Yes. The heat from direct sunlight or temperatures above freezing allow the glue tabs beneath the edge of the shingle to become tacky. This causes the top shingle to seal to the shingle beneath it. In some cases, a separate cold application sealant is applied to the bottom of the shingle edge to ensure a proper installation. When the roof is snow covered or winter weather is expected, it’s best to wait due to safety concerns.

Yes, if you only have one layer. New Jersey Building Code allows a new roof to be installed over one layer of old roof. The reason why you cannot have three layers in total is because of the weight. Each layer of roofing materials is very heavy, and with a snow load on top, this added weight could cause the rafters in the attic to break or a complete structural failure. Most homes have one or two roofing layers.

As the summer sun hits a dark colored roof, it has been found that the temperature directly underneath the shingles can reach 150 degrees. This thermal transition enters into the attic causing temperatures to reach around 110 to 120 degrees. When the roof color is changed to a lighter color, the temperature beneath the shingles drops approx. 10 degrees. At 150 or 140 degrees, this 10-degree difference is still hot. Homeowners have found this to be true as well, so selecting a lighter colored roof will not accomplish the goal of making a noticeable temperature change within the home. Attic air sealing and added insulation would be the better solution.

The national average intended service life of an older roof is between 18 – 20 years. This doesn’t mean the roof will start to leak at that point, but the materials themselves will show significant signs of deterioration, staining, and granule loss. It’s best to be proactive vs reactive when replacing a roof that protects everything within the home.