Your roof is constructed of several layers of materials. It’s not just the shingles that need to be in proper positions. Between your structure’s bare wood and shingles is an underlayment called roofing felt. This felt paper is designed to be a water-resistant layer in case moisture leaks between the shingles. During felt-paper installation, however, it’s critical to have dry materials. You cannot shingle over wet felt paper for several reasons. Learn more about this important underlayment so that your roof has a strong and long-lasting structure.

The Petroleum Issue

Felt paper isn’t exactly made of felt. It’s actually a petroleum product created into a flat sheet. You can’t shingle on wet felt paper (also referred to as tar paper) because oil and water don’t mix. If you leave the felt as a moist surface, the water will eventually penetrate it. The petroleum leaches out of the substrate, and it’s replaced by the water molecules. Your protective barrier is now compromised. You may not see the oil-and-water relationship at the beginning of an installation, but time will only create problems underneath the shingles covering wet felt paper.

Installation Hazards

Aside from concerns about the rooftop’s quality installation, the process of applying the materials is also compromised. Consider the average rooftop’s slope. It may be a gentle incline to the roof’s peak, but it’s a slope nonetheless. Stepping on the rooftop will be a challenge for either DIYers or professionals.

If you work with wet felt paper, it creates slippery conditions for the installers. In fact, the mixture of oil and water on the paper will create more problems than just the moisture itself.

Sheathing Damage

The plywood covering your structural beams is called the sheathing. It’s designed to offer a platform for the roofing materials. The sheathing cannot ward off the weathering elements like shingles can provide.

By installing wet felt paper directly onto the sheathing, you add moisture to the wood. No wood can withstand water over a long time period. It will break down over time. The installation might appear normal at first, but the sheathing will sag and break. Avoid two roof installations in a matter of a few years by using dry felt paper.

Microbe Growth

Water is a haven for microbes. They appreciate warm and moist areas. Install shingles over wet felt, and you have a perfect area for mold and mildew. The shingles prevent the moist felt from evaporating. Sunny days provide the warmth that microbes enjoy. You’ll eventually have growths across the entire rooftop.

These microbes break down your roofing materials. The damage may not seem significant, but the underlayment and sheathing will wither away. Leaks into the home will occur during the next rainstorm.

A Wrinkled Appearance

Lay your shingles on wet felt, and the installation won’t look professional. Shingles are constructed of a mixture of mounting edges and hanging tabs. It may seem like they’d splay out when they’re overlapped on the rooftop, but they should have a flat appearance when everything is nailed down.

Wet felt hidden under the shingles will warp and bend. This action forces the shingles upward. You’ll see a wavy appearance to the rooftop that’s not conducive to a protected area. Moisture can easily creep under these wrinkled materials.

Working Around Penetrations

All of your roofing materials should be dry because flashing and roofing tar work best in these conditions. Areas where penetrations reside, such as skylights or chimneys, must be protected from moisture penetration. Between the shingles and the penetration is roofing tar or metal flashing.

If installers must add the tar or flashing to wet materials, the transition won’t be smooth. There might be warps and bent sections that only allow water to infiltrate the rooftop. Let dry sections prevail before moving ahead with an installation.

Potential Leaks

Because wet felt will warp even under heavy-duty shingles, leaks into the home are inevitable. Your roof relies on the shingles to perform most of the protective work. There can be minute cracks and openings, however. The underlying felt should pick up the slack by stopping any further leaks into the roof. If the felt is warped, it cannot perform this backup job.

The compromised sheathing is now impacted again with moisture. Your attic will have moisture in it with this scenario. Over time, the leaks progressively worsen.

Drying it Off

Wet felt will happen on many rooftop projects. Be patient with the situation – you must let it dry out. Allow the sunlight to warm the rooftop if the felt is wet from morning dew. This fine film should evaporate relatively fast. Wet materials from a rainstorm, however, are probably saturated. It may take a few days for the materials to dry out completely. It’s worth the wait. Evaporation must take it course.

Crucial Overlapping

With your dry materials, don’t forget to overlap the felt paper during installation. For most sections, a two-inch overlap on the edges is sufficient. Any moisture that might escape the shingles won’t encounter an open edge on the felt paper. The overlapping edges force the water to shed down and into the gutters.

Successful overlapping requires dry felt. It’s difficult to maneuver wet materials, especially as you nail them down. The overlapping process is simply easier when you wait for dry conditions.

Roofing Maintenance

After a successful installation, you need to maintain the surface. Contacting the professionals for yearly inspections is the best way to protect your investment. They can replace any damaged shingles from natural, wear-and-tear issues. Nailing down loose materials will also prolong the surface’s lifespan.

Don’t allow anyone on the roof who doesn’t know how to walk on the surface. Unauthorized people can damage the surface with just a few footsteps. This damage can lead to expensive repairs so give the professionals a call for any rooftop walks.

There are many different types of felt paper available in the marketplace today. When the professionals quote your roofing project, ask about the products that might work with your structure. The key to a durable rooftop is the layers placed upon it.

For more information or to hire a local Lake Oswego roofing company, Give us a call: (503) 854-7200.

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