Proper Roofing Underlayment Installation

With laminated shingles place four to six quarter sized dots spaced evenly about one inch above the bottom of the overlapping shingle.

Proper roofing underlayment installation. Roof underlayment prevents the roof deck from being exposed to the elements before or while the roofing material is being installed. It starts with installing solid decking usually plywood or oriented strand board but that is not waterproof. There is a direct connection between membrane performance and proper application. Center a minimum 610 mm 24 wide minimum 28 gauge pre finished galvanized metal valley liner in the valley and fasten with only enough nails to hold it in place nailing at the edges only.

Roofing underlayment roofing felt requirements. It must be covered with waterproofing membrane usually roof felt also. Overlap each metal piece by at least 150 mm 6 and use asphalt plastic cement under each section of overlap. 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. Underlayment in high wind areas i e where wind speeds are 110 mph or greater must be secured with corrosion resistant fasteners spaced no more than 36 inches apart. 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. Roof slopes greater than 4 12 require only one layer of underlayment.

Ideally the roof covering material would be installed as soon as possible but in reality the roof may be protected by only the underlayment for days weeks or sometimes months. For three tab shingles place two quarter size spots of plastic roof cement under the lower corners of each tab as shown in figure 2 7.