Metal Roof Underlayment Requirements

This article series discusses roofing felt specifically addressing the roofing code or roofing manufacturer s requirements for use of an underlayment such as roofing felt tarpaper or other underlayment products beneath asphalt shingles and other.

Metal roof underlayment requirements.

10 roof protector underlayment roll best roof underlayment for metal roof. 11 plastic string reinforced poly sheeting best value roofing underlayment. At western states metal roofing we have been in the roofing industry for over 20 years and have encountered every type of scenario with both types of underlayment. It serves as a moisture barrier as well as a slip sheet.

This type of underlayment is critical to a quality roof installation. Becoming familiar with the metal roof underlayment options available can help you decide what s best for your commercial building. Power driven metal caps shall have a minimum thickness of 0 010 inch. Minimum thickness of the outside edge of plastic caps shall be 0 035 inch.

Is roofing felt required. How well roof underlayment performs will depend on which type you use. The first goal of roofing underlayment is to keep the roof deck dry before installation of the metal roofing material. Felt details for various roof slopes amp.

Synthetic roofing underlayment is to be laid horizontally parallel to eave with printed anti slip side up starting at the bottom of the lowest roof eave with a 1 5 underlayment overhang at the eave covering the pre installed eave drip edge. Overhang the roof rake edge 1 5 and cover the underlayment with a metal rake edge trim. Traditionally metal roofs have used standard 30 pound felt paper underlayment. We recommend a polypropylene scrim reinforced underlayment made up of multiple layers.

Choosing the right roof underlayment. For architectural metal roof panel systems a roof underlayment is required to help control water leakage through the roofing system during heavy rain storms or under snow melting conditions. We generally prefer the use of synthetic underlayment as it is more durable and will last longer. Metal caps shall have a thickness of at least 32 gage sheet metal.

13 1 frequently asked questions. Underlayment shall be attached using metal or plastic cap nails or cap staples with a nominal cap diameter of not less than 1 inch. Underlayment must also act as a secondary weather barrier in case the roof fails. Roofing underlayment roofing felt requirements.