The Effect of Wet Insulation on the SUNLIFE Roofing System
There has been and still remains great controversy over the questions concerning wet insulation. Can it be dried out? What are the effects on the "R" factor? Are vents effective or do they contribute to the problem?
Once a leak has occurred in the roof membrane, the "R" factor in this area is reduced substantially. If the leak in not repaired, the area will migrate and encompass a much larger area (ex. sponge). If the insulation is organic (fiberboard, perlite, etc.), prolonged exposure will cause irreversible damage to the insulation thus destroying the insulation value of the roof structure. Over a period of time, this is observed by a "rotten" odor upon core inspection and subsequently, deflection of the roof membrane.
Although roof leaks may be repaired, the "R" factor cannot be restored and the low areas created by the decomposition of the insulation causes "ponding water". Left unattended over a long period of time without a periodic maintenance program the only remedy is "tear off".
The other types of insulation are inorganic (ex. fiberglass, foamglass, polyurethane, etc.). These systems do not decompose with prolonged exposure to saturation. Once leaks have been stopped and ventilation established, eventually the moisture in these systems will dissipate and the "R" factors will be restored with very little loss. This is complicated at times by the presence of a "vapor barrier". When vapor barriers are present the drying time can be increased substantially.
To understand the sequence, water enters through the membrane saturating the insulation. Initially this is a relatively small area; however, if left unchecked this can increase to very large areas depending upon shape and type of the roof, the type of insulation, and if a vapor barrier is present.
The evidence of moisture present in roofs can always be determined by expensive testing methods such as "infra red" detection, capacitance testing, and nuclear testing. It can simply be identified during the summer months by observing "blisters" in the roof membrane. "Blisters" are caused by moisture being subjected to a heat source; thus, converting the liquid into a gaseous state. By actual area, the conversion ration is 1500 to 1 by volume. In other words, a drop of water will convert in size if all were converted to a gas 1500 time the original size. Not all blisters are caused by water entrapment. Some blisters are "interply" which resulted primarily form association with initial installation, wet felts, high humidity, etc.
SUNLIFE's main advantage regarding blistering is the fact that it is white and the surface temperate is reduced by 43 degrees F. Thus, the conversion of liquid to gas is reduced substantially.
We must understand that the normal direction of expulsion of this gas is always down into the building. Air conditioning normally creates a lower pressure inside the building thus a normal sequence of drying will occur without any external method, once source of water entering the membrane is shut off. This complicated where a vapor barrier is present. The time can be actually doubled, tripled or even quadrupled. The normal sequence for roofs without vapor barriers is one summer season.
While not debating the subject of roof venting, our company has experienced exceptional results with "one way" vents on both areas with vapor barriers and those without.
Over inorganic insulation, one vent per 10 squares has been adequate to provide the added release of the vapor created by summer heating.
In summary, virtually all types of built up roofing covered by SUNLIFE Roofing Systems have had some form of wet insulation problem. After restoration with the SUNLIFE Roofing System, there are virtually no blisters. Most of the blisters that I have personally observed have been aided by internal heat sources such as boilers, electrical equipment, etc. To have a blister (the major contributor to roof membrane failure) two constants must be present, moisture and heat. SUNLIFE simply reduces the heat source by reducing the surface temperatures. Thus, in most areas, moisture in the insulation does not provide an overcoming obstacle to the SUNLIFE System. In the event that the area is too large, observation during the summer months would eliminate the roofs not acceptable. We will not take a roof with over 20% blistering. Careful inspection and core samples are the best tools to determine the viability of the surface and its acceptance by SUNLIFE.
Jerry P. Auten
- SUNLIFE Systems International, Inc.
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