Frequently Asked Questions In Commercial Roofing
While FAQs about commercial roofing sounds pretty straightforward, there's lots to discuss. Let's talk about commercial roof coatings and liquid applied roof membranes.
Why would we talk about liquid applied roof membranes if we're discussing roof coatings today? Because each used similar, if not the same base material. So we want to avoid any confusion and we want to use each for its best application.
Before we get too much further it sounds like we should define these.
The definition for coatings is a fluid applied adhered coating used for roof maintenance or repair, or as part of an assembly. Now typically roof coatings are installed on top of an existing roof membrane.
Liquid Applied Roof Membrane
Liquid applied roof membrane is a roof membrane constructed in place, using a liquid resin and a fabric reinforcement. It's applied directly over insulation, cover board, or an existing roof membrane in a re-cover scenario.
The above roof coating definition comes directly from the International Building Code, where the definition for a liquid applied roof membrane comes from the Roof Coating Manufacturers Association. So these are really solid definitions.
Now that we've defined things, let's get a little bit more technical with this discussion.
A roof coating has a number of uses. Although it's not a weather proofing membrane, it certainly is used to extend the life of an existing roof by providing protection from the elements. And a coating can minimize or avoid the need to tear off an existing roof and avoid operational disruptions. It can also extend the life of the roof. We have a lot of asphalt roofs in place right now, and using a coating is an effective application.
Coatings can also change the color of a roof. The general idea is that we want to coat a dark roof to make it lighter and more reflective. Most roof coatings are white and highly reflective. Simply put, this helps reflect the energy from the sun, reduce the amount of heat absorbed into the building, and potentially reduce air conditioning costs. And we should point out that actual energy savings are going to vary based on climate zone, geography, and utility rates and things like that. But a roof coating with a nice effective thermal layer in a roof is really going to go a long ways to help save energy use in a building.
Another important point is that coatings are not intended to repair roof leaks. Before we install a roof coating, it's good roofing practice to check for trapped moisture and repair leaks and any existing damage.
So let's switch gears now... Let's talk about liquid applied roof membranes and when they would be used.
The primary function of a liquid applied roof membrane is to protect the building from the elements, not just extended service life. So they're very different from coatings. So from a long-term point of view, we could use roof coatings actually to help maintain our liquid applied roof membranes, therefore we avoid a roof tear off.
Liquid applied materials are also transported in buckets, which fit easily into elevators. So when we're re-roofing an operational building, or a skyscraper, a liquid applied roof membrane can be a logical option.
So we can install these over many substrates and over many types of roofs. Two good examples are existing metal panel roofs and existing modified bitumen. In both cases it'll help extend the life of those roofs. However the ability of a liquid applied roof membrane to protect against the elements depends directly on the substrate to which it's adhered. If we have too much movement at a crack, a transition, an insulation board joint for example, this can damage the membrane.
Now that we have worked through some of the technical differences between these two products, why don't we talk a little bit more about some of the installation differences.
A liquid applied roof membrane starts with the application of a base or foundation layer. We broom in the fabric reinforcement and encapsulate that with another layer of base coat. Then we add two or more layers of top coat, which gives us our seamless membrane.
And a roof coating is installed by brushing rolling or spraying a layer of base coat and a layer of top coat. So pretty significant differences there. Regardless of which membrane or which system type you use, you still want to do proper preparation of the substrate, which really means it needs to be clean and dry, you have to check whether or not you need to use a primer or not, we need to repair any damage repair any leaks before we put either system down.
Liquid applied roof membrane, depending on its substrate, may require additional preparation at penetrations, transitions, board joints, any place that we could anticipate movement. Additional reinforcements might also be necessary in the base level.
So a good way to think about this, roof coating is used on existing membranes. A liquid applied roof membrane is used for new roofs, re-roofing or re-cover an existing roof. Both can be the roof surface, both are restorative, but a coating is more of a maintenance item where a liquid applied roof membrane is just that - a new membrane.