06/24/2026
Here’s an example of what goes underneath the shingles of a roof. Typically you’ll find tar paper underneath older roofs. Tar paper is slowly being phased out in favor of this synthetic underlayment. A synthetic underlayment is considerably more water resistant, and it does not tear like old tar paper. If I handed you a strip of synthetic you would not be able to tear it without tools. This makes it a much more robust product to have installed and additionally it’s much safer for the installers. We re-roofed this monster house in Round Rock a couple years ago and I guarantee my crew would not be happy walking on these steep inclines without synthetic underlayment installed.
In the valleys you can see the ice and water barrier installed. This is added through valleys and around any penetrations on the roof. In the north it’s added along all eaves to prevent ice damming. In the second picture you can see the 20” valley metal flashing that will be installed through the valley. With such redundancy the valley which are most prone to leaks become some of the least likely entry points for water to pe*****te your roof system.
A roof is more than just shingles. If someone offers to overlay new shingles over your existing roof, show them the door. They do not have your best interests in mind.