As a protective layer positioned between the roof deck and the external roofing material, such as shingles or tiles, underlayment is an essential part of any roofing system. Historically, the most common option has been felt underlayment, which is composed of fiberglass or paper that has been wet with asphalt. Its main purpose is to offer an extra line of defence against water penetration, particularly in the event of intense rain or ice accumulation. Newer materials like ice and water shield, which provide improved performance, have been developed by technological advancements in roofing. Understanding the distinctions between ice and water shield vs felt allows homeowners and contractors to make better decisions for the lifespan and waterproofing of their roofs.
Superior Waterproofing Properties of Ice and Water Shield
Ice and Water Shield is a self-sticking membrane that adheres to the roof deck directly. It is composed of rubberized asphalt and has a sticky backing. Ice and water shield aggressively seals around nails and fasteners, preventing water from leaking through even in the case that shingles are broken or moved, in contrast to felt underlayment, which just serves as a passive barrier. Because of its adhesive properties, it works particularly well in places where water can readily seep in and produce leaks, such as eaves, roof valleys, and ice dams. In colder climates, the rubberized membrane also maintains its flexibility, preventing the felt underlayment from shifting or cracking.
Enhanced Protection against Ice Dams and Wind-Driven Rain
When melting snow refreezes at the roof’s edge, ice dams confine water beneath shingles. This stored water backing up and piercing the roof deck may cause leaks and internal water damage. Ice and Water Shield protects vulnerable regions by preventing water from soaking through roofing materials. In windy places, this membrane resists wind-driven rain better than ordinary felt, reducing storm water penetration.
Durability and Longevity Benefits
Ice and water shield outlasts felt underlayment. Felt may degrade with time, especially in rainy places or during installation delays. It tears easily and may not seal around nails or fasteners. The rubberized ice and water barrier stays in place and doesn’t rip even in bad weather. Durability reduces maintenance, upkeep, and roof system replacement, making it a cost-effective solution despite its higher original cost.
When to Choose Ice and Water Shield over Felt
Even though felt underlayment is cost-effective for many roofing projects, ice and water protection is recommended in areas with heavy snowfall, ice dams, or frequent storms. In cold climates, building codes require water and ice protection in valleys and eaves. For homes seeking maximum waterproofing protection and peace of mind, an ice and water shield can extend roof life and avoid costly water damage. An experienced roofer can help choose the best underlayment for local weather and roof design.
