Metal roofing uses a lot of metals, and so does the underlayment that is laid below the roof. The purpose of the underlayment as well as your needs as the occupant determine what kind of underlayment material you will choose. Today underlayment materials range from simple synthetic products to organic materials for those who are going green with their house construction. Also common are rubber and fiberglass roof underlayments. If you are planning to change your roof, now is the best time to get acquainted with the various materials that can be used for its underlayment.
Asphalt has been the material of choice for underlayments. It is also called as paper felt or builder’s felt. The way of converting it into a sheet is to impregnate a paper sheet with asphalt, which makes the substance more tenacious to perils such as fire. The asphalt sheet is classified for its thickness, referred to in construction parlance as #15 or #30. However, though common, these materials are slowly phasing out, mainly because of their tendency to capture moisture and make the interiors warmer in summer. Also, though they can be put up quite easily, they have a tendency to get ripped.
Polypropylene is commonly used. Some other polymers also may be used. There is no precise parameter for their composition yet, and different manufacturers use different materials in different compositions. The prices also vary. A lot of people are veering toward using these materials mainly because of their high durability and the host of features that they come with—they are branded as fire-resistant, heat-resistant, tear-resistant and so on. They are also considered safe for the people who put up the roofs because of their low slipperiness.
Peel and Stick Underlayments
As their name suggests, these are the most convenient to install. They contain organic substances and are generally made heavier. Due to their thickness, they don’t tear as easily. They have an adhesive material to fix them in position. Some of these may not be entirely organic; they might be fused with asphalt to give them a stronger feel. Some of them are impregnated with granular materials which give them a second base for protection. Such underlayment sheets can keep water out in a much more efficient manner than single sheets.
Mineral Surface Underlayments
These are granular sheets which are manufactured with a variety of minerals in their base. These minerals are added for specific reasons, such as to make them fire-resistant, or to make them less slippery, or to make the sheets stronger. These are the most expensive type of underlayment sheets and are the most suited for metal roofing because of their specific qualities.
When looking for a metal roofing underlayment, you need to look at these qualities, and you also need to look at how easy or difficult it would be to install them. Some of the more modern sheets are designed in a DIY manner, which come with a complete set of instructions on how to install them.