The Federal Aviation Administration (FAA) has continuously, consistently and actively encouraged a balanced approach to noise problems at our nation’s airports.

The Federal Aviation Administration (FAA) has continuously, consistently and actively encouraged a balanced approach to noise problems at our nation’s airports. A reasonable approach to noise mitigation is important, in part, because new noise certification and abatement procedures have in many instances been extremely successful in reducing noise impacts at airports across the country without access restrictions.

The Aviation Safety and Noise Abatement Act lists the soundproofing of public buildings as a key step in most noise compatibility programs. In this regard, commercial roofing systems have proven to be worthwhile targets for sound remediation.

However, sound remediation solutions for low-slope roofing also need to consider good roofing practice and proper moisture control, as part of an environmentally friendly roof retrofit solution.

To achieve this, one manufacturer has developed and independently tested a roof system consisting of a high mass layer of gypsum roof board and 1 inch minimum porous fiberglass or fiber insulation board (non-batt). Virtually any new or existing roofing membrane can be used as the waterproofing layer over the top of this system.

The rock wool or fiber glass insulation below the gypsum board serves as a ventilation layer to alleviate the common problem of moisture entrapment during roof retrofits. With sound remediation as the goal, these new layers of insulation can be installed while leaving the existing roof in place. This makes the entire project more sustainable, as the old roof will not present a costly disposal problem for the building owner.

In addition, should the architect, roofing contractor or building owner desire increased insulation R-value, additional insulation can be installed during the sound remediation process. Depending on climate, this can result in a dramatic improvement in energy savings as well.

The manufacturer recently received test reports from ATI in York, Pa., which confirms the company’s initial findings. The improvement in sound isolation with the new system is significant.

ATI discovered an 11dB improvement in STC rating, which basically reduces the sound level through the existing roof system by more than half.

The existing roof assembly without the gypsum board was measured at 43dB STC, and the same assembly with a mineral fiber board and 5/8” gypsum came in at 54dB STC. This performance also safely achieves the LEED requirement for schools, which currently stands at an STC of at least 50dB. In fact, this same system can work for residential roof applications as well.

Because current lightweight construction techniques are relatively transparent to sound, the roofing system needs a high mass barrier to reduce sound intensities at or near airports. The fibrous insulation below the gypsum board also plays a significant role by dampening sound through multiple layers of material - both high mass and soft - thus diminishing sound energy and letting the mass of the roof insulation system turn it into heat energy.

As mentioned above, a successful sound remediation system for roofing must also address the potential for moisture accumulation within the roof system. Instead of entrapping moisture, the fibrous insulation below the gypsum allows moisture to travel to the roof edges, where newly developed metal edge systems use natural vapor pressure to vent this moisture to the outside.

Most major roofing manufacturers now carry either metal edges or cap systems for ventilating walls, which are supplied by individual edge system manufacturers.

Besides the sound and moisture solutions, the roofing contractor can easily add R-value on most roofs by using foam insulation to beef up the energy efficiency of the fibrous glass insulation layer.

A fourth benefit of the sound remediation system is it does not require a roof tear-off that would both disrupt building occupants and create a disposal problem.

Indeed, the FAA now has a proven and independently tested solution to offer those who are complaining about sound intrusion levels at or around airports. Whether the remedial work is subsidized by the FAA or not, the agency can suggest the system to building owners as a solution to sound, moisture, energy and sustainability challenges.