How Rain Impacts Different Roofing Materials

Executive Summary

• Over time, substantial rainfall can degrade roofing materials by causing water absorption, structural stress, and increased biological growth.
• Certain roofing materials may react differently to moisture. For example, asphalt shingles are vulnerable to granule loss, while metal roofs may be prone to corrosion.
• Metal, tile, and synthetic options like Brava composite roofs typically offer better resistance against rain than asphalt and wood roofs, but they all require periodic upkeep to perform at their best.
• Having a roofing professional perform inspections, gutter cleanings, and other forms of preventive maintenance can significantly extend the life of a roof in rainy climates.

Understanding Rain’s Effects on Roofs

Most roofs are designed to handle periodic precipitation, especially when they are well-maintained. However, if your property is frequently exposed to moisture, your roofing materials may be negatively impacted, especially if you have not been keeping up with preventative maintenance.

Heavy rain’s effects may vary depending on the type of roof you have. Due to water absorption, some materials may experience swelling or degradation after consistent rainfall. Additionally, the added weight and accelerated runoff that accompany excessive rain can damage gutters, flashing, and roof valleys. Since moss, algae, and mold thrive in moist environments, homeowners may also notice the breakdown of roofing materials due to increased biological growth from persistent dampness.

The guide below covers the potential effects of rain on the most noteworthy roofing materials in Portland, Oregon, along with what roof maintenance services each type of roof requires to extend its longevity. Read through the following considerations to make informed decisions about maintenance and ensure you have the best roofing material for rain.

Asphalt Shingles

Due to their affordability and ease of installation, asphalt shingles are the most common roofing material throughout the greater Portland area. However, their low up-front costs are balanced out by their susceptibility to wear during heavy rain, which demands vigilant preventative maintenance.

Vulnerabilities

Some examples of rain-related vulnerabilities that asphalt shingles have are:

• Granule loss – Rainwater can gradually wash away protective mineral granules from shingle surfaces, exposing the asphalt to UV rays, which can accelerate the material’s aging and cracking.
• Water seepage – If shingles begin cracking, curling, or lifting, they may allow water to infiltrate under the shingle layers, encouraging issues like deck rot and leaks.

Maintenance Tips

Some important maintenance tips that people with asphalt shingles should follow are:

• Frequent roof inspections – After heavy storms, get your roof inspected for bald spots, curled shingles, or missing tabs, which are early signs of water damage.
• Clean gutters and downspouts – Clogged gutters can cause water stagnation, which can eventually back up under shingles, increasing the risk of premature failure.

Metal Roofing

Metal roofs are well regarded for their durability and water resistance. Still, because they have vulnerabilities to things like corrosion, these types of roofs are not maintenance-free, especially in the wet climates found in cities surrounding Portland.

Vulnerabilities

Some metal roofs can experience issues in wet weather, such as:

• Corrosion and rust – If protective coatings wear off, moisture is more likely to oxidize steel panels. Corrosion is prevalent around fasteners and overlaps.
• Noise amplification – Heavy rain can create louder impact sounds on metal surfaces, which may bother some inhabitants. However, with the installation of proper insulation, you may be able to dampen this effect.

Maintenance Tips

Any property owner with a metal roofing material can keep their roof in good shape by having a professional perform services like:

• Adding protective coatings – Adding galvanized or Kynar-painted finishes allows many homeowners to shield their metal roofs from corrosion. These finishes are especially important in areas with salt exposure or acidic rain.
• Clearing debris – Removing leaves, needles, and branches is a great way to prevent water from getting trapped against the metal, which would otherwise encourage rust spots.

For added protection and visual appeal, consider getting stone-coated metal roofs. 

Clay or Concrete Roofing

In warm, dry climates, clay and concrete tile roofs are known to offer exceptional longevity. However, in rainy regions, their lifespan depends heavily on factors like whether they have proper underlayment and drainage systems installed.

Vulnerabilities

Despite their durability, clay and concrete roofs are still prone to some rain-related issues, such as:

• Water absorption – Porous concrete tiles are known to absorb water, which can make them heavier and more susceptible to cracking from the freeze-thaw cycles that can occur during colder weather.
• Underlayment dependence – Tiles are usually not waterproof on their own. They require intact underlayment and flashing to avoid leaks in valleys and other susceptible areas.

Maintenance Tips

To extend the life of tile roofing, you should schedule professional roofing services, such as:

• Re-sealing and re-coating – Applying sealants or specialized coatings to concrete tiles can reduce porosity, which prevents saturation during rainfall.
• Inspecting flashing and valleys – Routinely checking mortar and metal flashing at hips, valleys, and ridges can ensure those areas are tight enough to avoid water intrusion.

Wood Shakes and Shingles

Cedar shake and other forms of wood roofing are popular because of their natural aesthetic, but without the proper precautions, wooden roofs can become vulnerable to Portland’s damp climate. With consistent care, homeowners can prevent issues like moisture exposure from compromising their roof’s performance.

Vulnerabilities

In rainy climates, wood shake and shingle roofing may be susceptible to concerns like:

• Swelling and warping – Wood fibers naturally expand when wet. After returning to standard size, dried roofing materials can reveal gaps that contribute to uneven rows and compromised water shedding.
• Rot and decay – Constant dampness is a common cause of fungal growth, which may manifest as mold development or wood rot. In turn, these conditions can rapidly shorten roof life.

Maintenance Tips

Some key ways to maintain wood roofing and prevent rain damage include:

• Applying water-repellent preservatives – By using penetrating treatments, professionals can seal roofs made from materials like wood, minimizing water absorption while allowing the material to breathe.
• Trimming overhanging branches – In most cases, improving airflow and sunlight exposure by cutting down overhanging branches helps wood roofing dry faster, ultimately reducing the risk of moss growth and wood rot.

Synthetic and Composite Roofs

High-quality synthetic and composite roofing products like Brava composite roof shingles are strategically engineered to mimic the appearance and function of natural materials while eliminating many of their weaknesses, including their susceptibility to water.

Vulnerabilities

When they are well taken care of, synthetic composite roofs made with reliable materials from Brava have no noteworthy rain-related vulnerabilities. In fact, these materials are intentionally designed to resist water absorption, making them resilient in wet conditions. When compared to common alternatives like asphalt shingles, they are less prone to UV degradation and the growth of moss or algae.

Maintenance Tips

Homeowners with synthetic and composite roofing should extend the life of their roof by:

• Scheduling periodic cleaning – Even synthetic, non-porous materials can benefit from occasional soft washing, which removes grime and pollen from a roof’s surface.
• Confirming warranty compliance – Keeping up with professional-led services allows many homeowners to meet their manufacturer maintenance guidelines, ensuring the coverage from their warranty remains valid.

Universal Preventive Measures and Best Practices

Regardless of roofing material, prioritizing preventive care is the best way to defend against rain-related damage. Some examples of universal ways Portland homeowners can be proactive are:

• Ensuring proper attic ventilation – Helps control the humidity beneath the roof deck, helping prevent condensation and mold growth even in rainy climates.
• Gutter and drainage maintenance – Cleaning gutters at least twice a year allows water to flow away from the roof and foundation more easily, reducing problems during rainfall.
• Regular professional inspections – Scheduling annual roof evaluations, especially after prolonged periods of rain, can promote early detection of issues, potentially saving you money in the long run.

Although the practices above can help you avoid future problems, if your roof has already suffered the effects of rain, promptly call a trusted roofing professional to schedule leak repairs or any other roof fixes you may need to avoid further damage.

Selecting the Right Material for Rainy Climates

Since Portland has an above-average annual rainfall of 36 inches, homeowners in the northwest region of Oregon need to choose the best roofing material for rain.

On one hand, asphalt shingles may be cost-effective, but they require frequent maintenance, especially during rainy seasons. Similarly, tile and wood demand attention to detail and periodic treatments, but they are generally considered more durable than asphalt shingles. 

Metal roofs are great for shedding water, but they should be coated in stone or given a corrosion-resistant finish for longevity. In the face of rain, synthetic roofs, like ones made with Brava composite, often deliver the longest lifespan with the least upkeep, making them an increasingly popular choice in Portland.

It is important to remember that even if you have chosen Brava composite, which is arguably the best roofing material for rain, you need to pair it with preventive maintenance to keep your roof performing efficiently in moist conditions.

Roof Life of Oregon Can Safeguard Your Roof From Rain

Rain may be inevitable in Portland, but roof damage doesn’t have to be if you get help from the professionals at Roof Life of Oregon. Our trusted company serves as a one-stop shop for Oregonians’ roof-related needs in rain or shine.

Our roofing specialists can help you by developing and carrying out a maintenance plan, performing professional cleanings, or selecting the best roofing material for rain when it is time for you to get a roof replacement. 

If you live near one of the areas we serve, you should schedule a free roof evaluation by contacting Roof Life of Oregon. We can offer expert guidance that keeps your home protected year-round.