Ice and Water Guard is a waterproofing material made to resist Ice Damming at the eave of a sloped roof under finish asphalt/composite shingles, wood shakes, or quarry slate roofing.
It is a membrane roofing underlayment that offers excellent leak protection for sloped roofs subject to ice damming or wind-driven rain. The standard product is a fiberglass mat material with adhesive on the bottom and a granulated asphalt surface on the top. Rolls are commonly sold in 100 or 200 square feet rolls, 50-55 mils thick, with a width of 36″ and a length of 33.3FT or 66.67FT, but some manufacturers sell them in 6″, 9″, 12″, and 18″ wide rolls, often around 75FT n length.
Ice dam material is placed right on the clean, smooth, and dry roof sheathing substrate, often followed by drip edge lapping overtop, and underlayment lapping over that. This creates a zig zag route that water must travel through these 3 materials before it can be exposed to the sheathing. Ice and water shield typically extends down 1-2″ vertically onto the fascia board, as long as a drip edge will be utilized. It is also installed on valleys which should be done prior to placement of eave rolls. Ice and water shield is also installed on rakes, ridges, hips, dormers, around skylights, cupolas, protrusions, etc.
For low slope roofs where added sheathing and moisture protection is often desired, it is not uncommon for Ice and Water Guard to be applied to the entire roof.
Overlapping sheets vertically at roll ends should be a minimum of 6″, and successive courses should typically be lapped at least 3″. Local building codes will determine how far up the eave ice and water shield should be applied, but 24″ past inside of the exterior wall is commonly sufficient. 30 days is a typical maximum amount of time for which underlayment can lay exposed to the elements, with some higher end products allowing up to 90 days. It should only be installed when temperatures are above 40 degrees as lower temperatures may lead to a lack of proper adhesion.
Other Ice and Water shield are available with a coated high-density cross laminated polyethylene film.
This particular material type is considered by some to be a premium product and in addition to being used on asphalt shingle roofs, it’s also commonly used under metal and standing seal metal roofs.
If ice and water shield happen to require installation on concrete, masonry, and fiberglass shingles a special primer will often be required for adhesion.