Existing Home Retrofit Process
There is much to know regarding the process of insulating existing homes in the Southern States. It is very difficult and the most most physically and mentally demanding task in FL construction. It should only be performed by a trained SPF contractor with experience working in attics. The typical attic is very difficult to move around in and proposes challenges the entire time the attic occupied. To properly spray foam every area of a roof deck or gable end wall, a spray tech must wear protective gear, rely on an ambient air breather for oxygen, and carry a hot, heavy hose through wooden trusses in an area that has no floor, while withstanding temperatures approaching 150 degrees. Needless to say the spray techs you choose have to be experienced and strong willed.
Insulation Removal and Why
Before any insulation can be applied to the roof deck, the existing baseline insulation must be removed.
The common types of residential insulation used here in the U.S. are rolled fiberglass batting and the “blown-in” or “drop in place” types; cellulose or fiberglass, fiber/wool mixes etc. etc. They are the cheapest insulations and the easiest to install as they are simply dopped or blown on the attic floor. Since the Thermal Barrier is at the ceiling/attic floor, the airspace above has to be dealt with, so it is vented to the outside through Roof or gable end venting. This scenerio leaves the home with a scorching attic most of the year.
Air Space Control
These baseline insulations (open attic assembly), if coupled with any roof deck insulation (closed attic assembly), would create an all-sided pyramid of insulation. Every Insulation Co. should know the cardinal rule of insulation is that it should never be applied twice, unless the two are applied back to back, not with a dead air space in between. This air space would be uncontrollable in terms of humidity and temperature. With the application of SPF to the roof deck, there is no need to insulate at the attic floor since the attic air and conditioned air below would not be at odds. In fact, they need to become one or “acclimate” so that the attic temperature rises only a few degrees higher (Summer) and a few degrees lower (Winter) than the living space. The home’s HVAC System will now be responsible for removing any moisture in the attic since the two spaces are merely divided by 1/2” of drywall. Blocking the heat at the roof line leaves the attic cool and the conditioned living space air below makes sure it remains so. If the attic floor insulation were allowed to remain in place, moisture would build up in the attic since there is no control of the airspace.
Toxic Attic Space
U.S. Dept. of Energy states that 80% of a home’s dust comes from the attic space. The average American breathes 3400 gallons of air per day. A vented attic with typical fibrous “drop in place” insulations is simply the worst way to insulate. The typical U.S. attic has over one thousand pounds of dirty, toxic, failing insulation. They are manufactured with an abundance of fire retardants such as urea and phenol formaldehyde’s, acrylics used as binders, and asphalts that have adverse health effects and contribute directly to poor indoor air quality. From our experience, one out of every 3 attics contain some form of rodent feces which presents a host of health ailments. =
The application consists of a two-component foam using specific proportioning and personal protective equipment. This equipment, coupled with certain work practices and engineering practices including ventilation, are used to minimize exposures to the chemicals used to make SPF during the job. As a homeowner, you can minimize or eliminate exposure to the chemicals used to create spray foam by carefully following your contractor’s guidance about how long to leave the home during the installation, job completion, and cleanup.
Ventilation: Ventilation used with workspace containment removes chemicals from the isolated area via negative pressure. Having a negative pressure in a contained work zone (attic) will draw in air from existing roof venting and exhaust the work zone air. Active ventilation is achieved by using one or more turbine fans to draw air to or from the workspace and create a negative pressure inside the workspace. We must give careful consideration to the location of the exhaust. Ideally, exhaust is released to an unoccupied space (roof vent) where it is not likely to be drawn through an air intake.
Occupancy Recommendations: It is the recommendation of the spray foam chemical manufacturers and Central Florida Spray Foam llc, that the residence be evacuated for during the time of spray up to 24hrs after the spraying is complete. Reoccupancy time is dependent on a number of factors, including SPF formulation, the amount of foam applied per volume of space, temperature, humidity, the degree of ventilation and other variables. In addition to the release of airborne SPF chemicals during spray application, certain components can be liberated from some newly-installed SPF products for a short period of time following installation.
Evaluation reports for many types of building products, including SPF insulation, often include the suggested reoccupancy time, which is variable: for an interior application by a contractor using two-component high-pressure SPF, 24 hours is common, and for an interior two-component, low-pressure SPF kit application using store bought materials, one hour is common.
HVAC System: During the application of SPF, the existing HVAC unit should be completely shut down to avoid any unnecessary air exchanging. Most HVAC ducts have leaks within the attic space which may cause the smell of the newly applied SPF to infiltrate into the ducts and also the living space.