When considering roofing materials, people generally give all their thought to the outer layer. However, you should also think about the roofing underlay. This is an additional layer placed beneath the roofing materials you see from outside, and it's a vital extra line of defence against damage and water penetration.
It used to be that all roofing underlay was made from felt—in fact, people have been using felt for that purpose for hundreds of years. Nowadays, we have another option: synthetic underlay. It's often a touch more expensive than felt, but it's well worth the cost.
Here are just four reasons why.
1. Synthetic Underlay Is Lighter
One of the key advantages of synthetic roofing underlay is that it is considerably lighter than felt underlay. You might not think that makes such a difference, but you should consider how much underlay is going to be used across your roof. The weight difference quickly adds up and places far more stress on the property, which puts it at increased risk of structural damage.
2. Synthetic Underlay Is Faster and Easier to Install
You want any roofing work to be completed as quickly and easily as possible. You'll save on labour, and you'll also avoid any problems associated with unexpected weather before the roof is finished. The lesser weight of synthetic underlay is one reason it's easier to install. It also stays safe and textured while felt tends to get slippery. Better yet, the fact that synthetic underlay rolls are generally longer means that doesn't take as long to cover the entire roof.
3. Synthetic Underlayer Tolerates Extreme Temperatures
Synthetic roofing underlay can tolerate both high and low temperatures; unfortunately, felt underlay can struggle with both. It doesn't tolerate long periods of high heat very well without buckling, and it often gets too stiff and starts trying to curl up during cold snaps. Synthetic underlays are significantly more stable.
4. Synthetic Underlay Is Much Tougher
In a perfect world, your roofing underlay would never need to meet the elements. In the real world, small gaps can form between roofing materials, cracks can develop, and individual shingles and tiles can drop off. When that happens, the underlay is exposed, which is essentially the end of the line for felt underlay. It will start to bubble and wrinkle almost immediately once exposed—if you don't call in a roofing contractor quickly, it can start to press out and push on intact external roofing materials. In contrast, synthetic roof underlays can last for weeks once exposed without presenting any problems.
Contact a roofing contractor for more information about roof underlays.