High Temp Ice and Water Shield Pros and Cons

Installing a reliable ice and water barrier is one of the most important steps when building or renovating a roof. In cold climates with heavy snow and ice, an effective barrier is crucial to prevent catastrophic leaks and water damage. High temp ice and water shields offer enhanced protection compared to standard products, but do come with some drawbacks.

What is High Temp Ice and Water Shield?

High temp ice and water shield is a membrane or underlayment designed to be installed directly onto the roof's decking material. It creates a watertight seal to prevent water ingress and guard against leaks caused by ice dams or wind-driven rain.

Standard ice and water barrier products are rated to withstand surface temperatures up to around 190degF. High temp shields are engineered with specialized polymer-modified asphalt or rubberized asphalt formulas to withstand high temperatures up to 260degF.

This increased thermal stability makes them ideal for use under metal roofing systems which can get extremely hot under the sun. It also provides protection in warmer southern climates prone to high summertime temperatures.

How High Temp Shields Form a Protective Barrier

High temp ice and water barriers utilize a thick, rubberized asphalt adhesive on one side that forms a strong bond with the roof deck. The topside is coated with granules, a polymer film, or a slip-resistant surface that allows the rest of the roofing system to be installed over it.

When installed correctly, the adhesive bottom creates a seamless seal that hugs the contours of the roof and seals around any fastener penetrations. This prevents water ingress while the tough top surface provides a durable walking surface and secondary waterproofing layer.

Advanced polymers blended into the asphalt allow it to maintain adhesion and pliability at both high summertime temperatures and freezing winter temps.

Benefits of High Temp Ice and Water Shield

There are several key benefits that make high temp ice and water shield a smart choice in many roofing applications:

• Superior performance in hot environments - High temperature resistance prevents the adhesive from softening and the seams from opening up under extreme heat.
• Better protection on metal roofs - The product won't degrade due to contact with hot metal roofing materials.
• Guards against leaks on low slope roofs - The enhanced adhesion prevents blow-offs and maintains a tight seal on low slope or flat roofs.
• Long lasting durability - Advanced polymers and rubberized asphalt hold up better over time.
• Resists cold weather hazards - Still provides effective ice dam and water infiltration protection.
• Versatility for all climates - Can be used as an all-climate solution instead of swapping products.

Optimal Use Cases

Based on its properties and performance strengths, high temp ice and water barrier offers optimal protection in the following scenarios:

• Under metal roofing systems like steel, copper, or aluminum where temperatures get very high.
• In southern, tropical, and generally hot climates where roof temps exceed 190degF.
• On commercial flat roofs and roof sections with poor ventilation.
• Asphalt shingle roofs with limited attic space and insulation.
• Homes using darker roofing colors which absorb more heat.

Ice Dam Prevention in Cold Climates

While designed for high heat resistance, high temp shield also provides reliable ice dam prevention in colder regions. The bonded membrane seals vulnerable areas like eaves, valleys, and roof transitions to prevent meltwater from infiltrating the sheathing.

It serves as a second line of defense if the primary roofing material gets damaged. The barrier maintains roof integrity and blocks water intrusion that could lead to catastrophic leakage, mold growth, and structural decays.

Potential Downsides to Consider

Despite the performance benefits, there are a few potential drawbacks to weigh with high temp ice and water shield:

• Higher cost - Expect to pay 20-30% more compared to standard underlayment.
• Trickier installation - The adhesive backing can make high temp products harder to work with.
• May not be necessary - For well ventilated asphalt shingle roofs in colder regions.
• Lower cold weather flexibility - The polymers can make the product more prone to cracking in frigid temps.

Added Material Costs

The main disadvantage of high temp ice and water shield is the added cost compared to standard shield products. The robust polymer-modified adhesives and special coatings add 20-30% to the price per square foot.

For a typical 25 square roof, this can equate to several hundred dollars in extra costs. However, defenders argue the enhanced leak protection and longevity justify the added investment on critical roof areas.

Homeowners should balance the risks of roof leaks and repairs against the higher initial material costs when selecting an ice barrier product.

Specialized Installation Requirements

High temp membranes have an aggressive adhesive that bonds tightly but can complicate proper installation:

• Surfaces must be perfectly clean and dry for adequate adhesion.
• Get full contact and seal around all penetrations and openings.
• Avoid trapping air pockets or lifting seams while applying.
• Use heavy rollers over the entire surface for full contact.
• Prime decks prior to application in cold weather.

While installation is straightforward for experienced roofers, do-it-yourselfers may struggle with getting a perfect seal. Consider hiring a professional roofer for best results.

When it May Not Be Necessary

While high temp shield offers excellent heat protection, it isn't always required. Here are some cases where a standard product may suffice:

• Cedar shake or asphalt shingle roofs with adequate attic ventilation and insulation.
• Northern climate homes with limited sun exposure on the roof.
• Areas where summer temperatures rarely exceed 90degF.
• For use only in valleys, eaves, and other trouble spots instead of full coverage.

Ventilation and Insulation Strategies

With proper attic ventilation and insulation, asphalt shingle roof temperatures can be moderated to not exceed standard shield ratings. Strategies include:

• Maximize ridge, soffit, and gable roof vents.
• Install vent chutes from eaves to ridge.
• Adequate blown-in insulation at rafter levels.
• Reflective radiant barriers under rafters.
• Circulating fans to vent hot air.

Maintaining temperatures below 190degF may allow standard shields to be used on well-designed roofs even in hotter climates.