by United Roofing MN | Oct 4, 2011
Underlayment Requirements For Minneapolis Minnesota Underlayment is a material placed on the roof sheathing before installing shingles. It is usually a thin, black, paper-like material, often referred to as roofing felt. It comes in a roll and is usually 36” wide. It also comes in different thicknesses or weights. The minimum acceptable underlayment is 15# roofing felt. Underlayment may also be a self-adhering, rubber-like material. This type of underlayment is most often used at the roof edge and in valleys to help minimize damage from ice-dams. Many shingle manufacturers recommend their own type of self-adhering underlayment and where it should be used. Some local building codes and UL standards require that a shingle underlayment be installed. Underlayment shall comply with IRC Section 905.2.3 and its application shall be according to IRC Sections R905.2.7 and R905.2.7.1. Minnesota’s climate is considered severe with respect to underlayment requirements. An ice barrier is required and shall be installed as follows: • The ice barrier shall consist of two layers of underlayment (15# roofing felt) cemented together or a single layer of a self-adhering sheet. Whichever product is used, it must be installed parallel to and extend from the eave edge to a point at least 24 inches inside the exterior wall line. • After installation of the ice barrier, install remaining underlayment as follows: For roof slopes of 2 units vertical in 12 units horizontal (2:12) up to 4 units vertical in 12 units horizontal (4:12), underlayment shall be two layers of 15# felt. Starting at the ice barrier, install the first course of 36 inch wide underlayment lapping the ice barrier a...
by United Roofing MN | Sep 22, 2011
Roofing Contractors Minneapolis & St Paul MN All roofing systems are made of a number of different components: roof sheathing, underlayment, roofing material, roof intersections, flashing details and ventilation. Each of these systems must be installed correctly for the system to work as designed. Roof underlayment acts as water barrier installed underneath the roofing system. Essentially, it is a roof underneath the roof. It protects your roof from condensation that may form underneath the metal due to the differences in temperatures in the attic and outside. More Information On Felt Roofing Underlayment One of the most common mistakes being made today in the installation of asphalt shingles on new or re-roofing work is the practice of not using felt underlayment. Many thousands of new homes do not have felt beneath the shingles. This is a HUGE mistake! Remember, shingles rely on gravity to keep water from entering your house. It is very possible for wind driven rain to get underneath your shingles or to enter along valleys (especially when the valley shingles have been improperly trimmed!) Without felt Underlayment, you have no hope of stopping a leak. With felt, there is a possibility that the water will travel down the felt and not enter your house. Many asphalt shingles that are installed on residential roofs carry a Class A fire rating. This rating is given to the shingles by independent laboratories. The ratings are granted only when the shingles are installed as they were tested in laboratory conditions. The shingles are tested with felt in place under the shingles. As such, if felt is deleted on your job, the shingles...
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