How wide is ice and water shield?
Short answer. Most ice and water shield comes in rolls about 36 inches (3 feet) wide, with lengths that vary by brand so that a roll covers roughly 100 to 225 square feet, with about 200 being common. Narrower self-adhered flashing tapes, a few inches to about a foot wide, are separate products used for windows and small flashing details.
Common roll sizes
- Width: about 36 inches is the standard for roof membranes.
- Length: commonly about 65 to 75 feet, which works out to roughly 195 to 225 square feet per roll. Some smaller rolls cover about one square, or 100 square feet.
- Coverage after laps: real coverage is less than the label because of side and end laps. Plan for that when ordering.
Why the width matters
- Valleys: a 36 inch sheet centered in a valley puts 18 inches on each side, a standard valley lining width.
- Eaves: where an eave ice barrier is required, it must reach 24 inches inside the exterior wall line. On a house with an overhang, one 3-foot row measured up the slope often falls short, so two rows are common.
- Walls and penetrations: crews cut the roll into strips and squares as needed.
Narrower products
Self-adhered flashing tapes come in narrow widths for windows, doors and small details. They are useful for sealing around penetrations or window openings but are not meant to line valleys or eaves. Check that any product used on a roof meets ASTM D1970 for steep roof underlayment.
Metric sizes
Some products are sold in metric widths, typically about one meter, which is close to 39 inches.
To figure how many rolls your roof needs, see how roofers measure a roof, and for where membrane belongs, ice and water shield in Georgia.