• Ice dams occur when melting snow refreezes at unheated roof edges, trapping water behind ice ridges.
• This water backs up under shingles, causing leaks.
• Ice and water shields are rubberized asphalt sheets adhered to the roof deck.
• They create a waterproof barrier preventing leak damage from trapped melting water.
• Shields get installed along eaves, rake edges, valleys, dormers – any area prone to ice dams.

When snow melts and refreezes at the roof edge, it causes dams that trap water behind walls of ice, leading to back-up and leaks.

Trapped melting water has to go somewhere, so it penetrates under shingles and makes its way into attics, walls, insulation, etc. This water causes stains, rot, mold, and structural issues.

Ice dams place a lot of extra weight and stress on roof structures. The thaw/refreeze cycles also expand and contract shingles at connection points, wearing them out faster.

Long, pointed icicles that form from ice dams present falling/impalement hazards around entries or walkways below.

Water overflowing due to ice dams runs down exterior walls where it refreezes, cracking siding, painting, and trim materials over time.

Saturated insulation becomes far less effective, forcing homes to use more energy to maintain comfortable temperatures inside.

• Prevents Leaks: The waterproof membrane blocks water penetration from ice dams, saturated snow, and wind-driven rain from causing leaks and interior damage.
• Saves on Repairs: By preventing leak issues from the start, homeowners avoid the headaches and high costs of repairing rotted roof decking, mold removal, plaster/paint damage.
• Prolongs Roof Life: Limits freeze/thaw cycles and less weight and stress from ice buildup so your roof system lasts longer.
• Reduces Energy Costs: Stopping water saturation of attic insulation preserves optimal R-value for better temperature regulation inside. 
• Safety: Greatly reduces risks associated with long icicle formations along eaves and dangerous roof avalanches.
• Higher Resale Value: Ice water protection is now required by code in many areas, making it an attractive selling point for home buyers.
• Peace of Mind: Having robust waterproofing defense against ice dams means fewer winter roof worries and more comfortable peace of mind.

Eaves

The entire overhang area from the edge of the heated space to at least 24-36 inches inside the exterior wall line should have an ice barrier. This critical zone is where dams start.

Valleys

Centerline valleys channel large volumes of water and are prime areas for ice buildup and saturation. Shields help prevent infiltration.

Rakes

Like eaves, rake edges often overhang an unheated soffit area and are vulnerable to ice back up. Barrier coverage is advised. 

Roof Projections

Anywhere that roof planes intersect to create a crevice or lower area, like dormers, chimneys, vents should be wrapped in shields as water can saturate here.

Low-Slope Transitions

The seam where a sloped roof meets a porch, garage or dormer roof allows water pooling if not properly flashed and shielded.

Previous Leak Areas

Regardless the location, applying shield over any areas where past ice dams have formed or leaks originated adds an extra layer of protection.

• Thoroughly clean and dry the roof deck before applying the adhesive barrier.
• Ensure proper temperature for adhesion-most require over 20°F.
• Always start at the bottom edge and work horizontally up towards the peak.
• Overlap seams by at least 6 inches like shingles to prevent leaks.
• Use a hand roller or weighted roller to firmly press for full contact activation.
• Never stretch or pull shield taut-allow to lay flat to avoid contraction gaps.  
• Use caulk for sealing around roof details like pipes and vents.
• Cover with shingles or other roofing within 180 days.

• Inspect shields annually for damage during routine roof checks.
• Reapply seam caulk or membrane patches if needed over time.
• Prune overhanging trees to limit debris buildup and penetration hazards.
• Install gutter guards to prevent clogs from leaves that cause overflow.
• Improve attic ventilation to reduce heat and moisture that impact shields.
• Remove snow carefully with roof rakes in narrow strips to limit ice dams.
• Avoid unnecessary foot traffic over shields during roof snow removal.

• Mild Climates: If you live in an area with minimal snowfall and mild winters, the risk of ice dams forming is significantly lower. In this case, the cost of installing ice and water shield might not be justified by the minimal protection it offers.
• Steep Roofs: Ice and water shield installation can be more challenging and expensive on steeply pitched roofs. The steeper the angle, the more labor and materials are needed to properly adhere the membrane. In some cases, alternative solutions like proper attic ventilation and regular snow removal might be more cost-effective.
• Metal Roofs: Metal roofs naturally shed snow and ice efficiently due to their smooth surface and low coefficient of friction. Additionally, metal roofs are less susceptible to rot and water damage compared to asphalt shingle roofs. Therefore, ice and water shield might not be necessary for metal roofs, especially in mild climates.
• Existing Ice Dams: If your roof already has existing ice dams, installing ice and water shield directly over them might not be effective. The trapped water and ice can prevent the membrane from adhering properly, compromising its functionality. In such cases, it’s crucial to address the existing ice dams and ensure proper attic ventilation before considering ice and water shield installation.
• Budgetary Constraints: While the long-term savings from preventing ice dam damage can be significant, the upfront cost of installing ice and water shield can be a deterrent for some homeowners. Especially for older roofs nearing replacement, the additional cost might not be feasible. In such cases, prioritizing proper attic ventilation and regular snow removal can offer a more affordable alternative for winter protection.

Remember, consulting a qualified roofing professional is always recommended to assess your specific needs and determine whether ice and water shield is the right solution for your roof. They can also recommend alternative options for winter protection based on your climate, roof type, and budget.