Underlayment is a vital part of a roof’s structure, something that can protect the roof deck in the event that the roofing itself fails or if water should seep beneath shingles. But can the underlayment itself fail? It can if it has been damaged—and here are some of the things that can damage underlayment, which could lead to problems over the lifecycle of the roof.
- Shoddy Installation
When contractors install underlayment, care must be taken to make sure that it isn’t torn, wrinkled or otherwise damaged. Additionally, it should be installed with manufacturer-approved fasteners so that the underlayment performs as it should without voiding the warranty. Poor installation can lead to problems, so make sure that contractors are up to the job.
- Loss of Volatile Organic Compounds
One of the problems with asphalt underlayment is that it contains volatile organic compounds (VOCs) that initially add to its toughness. But these compounds degrade and evaporate over time—sometimes relatively quickly, particularly in hot weather. When that happens, the underlayment loses durability, becomes more moisture absorbent, and thus, much more prone to failure.
- Poor Quality Underlayment
This is particularly true with low end asphalt roofing felt. Poor quality underlayments are much more likely to degrade quickly and fail long before the roof itself would normally need to be replaced. Additionally, while low quality underlayment might be attractive from a cost standpoint, they’re often an unwise idea because they can lead to water seeping through the underlayment, damaging the roof deck below. In other words, saving money on a cheap alternative adds up costs later on.
- Exposure to UV Radiation
This is another way in which underlayment can be damaged—and all types of underlayment have different UV tolerances. Asphalt felt, for example, deteriorates quickly under UV exposure, which means that when exposed, it needs to be covered immediately. Synthetics perform better in this regard, but still, it’s best not to leave them exposed unnecessarily. Products like Plystik Plus, however, can give you up to 180 days of UV exposure should the need arise.
- Exposure to Moisture
UV exposure isn’t the only danger to underlayment. Traditional roofing felt also shouldn’t be left exposed to moisture as it may leak. Again, synthetics tend to perform better, particularly peel and stick underlayments designed to provide a good seal on the roof deck.
- Wild Animals
Wild animals aren’t something we normally stop to consider where roofing is concerned, but it is true that they can damage underlayment! Raccoons or squirrels can rip shingles and underlayment both if they want to get inside—and that’s why it’s important to keep trees trimmed well away from homes, to keep wild animals from damaging a roof.
Above, we talked about how heat can lead to loss of VOCs, which reduces the durability of asphalt underlayment. Expansion and contraction can do some damage, too, particularly around fasteners. In cold weather, underlayment can become more brittle, especially traditional roofing felt. That means footfalls or other impacts can cause damage. Here, too, synthetics tend to perform better because they are designed to be temperature resistant and they have higher tear strength than traditional felt.
Keep these things in mind when choosing underlayment for your next roofing project. Some issues can be avoided by using good installation practices and following manufacturer instructions—but it’s also a wise idea to choose underlayments that suit installation needs, the climate, and the roofing materials you will be using.