As metal, tile, slate and other premium roofing material markets grow in the U.S., self-adhered (SA) underlayments are playing a critical role in roof assembly. Advancements in adhesion and increased confidence in walkability make it a product a lot of roofers are coming to rely on. This is because products like PlyStik Plus and PlyStik SA-250 create a durable watertight seal that are fairly simple to install.
Looking for ways to get the job done perfectly when you’re next installing SA? Here are some tips to help you out!
1. Always Follow Manufacturer Installation Instructions
Most peel and stick/self-adhered (SA) roof underlayment products come with great warranties—and those warranties can be voided if you do something that goes against the way these underlayments are supposed to be installed. Read the instructions and warranty information carefully to make sure that you’re installing over an approved substrate, covering the right products, using the right fasteners (if needed), and that you’re avoiding exposure that goes beyond warranty limits.
For example, you can see precautions and instructions by checking the PlyStik Plus datasheet or the PlyStik SA-250 datasheet, which stipulates that this product should be covered by a primary roofing product within 180 days and that it is not intended for indefinite exposure.
2. Use the Right Sealants, Primers, and Caulk, Too
Regarding choosing the right products for the job, be sure to also check with the manufacturer about the types of caulk and sealant you can use with the underlayment, too. Some include chemicals that may degrade certain types of underlayment over time, so you’ll want to avoid these.
3. Be Extra Careful with Ventilation
Most self-adhered roof underlayment products provide not only a moisture barrier but a vapor barrier, too. This can be problematic without proper ventilation since condensation that forms inside the structure needs a way out in order to prevent rot and other types of damage. Make sure to check that you have enough intake and exhaust ventilation.
4. It’s All About the Sticky Part
Anything that interferes with adhesion will cause poor application when you’re installing self-adhered underlayments. Substrate material (most commonly OSB) that is wet, flaking, old paint that is peeling, dirt—you name it, these are all things that can cause failure in the adhesion. Before you apply, make sure the deck is clean. If need be, apply a coat of primer to the substrate before you put the underlayment down to ensure maximum adhesion.
5. Getting a Good Seal
You’ve cleaned and primed (if necessary) the roof deck, and you’ve rolled out the underlayment. What else can you do to ensure that the underlayment adheres well? Use a weighted roller as you install it. Apply pressure with an 80-pound roller, especially in areas where it overlaps, to guarantee a tight seal. But remember, an 80-pound roller can be difficult to manage on a 12/12 slope so use your best judgment on how to roll the product, especially the seams, to attain the best seal.
6. Start at the Top or Bottom?
As every roofing professional can point out, when working with your underlayment, it’s always best to start at the bottom of the roof, around the eaves, and work your way up from there. Consider how water will run down the roof. If you start at the top, water can collect in the overlaps and eventually seep beneath the underlayment. By starting at the bottom, you’re creating a surface where water will run over the overlaps. Some manufacturers allow for a vertical installation instead of horizontal so, again, refer to the manufacturer for guidance!
A self-adhered underlayment is a great product. One that, when installed properly, will offer superior protection for a long time. Follow these tips to ensure you get the installation done right!
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