Ice and water shield is a stick down membrane with a gritty top. It cannot be removed from your roof unless you remove the wood with it. It is a water proof membrane that provides protection against ice back up and against shingle failure or shingle blow off. Ice and water shield such as Stormshield, Goldshield, Gripgard, Weathertex or Blueskin is placed at the eaves and goes around the bottom perimeter of your roof wherever there are eavestrough. The rolls come in three foot widths so generally estimates include three foot increments of this product.
How much ice and water shield should go on my roof? Should my whole roof be covered in ice and water shield since it's water proof? At Roofing for Less we have no standard answer. Every situation is different. The Ontario Building Code specifies there must be minimum three feet of ice and water shield. A lot depends on the size (width) of your soffit overhang, the pitch of your roof and your geographical region. If you have more than a two foot overhang you should have a 2nd row of ice and water shield meaning 6 feet. The overhang area is a cold zone and typically where ice starts to build up and possibly back up under the shingles so the wider it is the higher ice can creep up your roof under the shingles. If you have a shallow pitch it may be a good idea to have the entire area covered but this is done with caution as long as there is extra ventilation as having an entire roof covered in ice and water shield may actually cause condensation to build in the attic space if not ventilated properly. If you have a cottage in Orillia, Georgian Bay, Midland or Muskoka areas where snow and ice is significant and no one there in the winter months to clear the roof it may be a good idea to have more ice and water shield than the minimum.
Ice and water shield is not 100% protection. It is a waterproof membrane but then shingles are nailed on top essentially puncturing the membrane. If ice backs up under the shingles and onto the ice and water shield it can lift the nails causing a spot or small hole for water to leak in. Our Blueskin is the best product to address this problem as it forms a gel like barrier over the nail head not allowing it to pop up and make a hole. Blueskin is also used to waterproof basements. The best way to help waterproof your roof and keep leaks out is to maintain it properly, remove snow before it becomes ice and make sure there is sufficient insulation and adequate ventilation to prevent ice build up in the first place.
Finally ice and water shield is a necessary and mandatory component to receive any warranty from an installer or a shingle manufacturer so you should expect it to be included in every estimate you get.