the specific material you use and perform all actions in careful, cautious fashion. Following these basic steps should help you learn how to install a metal roof over asphalt roofs successfully.