ARMA Technical Bulletin
Moisture content within a roofing assembly may fluctuate significantly over the life of the roof depending on a variety of factors including, but not limited to, moisture in the existing roof assembly at the time of installation: interior and exterior temperatures,
interior and exterior humidity conditions, deck type, under-deck ventilation, amount and location of insulation and presence of vapor retarders/air barriers in the roof assembly.
The potential for condensation and moisture buildup in a membrane roof system from interior moisture sources has always been and should continue to be an issue that must be accounted for in roof system design. Furthermore, the color, solar reflectance and
thermal emittance of the roof surface can affect a roof system’s drying potential and, therefore, the buildup of moisture in the roof system.
Moisture buildup in the roof assembly can result in deck deterioration, including rotting wood decks, corrosion of metal decks, growth of mold and other organisms, deterioration of the roof system and re-emulsification of certain water-based adhesives.
The use of light color and reflective roofing is increasing, driven in part by requirements such as the California Building Standards Commission’s Title 24, LEED and local code requirements across the U.S.
Changing the color of a roof membrane from a dark or non-reflective surface to a light color or highly reflective surface both reduces the amount of time the roof spends in a “drying” mode and the roof temperature when the roof is in a “drying” mode. When there is a source of interior humidity, a light colored or highly reflective roof surface can allow moisture and liquid water to build up in the roof assembly with less opportunity to evaporate or dry. Accumulation of moisture within roof systems can be exacerbated in buildings with elevated humidity or periods of excessive moisture generation and if not addressed in the design of
the building envelope. Some examples of moisture generators include:
■ Apartment and condo buildings (showers, cooking, air humidifiers, etc., produce high levels of interior moisture)
■ Swimming pools, food processing, paper mills and foundries
■ New construction with high interior construction moisture (e.g., from freshly poured concrete, space heaters, wet insulation, drywall installation, etc.)
■ A compact ceiling assembly where there is typically drywall, batt insulation, roof deck and membrane with little or no insulation above the deck, no vapor retarder or air barrier in the system and with little or no ventilation below the deck
■ Reroof conditions where moisture may be present in the existing system.
In new construction projects, the design professional must evaluate the anticipated interior and exterior conditions and design the proper water vapor control (including consideration for transfer of water vapor via diffusion and air flow). This evaluation should include the necessary calculations to ensure there will not be a condensation problem and a determination regarding whether a vapor retarder, air barrier or underside deck ventilation is necessary. If adequate water vapor control measures cannot be integrated in the design, use of light colored or highly reflective roofing may create condensation issues.
Regarding tear-off, recover and coating applications, a roofing professional should evaluate the existing roof assembly for signs of water infiltration or condensation issues (water stains, wet or deteriorated insulation, deck deterioration, organic growth). The
professional should also determine whether there are interior vents (such as bathroom exhaust fans) and, if present, confirm that they are all properly ducted to the outside and in good condition, so they do not allow moisture to enter the roof system. A roof design professional or climate control specialist should be consulted to evaluate the existing conditions and to develop a plan to address moisture issues within the existing roof assembly.
Some things that can be done to help control moisture accumulation in the roofing assembly include:
■ Remove wet areas within the existing roof system prior to recovering the system with a new assembly
■ Provide insulation above the deck to shift the location of the dew point
■ Use at least two layers of insulation with staggered joints to prevent moisture migration through the joints between the insulation boards
By acting as an “interventionist,” HR becomes every worker’s first stop when they need the right solution for their non-workplace needs. An interventionist HR team should be equipped to deliver exactly what’s needed at each stage of the employee’s life cycle – whether that’s marriage, re-marriage or divorce, a child’s birth or adoption, death of loved ones or retirement.
As construction firms struggle to deal with the perennial need for skilled workers, a deeper examination is needed to determine whether they are equipped, holistically, to deliver in today’s new normal. Is HR positioned as a first stop or are there other gateways to the workforce? How can they be unified? Is the technology for communicating and delivering benefits to employees efficient, user-friendly and secure? Are employers fully leveraging their employee data to be better able to anticipate future needs and to advance HR’s role as interventionist?
The “new” post-pandemic normal is fluid and dynamic, assuring everyone that there is no more “business as usual.” The best way forward is to rethink what matters to their current and future workers and how employers can best go about delivering that service.
Hanan Nemeth is Vice President of Human Resources Consulting at HUB International, Gainesville, Florida.
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