Roofing is typically attached to commercial buildings in one of two ways; full adhesion or mechanically. There may be other methods that you have heard of but these are the most popular ways to fasten a roof. Regardless of the method you use, there will be a layer of insulation beneath the roof and a metal deck below that, which is fixed to the structure below. It is important to understand the differences and to know what your building needs. Failure to match your roofing with the needs can cause you to pay for value that you don’t actually need.

Mechanically attached roofing

Taking up almost 80 percent of the market, mechanically attached roofing is the most popular option for commercial buildings. These systems can be installed quickly and are less expensive. They also have the advantage of being easy to inspect, which means they can quickly be validated by verifying the fastener pattern and their correct installation.

Most buildings have a metal deck, a layer of insulation and then a roof. Installation of a mechanically attached roof involves rolling the membrane down and applying screws directly through the insulation boards into the metal deck. The screws will be driven in at the edge of the membrane and are then covered with the edge of the next sheet to be rolled out. The membranes are heat-welded together to create a watertight seal, and you end up with a flat, waterproof surface with no gaps.

Fully adhered roofing

These roofing systems are glued directly to the insulation layer below it. This means that the insulation boards act to insulate and secure the roof to the metal deck, which requires more screws. This is a more expensive method and more time-consuming. Because large quantities of glue need to be applied at the same time and at the right temperature, this method is more challenging than people realize. Once the glue has dried to form the right tackiness, a roller is used to press the membrane to the insulation.

This roofing option is often chosen because it is thought to be more resistant to leaks. Builders believe that if water was to get through a hole, it would travel under the membrane past the glue. The problem with this is that you will not even realize there is a hole until water has pooled and the glue has become degraded. This causes bigger problems than knowing about a leak right away as the accumulated water can spread and damage a larger area of the roof.

Final thoughts

Fully adhered attachments also provide higher Factory Mutual wind-uplift ratings. These are ratings assigned to commercial properties by a large insurance firm. As beneficial as it is to have these higher ratings, there is really not much need for them in areas outside of coastal or high-wind areas. At this time mechanically attached roofs dominate the market but there is still a demand for fully adhered roofing too. Contact us to determine which roof attachment type will work best for your budget and building.

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