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
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
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
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
The Russo Report: A Sound Remediation Solution for Low-Slope Roofs
Michael Russo is a contributing writer to Roofing Contractor. He can be reached at email@example.com.