How To Understand The Layers Of Your Roof: Underlayment and Ice & Water Shield

How To Understand The Layers Of Your Roof: Underlayment and Ice & Water Shield

Michigan’s winters bring their own beauty and fun, no doubt, but they can take a toll on your roof. The ice and water shield is one vital protection your roof probably has, but that you never see. You may not even know if you have such a layer on your roof. Your neighborhood residential roofer is a good resource for information about this important feature of your Grand Rapids-area home’s roof. 

Hidden Treasures

Beneath your beautiful shingle roof, several hidden layers provide additional protection to your home. These two layers are invisible when your total roof replacement project is complete. That’s unfortunate, because they deserve credit for defending your roof against nature’s attacks.

Underlayment is attached to the sheathing (those large, flat panels of plywood or oriented strand board). Underlayment is a water-resistant barrier used to seal around nail and staple holes to prevent water from seeping into the sheathing.

Yet underlayment cannot do everything on its own. Since the lower edge of your home’s roof is susceptible to snow and ice build-up, an additional layer of protection is put down. This is an ice and water shield, a tough, resilient, self-adhesive layer of a composite material. Unlike underlayment, the ice and water shield is waterproof and has no staples driven into it.

It is made from polymers (plastics) blended with bitumen (a waterproof binding agent made from petroleum). Most residential roofs are classified as steep-slope, meaning they have a pitch, or angle, which sheds water quickly. For these roofs, two rows of ice and water shield are usually adhered along the bottom six feet of a roof, with additional ice and water shield put down along the valleys (where two roof sections meet at a compound angle). Ice and water shield contributes to a long-lasting, winterproof roof

Three Types

Ice and water shield is available in three configurations:

  1. Sand-surface or granular — Slip-resistant, able to withstand fluctuating temperatures, hard-wearing, and self-sealing around roofing nails driven through it.
  2. Smooth surface — Often available for do-it-yourselfers at big-box home improvement stores, this material is slightly thicker than sand-surface. It is intended primarily for low-slope roofs but can also be used on steep-slope pitches.
  3. High temperature — While carrying a seemingly contradictory name, this ice and water shield has a high cotton-fiber or polyester-fiber content which allows the slate, tile, or metal roofing it’s under to expand and contract without binding to the ice and water shield.

For your Grand Rapids-area home, your local, reliable roofer will most likely recommend either of the first two types of ice and water shield. The type of ice and water shield is less important than the amount of material used and its proper installation. 

Huge Help

Some local municipal building codes may require two strips of ice and water shield for new construction or remodeling, but even if your local code does not need a total of six feet of protection at the eaves, discuss this with your roofer. By preventing water infiltration, ice and water shield can be a massive help to your roof.

In winter, the lower six feet or so of most steep-slope residential roofs take a tremendous beating. Through normal freeze-and-thaw cycles, snow on your Michigan home’s roof thaws near the roof surface. Water runs down on the roof, below the snowpack, and often freezes at the lower edge. If your gutters are already packed with snow and ice, this trapped water builds up as an ice dam.

When ice dams melt, all the water they contain sits directly over your eaves and can easily penetrate the underlayment and sheathing. Then, water infiltrates your attic, saturates insulation, and drips down onto the ceilings of your living space. Soon, mold and mildew set in. You may end up paying for emergency roof repair.

Ice and water shield can prevent all that damage. By forming a final barrier to meltwater, the ice and water shield prevents any water from flowing into the eaves. Your roof stays safe and dry. 

How Do You Know?

You cannot tell if you have an ice and water shield simply by looking at your home’s roof from the safety of the ground (never climb on your roof!). However, you can tell if you are probably lacking it if:

  • Your roof has a history of leaks, especially near the eaves.
  • Your energy bills spike in winter as your HVAC system fights humidity and cold air coming from infiltrating, icy water on the roof.
  • You ask your nearby residential roofing contractor to perform a site inspection. Your roofer can safely peek beneath your roofing surface — metal, tile, slate, or shingle — to detect the presence of the all-important ice and water shield.

Your Grand Rapids-area home will benefit from the extensive services available from Moore & Sons Roofing. Contact us today to learn all we can offer you, your family, and your home.

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