The first layer that is laid on the roof, before the roofing panels, is an underlayment, which serves the purpose of separating the roof covering and the roof deck in order to prevent unevenness and protect the deck from damaging resins, weather and/or fasteners.
Until recent years, felt paper has been the standard underlayment choice that can avoid the roof covering from being damaged due to leaked sap from the building material made of wood. However, since most wood structures now are made from plywood or other wood alternatives, this is not a problem anymore.
Felt paper is packed with asphalt that is made from compounds that are not stable and thus, will disintegrate over time, leaving the underlayment fragile and more likely to attract moisture, which in turn, weakens the roof. Exposure to the sun’s UV rays and heat can accelerate this disintegration.
Since asphalt is a residual product of the crude oil refining process, an advancement in the refining techniques has resulted in the maximum amount of product being extracted from the crude resource and thus, the residue left is not enough to favor the making of asphalt. Lesser raw material present to develop the asphalt needed for a felt underlayment and preference towards a longer-lasting and cost-efficient solution has resulted in people turning to the synthetic alternative.
What is a Synthetic felt?
Also called a synthetic underlayment, this high-performance water-resistant layer is placed prior to the shingles on the roof decking and it absorbs asphalt from the roof covering. This synthetic felt outperforms the traditional felt underlayment and proves to be the better choice with more advantages.
Advantages of Synthetic felt:
- A synthetic felt is more lightweight, yet its strength is 20 times more as compared to the traditional felt paper.
- While it can be made to be permeable to moisture, a synthetic felt does not absorb moisture, and this helps it prevent fungal growth and crinkling.
- A woven scrim synthetic felt is easy to install and has a greater tear resistance
- It not only provides protection from the weather but also provides more strength and a longer UV exposure window.
- Some 100% recyclable options are also available
- Some synthetic felts are up to 25 degrees cooler than the traditional felt, which can help reduce the energy costs
- It guarantees longevity that surpasses the felt paper, particularly when it comes to areas with extreme weather conditions
While many of the advantages of a synthetic felt are related to the performance and quality, some of the secondary benefits ensure a smooth roofing installation with overall better quality. Its ability to lay smoothly and avoid wrinkling help reduce labor costs and ensure it does not tear.
Although a synthetic felt might be a better choice as compared to the traditional felt paper, it is important that the building code requirements and warranties of the manufacturer for the planned roof covering are followed before using it and the installation is done in accordance with the instructions provided by the manufacturer.