When you receive a proposal for roofing repair or roof coating, it will include a description of the problem areas (if any) and the work to be done. That description will include a number of technical roofing terms that you may not be familiar with.
Below are the most common roofing terms you’re likely to come across in proposals:
Elastomeric coatings are essentially heavy bodied acrylic paints where the acrylic molecule has been modified to give the coating more elongation or enhance the ability of the coating to stretch. The elastomeric quality allows the coating to stay intact while the roof goes through its normal process of expanding during the day, and contracting at night.
The purpose of the coatings is to protect the roof from the damaging rays of the sun. The point of roof coatings is to reflect the ultraviolet rays of the sun back into the atmosphere as opposed to being absorbed by the asphalt in the roof. Roofing asphalt can be damaged in a relatively short period of time if it isn’t properly coated.
Coatings should not be confused with a sealant. Although the coatings have a level of water resistance, coatings by themselves are not designed to prevent or correct leaks. If a roof has a leak, the defect in the roof must be addressed first, and then coated to protect the material used.
Modified Bitumen Roofing
Modified bitumen roofing, as roofing goes, is a relatively new product that has many uses as a repair material. It is essentially a replacement material for built-up roofing. As opposed to built-up roofing, which is laminated on-site, modified bitumen is laminated at the factory and seamed on site. Therefore we can now install class A fire code roofing for low sloped structures without needing a tar kettle and manpower to install conventional built-up roofing.
That this material is comparably expensive and built-up roofing is still less expensive than modified bitumen with the exception of small areas. If you are having a roof installed on a patio or garage, modified bitumen would likely to be more cost-effective. Larger areas may be more cost-effective if done with built-up roofing.
One area in which modified bitumen is often the best choice is for roof repairs. Often low sloped roofs have an area where the roof does not drain well. The cost of re-sloping the roof may be prohibitive, but installing modified bitumen in the area is a more cost-effective way of installing a new roof in just the area it is needed. Re-sloping is more cost-effective when re-roofing time eventually comes.
Parapet Roofing/Parapet Walls
Here in Tucson, we have a lot of Territorial and Santa Fee style houses, both of which normally have parapet walls to some degree. The parapet wall is any wall that protrudes above the roofline. The roofing material is wrapped from the horizontal deck surface, up the wall and usually ends at a metal flashing or a mastic seal. The portion of the parapet wall that starts where the roofing stops usually consists of stucco or block and is not considered part of the roof.
Flashing and flashings may be the most overused roofing term that exists. It can mean anything from a metal component to a mastic seal. The only thing I can offer to help clarify is that usually it is a material that is used to carry water from one component on a roof to another.
Instead of simply applying a heavy coating of a sealant, a 3-course seal has a membrane or fabric tape embedded into a mastic type sealant. The process is to apply a layer of mastic sealant, a layer of membrane and then another layer of sealant, hence the “three” courses that justify the term.
A scupper drain is basically a metal tube that carries water through a wall. There are important flashings (again that word!) that make the seal to the roof more reliable, but what is important to most people that have them is the fact they carry water though walls.
Chip-Out Scupper Drains
Scupper drains seals are generally considered the most likely cause of a leak on a house that uses scupper drains as a means of roof drainage.
We “chip-out” the old seal to expose the metal drain flashing below; this allows our new seal to adhere directly to the metal drain. If this time-consuming process is skipped, the new sealant will only adhere to the old seal. In the event that the old seal separates from the scupper drain, the new seal will do nothing in terms of keeping water out.
Additionally, if old seals are not removed at the drains, the seals will naturally become thicker and as a result might restrict the drainage of the roof into the drain, creating a ponding condition that’s less likely when drains are chipped out.
Scupper drains are often covered with decorative coverings. These coverings or embellishments are referred to as canales. Canales can be made of clay, concrete, wood, metal, or stucco. A canale’s sole purpose is to make the metal tube more visually appealing.
Header boxes, sometimes called leader boxes, are funnel-shaped metal boxes that attach to the outside wall over scupper drains. They are used to accommodate downspouts, which are used to carry water to the ground.