What are the dimensions of ice and water shield: width, length and thickness?
Short answer. Standard roof membrane rolls are about 36 inches wide and roughly 33 to 75 feet long, covering about 100 to 225 square feet. Thickness is measured in mils: the ASTM D1970 standard has called for at least 40 mils, about 1 millimeter, and many products run thicker.
Width
About 36 inches is the standard for roofing membranes. Metric products are often about 1 meter wide, close to 39 inches. Narrow self-adhered flashing tapes, a few inches to about a foot wide, are separate products for small details.
Length and coverage
- About 75 feet: roughly 225 square feet.
- About 65 to 67 feet: roughly 200 square feet.
- About 33 to 36 feet: roughly 100 to 108 square feet.
Coverage is stated before laps; side laps of about 3 to 3.5 inches and 6 inch end laps reduce it.
Thickness
- Many standard smooth membranes are about 40 mils.
- Premium, high-temperature and granular-surfaced products are often thicker, commonly in the 50 to 60 mil range or more.
- Thicker is not automatically better; the temperature rating, adhesion and surface type matter for the job.
Weight
Standard rolls weigh roughly 50 to 65 pounds for 200 to 225 square feet, about a quarter pound per square foot.
Placement dimensions
- Valleys: one 36 inch sheet, about 18 inches up each side.
- Eaves, where required: to 24 inches inside the exterior wall line, usually two rows.
- Walls: several inches up the wall sheathing behind the flashing.
See ice and water shield in Georgia and how roofers measure a roof.