Insulation system with variable position vapor retarder

Abstract

A method for positioning a vapor retarder within an insulation system to reduce condensation within the insulation system is provided. The incremental change in temperature per R-value of insulation is calculated by determining the temperature differential between the exterior temperature and the interior temperature and dividing this temperature differential by the R-value of insulation. Various possible temperatures for the vapor retarder within the insulation may be determined using the incremental change in temperature. The R-values of the insulation layers on either side of the vapor retarder may be determined by a condensation potential analysis. Preferably, the vapor retarder is positioned within the insulation system at a location where its temperature remains above the interior dew point temperature in the summer and above the exterior dew point temperature in the winter. An insulation system including a variably positioned vapor retarder is also provided.

Description

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

The present invention relates generally to an insulation system that contains a vapor retarder and more particularly to an insulation system in which the vapor retarder is variably positioned between insulative layers depending on geographic location and/or condensation potential.

BACKGROUND OF THE INVENTION

Fiber insulation is typically formed of mineral fibers (e.g., glass fibers) or organic fibers (e.g., polypropylene fibers), bound together by a binder material. The binder material gives the insulation product resiliency for recovery after packaging and provides stiffness and handleability so that the insulation product can be handled and applied as needed in insulation cavities of buildings. During manufacturing, the fiber insulation is cut into lengths to form individual insulation products, and the insulation products are packaged for shipping to customer locations. One typical insulation product is an insulation batt, which is suitable for use as wall insulation in residential dwellings or as insulation in the attic and floor insulation cavities in buildings.

Most insulation products have a vapor retarder on one side of the insulation product to retard or prohibit the movement of water vapor through the insulation product. Insulation products that contain a vapor retarder facing are installed with the vapor retarder side placed flat on the edge of the insulation cavity. Water vapor moves from an area of high vapor pressure to an area of low vapor pressure. Thus, in winter months, when the outside air is cooler than the inside air, the water vapor drive is from the interior of the building to the exterior of the building. In summer months, when the air conditioned air is cooler than the external air, the water vapor drive is from the exterior to the interior.

In winter months, when the vapor drive is from the interior to the exterior, it is desirable to place the vapor retarder on the inside of the insulation cavity (e.g., toward the inside of the building) to prevent condensation within the insulation product. However, during the summer months when the outside air is warmer than the inside air, this internal placement of the vapor retarder may result in condensation collecting in the insulation product. Consequently, in summer months, it is desirable to place the vapor retarder on the exterior side of the insulation cavity (e.g., toward the outside of the building) to reduce the amount of water vapor entering the building during the air conditioning season. However, this external placement of the vapor retarder may result in the vapor cooling and condensing within the insulation in the winter. Thus, in geographic locations that have seasonal temperature changes, a single vapor retarder placed on either the inside or the outside of the insulation cavity may result in condensation of water vapor into the insulation at some time during the year.

It has been proposed by some building researchers to place a vapor retarder on both the inside and the outside of the insulation cavity to reduce condensation in both the winter and the summer months. (Yost, et al., Basement Insulation Systems, Building Science Corporation, 2002, page 7). Although this dual vapor retarder approach is effective in reducing the amount of condensation that occurs in both the winter and the summer months, if moisture does enter the insulation, such as by a rip or tear in the vapor retarder that may occur during the installation of the insulation product, the water vapor becomes trapped between the opposing vapor retarders, and the dual vapor retarders prevent the moisture in the insulation from drying to either the inside or the outside of the building.

Another approach that may be used to reduce condensation is to install a water-permeable vapor retarder on either the interior or the exterior of the insulation. The water-permeable vapor retarder allows water to escape in humid conditions. In dry conditions, the water-permeable vapor retarder retains its vapor retarding abilities. (1997 ASHRAE® Handbook Fundamentals, Inch-Pound Edition, American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., chapter 23, page 8). Thus, the water-permeable vapor retarder permits a wall to remove condensation from the insulation in the summer months. Although such a vapor retarder may be able to remove some condensation from within the insulation, water-permeable vapor retarders are very costly and thus impractical.

Water vapor condensing and collecting in the insulation product results in a damp insulation product, which causes mold, mildew, and decay of the wood studs in the framing of the building, and a loss in their insulting properties. Thus, there exists a need in the art for an insulation system that reduces the condensation of water vapor in insulation products in various geographical locations.

SUMMARY OF THE INVENTION

An object of the invention is to provide a method for positioning a continuous vapor retarder within an insulation system to reduce condensation. First, the temperature differential between the exterior temperature and the interior temperature of the building is calculated. This temperature differential is then divided by the R-value of the insulation to obtain the approximate amount of temperature increase/decrease per single R-value of insulation (e.g., “the incremental R-value temperature change”). Thus, for each R-value of insulation, the temperature of a vapor retarder will increase or decrease in temperature from the internal or external temperature in an amount approximately equal to the incremental R-value temperature change as the vapor retarder is moved through the insulation.

Various possible temperatures of the vapor retarder within the insulation system may then be determined using the incremental R-value temperature change. The R-values of the insulation layers on either side of the vapor retarder may be determined by a condensation potential analysis for the particular geographic region. To reduce condensation, the vapor retarder is positioned at a location between a first layer of insulation and a second layer of insulation where its temperature remains above the interior dew point in the winter and above the outside dew point temperature in the summer. Preferably, the vapor retarder is positioned within the insulation system such that the vapor retarder temperature is above the interior dew point in the summer and above the outside dew point temperature in the winter for the entire year.

In some geographic locations, the placement of the vapor retarder may result in a small amount of condensation within the insulation system at some point during the year. An analysis of the amount of daily condensation that occurs may be conducted. The amount of condensation that may occur within the insulation system depends on the temperature difference between the dew point temperature and the vapor retarder temperature and the length of time that the temperature of the vapor retarder is below the dew point temperature. By positioning the vapor retarder within the insulation system such that the amount of time that the temperature of the vapor retarder is below the dew point temperature is reduced, the amount of condensation will also be reduced.

By conducting an analysis of the condensation potential for an insulation system 24 hours a day for 365 days, the total condensation potential for the entire year for a given vapor retarder position may be determined for a given climate. This condensation potential may then be quantitatively compared to the condensation potentials for vapor retarders at other positions within the insulation system and an optimum location for the vapor retarder at that geographic location may be determined which reduces the overall condensation potential of the insulation system over an entire year for that given geographical location. Preferably, a computer program is used to conduct these yearly condensation potential calculations.

Another object of the present invention is to provide an insulation system that contains a continuous vapor retarder that is variably positioned between a first insulation layer having a first thickness and a second insulation layer having a second thickness. The thicknesses of the first and second insulation layers may be determined by the analysis described above. The first layer of insulation is affixed to a wall, which is preferably a wall that does not contain a wood or metal stud framing structure. In a preferred embodiment, the first layer of insulation is a foam board or high density fiberglass insulation that has sufficient strength and durability to support a vapor retarder and subsequent layer of insulation. Mechanical fasteners or adhesives may be used to fasten the first layer of insulation to the wall. The first layer of insulation may be applied in a step-wise fashion until the wall is covered. A continuous vapor retarder is then attached to the first layer of insulation. Alternatively, a vapor retarder may be pre-applied to the first layer of insulation. When the vapor retarder is pre-applied to the first layer of insulation, the joints between the first insulation layers may be taped to provide a substantially continuous vapor retarder.

Lineals are then horizontally and vertically affixed to the vapor retarder to form insulation spaces. Lineals may be formed of a base member and two vertically projecting arms. The second layer of insulation is placed into the insulation spaces adjacent to the vapor retarder. Preferably, the second layer of insulation contains a permeable finished surface that provides an aesthetic appearance and which meets functional requirements such as damage resistance and fire resistance. If the second layer of insulation does not contain a finished surface, a separate finished surface may be attached to the second layer of insulation. It is preferred that the finished surface does not act as a second vapor retarder. Trim pieces are then attached to the lineals over the finished surface to complete the insulation system.

The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows, in conjunction with the accompanying sheets of drawings. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic elevational illustration of a masonry wall;

FIG. 1 b is an end view of the schematic illustration depicted in FIG. 1a;

FIG. 2 a is a schematic elevational illustration of the placement of a first sheet of the first layer of insulation on the concrete block wall depicted in FIG. 1a;

FIG. 2 b is an end view of the schematic illustration depicted in FIG. 2a;

FIG. 3 a is a schematic elevational illustration of the placement of a second sheet of the first layer of insulation;

FIG. 3 b is a an end view of the schematic illustration depicted in FIG. 3a;

FIG. 4 a is a schematic elevational illustration of the placement of the lineals on the first layer of insulation;

FIG. 4 b is an end view of the schematic illustration depicted in FIG. 4a;

FIG. 5 a is an end view that depicts the cross-sectional configuration of a lineal for use with the insulation system of the present invention;

FIGS. 5 b-5f are end views that depict the cross-sectional configurations of various trim pieces for use with the insulation system of the present invention;

FIG. 6 a is a schematic elevational illustration of the placement of the second layer of insulation between the lineals;

FIG. 6 b is an end view of the schematic illustration depicted in FIG. 6a;

FIGS. 7 a-7d are schematic elevational illustrations of various placements of the vapor retarder within a modular insulation system;

FIG. 8 a is a schematic elevational illustration of the placement of a vapor retarder in Experimental Insulation System 1;

FIGS. 8 b-8c are graphical illustrations depicting the outside temperature, the outside dew point temperature, and the vapor retarder temperature vs. the time of day for Experimental Insulation System 1;

FIG. 9 a is a schematic elevational illustration of the placement of a vapor retarder in Experimental Insulation System 2;

FIGS. 9 b-9c are graphical illustrations depicting the outside temperature, the outside dew point temperature, and the vapor retarder temperature vs. the time of day for Experimental Insulation System 2;

FIG. 10 a is a schematic elevational illustration of the placement of a vapor retarder in Experimental Insulation System 3;

FIGS. 10 b-10c are graphical illustrations depicting the outside temperature, the outside dew point temperature, and the vapor retarder temperature vs. the time of day for Experimental Insulation System 3;

FIG. 11 a is a schematic elevational illustration of the placement of a vapor retarder in Experimental Insulation System 4;

FIGS. 11 b-11c are graphical illustrations depicting the outside temperature, the outside dew point temperature, and the vapor retarder temperature vs. the time of day for Experimental Insulation System 4;

FIG. 12 a is a schematic elevational illustration of the placement of a vapor retarder in Experimental Insulation System 5; and

FIGS. 12 b-12c are graphical illustrations depicting the outside temperature, the outside dew point temperature, and the vapor retarder temperature vs. the time of day for Experimental Insulation System 5.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. It is to be noted that like numbers found throughout the figures refer to like elements.

The present invention relates to an insulation system that contains a vapor retarder that is variably positioned between insulative layers depending on geographic location and/or condensation potential. In particular, the vapor retarder is positioned with a first insulation layer having a first thickness located on one side of the vapor retarder and a second insulation layer having a second thickness located on the opposing side of the vapor retarder. The first and second thicknesses may be equal to each other, or one thickness may be greater than the other. 10040] Temperatures of the vapor retarder vary depending upon its location in the insulation system. For example, a vapor retarder placed on the exterior side of a wall with all of the insulation placed towards the interior will have a temperature that matches or nearly matches the outside air temperature. Similarly, a vapor retarder placed on the interior side of a wall with all of the insulation placed towards the exterior will have a temperature that is the same or nearly the same as the temperature of the interior of the building. On the other hand, if the vapor retarder is placed internally within the insulation system such that insulation is located on both sides of the vapor retarder, the temperature of the vapor retarder is insulated from both the interior and exterior temperatures. As a result, the temperature of the vapor retarder will have a temperature that is between the interior temperature and the exterior temperature.

Approximate temperatures of the vapor retarder at various locations within the insulation system at any geographic location may be easily calculated. First, the temperature differential between the exterior temperature and the interior temperature of the building is calculated. The temperature differential between the exterior temperature and the interior temperature is then divided by the R-value of the insulation. The resulting number is the approximate amount of temperature increase or decrease per single R-value of the insulation (hereinafter referred to as “the incremental R-value temperature change”). The thickness of the insulation is generally proportional to the insulative effectiveness, or R-value of the insulation. Thus, for each R-value of insulation, the vapor retarder will increase or decrease in temperature from the internal or external temperature in an amount approximately equal to the incremental R-value temperature change as the vapor retarder is moved at different locations through the insulation.

For example, in the summer, when the internal temperature is less than the external temperature, the vapor retarder temperature will increase in an amount approximately equal to the incremental R-value temperature change for each R-value of insulation as the vapor retarder is moved from the interior of the building toward the exterior of the building. On the other hand, when the external temperature is below the interior temperature, as in the winter, the vapor retarder temperature will decrease in an amount approximately equal to the incremental R-value temperature change as the vapor retarder is moved from the interior of the building toward the exterior of the building one R-value at a time.

Once the temperature increase/decrease per R-value of insulation is calculated, the various possible temperatures for the vapor retarder within the insulation at that geographic location may be determined using the incremental R-value temperature change. The R-values of the insulation layers on either side of the vapor retarder may then be determined by a condensation potential analysis for the particular geographic region.

Condensation occurs when the temperature of the vapor retarder is below the dew point temperature. In the summer, condensation occurs when the temperature of the vapor retarder is below the exterior dew point temperature. In the winter, condensation occurs when the temperature of the vapor retarder is below the interior dew point temperature. Thus, to reduce condensation, the vapor retarder may be positioned between the first insulation layer and the second insulation layer at a location where its temperature remains above the interior dew point in the winter and above the outside dew point temperature in the summer for a majority of the time. Preferably, the vapor retarder is positioned within the insulation system such that the vapor retarder temperature is above the interior dew point in the winter and above the outside dew point temperature in the summer for the entire year.

As one illustrative example, consider an R-13 insulation system in a building at a northerly location where the interior temperature and interior dew point temperature remain a constant 65° F. and 40° F., respectively, throughout the year, the external winter temperature is 16° F., and the external winter dew point temperature is 11° F., the external summer temperature is 84° F., and the external summer dew point temperature is 71° F. By placing the vapor retarder on the interior of the insulation system with all of the insulation towards the exterior of the building, as in conventional systems, the temperature of the vapor retarder will remain approximately 65° F. (the interior temperature). Thus, in the winter, the temperature of the vapor retarder will remain above the interior dew point temperature of 40° F. As a result, there would be no condensation in the winter with this insulation system. This internal placement of the vapor retarder, however, is not optimal for the summer climatic conditions at this geographic location, because in the summer, the temperature of the vapor retarder would be below the exterior dew point temperature (i.e., 65° F.<71° F.). As a result, condensation would occur in the summer. 10046] To reduce this potential summer condensation, the vapor retarder may be positioned within the insulation at a location where the temperature of the vapor retarder is above the exterior summer dew point temperature. Thus, in order to reduce condensation in the summer, the vapor retarder temperature needs to be raised from 65° F. to at least 71° F., .i.e., the temperature of the vapor retarder may be raised at least 6° F.. To determine the R-values of insulation surrounding the vapor retarder, the incremental R-value temperature change is calculated. First, the temperature differential between the external summer temperature and the internal temperature is calculated (i.e., 84° F.−65° F.=19° F.). This temperature differential is then divided by the R-value of the insulation (13) to obtain the incremental R-value temperature change (1.46° F./R-value).

To obtain at least a 6° F. temperature increase in the vapor retarder in the summer, the vapor retarder may be placed at least four R-values of insulation from the interior. (e.g., 6° F.−1.46° .F/R-value=approximately 4 R-values). Moving the vapor retarder a total of four R-values toward the exterior of the building results in a vapor retarder temperature of approximately 71° F. in the summer. A similar calculation for the temperature of the vapor retarder with R-4 insulation on the interior determines that the vapor retarder would have a temperature of approximately 49.9° F. in the winter, which is above the internal dew point temperature of 40° F. Therefore, the vapor retarder may be placed with R-4 insulation on the interior side of the vapor retarder and R-9 insulation on the exterior side to reduce condensation in both the summer and the winter months. A further analysis of the temperatures of the vapor retarder compared to the dew point temperatures determines that the placement of R-5 insulation on the interior side and R-8 insulation on the exterior side also reduces condensation in both the winter and the summer.

Although the above description considers two temperature extremes, namely, summer and winter, for a given climate, if a more detailed analysis is desired, daily or hourly climatic data may be obtained and calculated, preferably with the aid of a computer program. In such a computer program, annual climatic data for a given location and the thermal properties of the insulation system (e.g., R-value, heat capacity, vapor permeance, internal dew point temperature, etc.) may be input and the condensation potential calculated for any length of time. In a preferred embodiment, the computer program would also factor in the benefit of the drying potential resulting from the reversal of the vapor drive from summer to winter and vice versa.

Although it is preferred that the placement of the vapor retarder eliminate the potential for condensation throughout the year, it is possible that in some geographic locations, the placement of the vapor retarder, may result in a small amount of condensation within the insulation at some point during the year. Because the inventive insulation system contains one vapor retarder between two layers of insulation, this small amount of condensation is able to dry out of the insulation as the vapor drive changes from the exterior to the interior of the building in the summer and from the interior to the exterior of the building in the winter.

In a preferred embodiment, an analysis of the amount of daily condensation that occurs is conducted. The amount of condensation that may occur within the insulation system depends on the temperature difference between the dew point temperature and the vapor retarder temperature and the length of time that the temperature of the vapor retarder is below the dew point temperature (i.e., the length of time that the condensation occurs). For example, for a particular geographic location, the placement of the vapor retarder may result in the temperature of the vapor retarder being 5° F. below the dew point temperature for 8 hours in one day. Thus, the condensation potential for this location would be 40° F.·hour (8 hours·5° F.). If the vapor retarder is placed at a location where the temperature is 2° F. below the dew point temperature for 4 hours, the condensation potential becomes 8° F.·hour (4 hours·2° F.). Therefore, by positioning the vapor retarder within the insulation so that amount of time that the temperature of the vapor retarder is below the dew point temperature is reduced, the amount of condensation will also be reduced.

By continuing the analysis of the condensation potential for the insulation system 24 hours a day for 365 days, the total condensation potential for the entire year for a given vapor retarder position may be determined for a given climate. This condensation potential may then be quantitatively compared to the condensation potentials for vapor retarders at other positions within the insulation system and an optimum location for the vapor retarder at that geographic location may be determined which reduces the overall condensation potential of the insulation system over an entire year for that given geographical location. A computer program may be used to conduct these calculations. Preferably, the computer program factors in the drying potential resulting from the reversal of the vapor drive, the transient effects of changing exterior temperature and humidity, the variation of the interior temperature and humidity throughout the year, the effects of solar load on the insulation system, and the moisture diffusion properties of the insulation and the vapor retarder.

An exemplary embodiment of an insulation system according to the present invention is illustrated in FIGS. 1a-6b. In particular, FIGS. 1a-6b illustrate the application of an insulation system of the present invention to a masonry wall. Although a masonry wall is used as one example for the application of the inventive insulation system, any wall that does not provide substantial thermal insulation could be utilized. In FIGS. 1a and 1b, the masonry wall is a concrete block wall 10. However, the wall could also be poured concrete, or any other suitable building material including stud framing. A plate 20 and joists 30 are shown for illustrative purposes to place the masonry wall in context with the framing structure.

Turning to FIGS. 2a-2b, a first layer of insulation 50 having a first thickness determined by the analysis described above is affixed to the concrete block wall 10. Any suitable mechanical fasteners (e.g., concrete nails) or adhesives may be used to fasten the first layer of insulation 50 to the concrete block wall 10. The first layer of insulation 50 may be any type of insulation known to those of skill in the art, such as, but not limited to, fiberglass insulation, a fiberglass board, rock wool glass board, or a mineral board. In a preferred embodiment, the first layer of insulation 50 is a foam board or high density fiberglass insulation that has sufficient strength and durability to support a vapor retarder 60 and a subsequent layer of insulation. The foam may be formed of extruded polystyrene, molded polystyrene, polyisocyanurate, phenolic foam, polyurethane, or other similar foam insulations identified by one of skill in the art.

The first layer of insulation 50 may be applied in a step-wise fashion, as illustrated in FIG. 2a and 3a, until the concrete block wall 10 is covered by the first layer of insulation 50 (not shown). As shown in FIG. 2b, the first layer of insulation 50 may include a vapor retarder 60. Alternatively, the vapor retarder 60 may be applied to the first layer of insulation 50 after the first layer of insulation 50 has been affixed to the concrete block wall 10 (not shown). When the vapor retarder 60 is pre-applied to the first layer of insulation 50, or if the first insulation layer has inherent vapor retarder properties (such as extruded polystyrene), such as is illustrated in FIG. 2b, the joints between first insulation layers 50 may be sealed by tape 61 or caulk (not shown) to form a substantially continuous vapor retarder. The vapor retarder 60 may be a sheet of plastic film (e.g., polyethylene, nylon, or a rubber membrane (EPDM)) or a foil (e.g., aluminum foil)) having a low vapor permeance.

Next, lineals 70 may be vertically and horizontally affixed to the vapor retarder 60 as depicted in FIGS. 4a and 4b, and are preferably spaced along the vapor retarder 60 to form insulation spaces that are substantially equal to the size of the second layer of insulation. Preferably, the lineals 70 are spaced approximately every 4 feet vertically across the concrete block wall 10. Optionally, lineals 70a may be affixed horizontally across the concrete block wall 10 as shown in FIGS. 4a-4b to provide an optional trim such as a chair rail or the like. The lineals 70a may have a structure that is identical to lineals 70 illustrated in FIG. 5a.

As shown in FIG. 5a, the lineal 70 is formed of a base member 71 and two vertically projecting arms 72. The base member 71 of the lineal 70 is affixed to the vapor retarder 60 by any suitable mechanical fastening devices, such as, but not limited to, nails and screws, or adhesives such that the arms 72 project inwardly from the vapor retarder 60. The lineals 70, 70a may be affixed to the concrete block wall 10 through the vapor retarder 60 and the first layer of insulation 50. Alternatively, the lineals 70, 70a may be affixed to the vapor retarder 60 via an adhesive.

Turning now to FIGS. 6a and 6b, a second layer of insulation 80 having a second thickness as determined by the analysis described above is placed in the insulation space formed by the lineals 70 adjacent to the vapor retarder 60. It is to be noted that the arms 72 of the lineals 70, 70a may vary in length to correspond to the thickness of the second insulation layer 80. The second layer of insulation 80 may be a high density fiberglass board, and may be the same or different than the first layer of insulation 50.

Preferably, the second layer of insulation 80 contains a permeable finished surface that provides an aesthetic appearance and which meets functional requirements such as damage resistance and fire resistance. If the second layer of insulation 80 does not contain a finished surface, a separate finished surface (not shown) may be attached to the second layer of insulation 80. However, such a separate finished surface requires an additional step of attaching the finished surface to the second layer of insulation 80. It is preferable that the finished surface does not act as a second vapor retarder which would trap moisture within the insulation system. A fire resistant fabric covering is a preferred finished surface because it provides an aesthetic and durable covering that is highly permeable. Preferably, the fabric is a polyolefin woven fabric having a basis weight of 1.3 oz/ft² with an integral Teflon surface treatment and a porous acrylic latex coating having a basis weight of 0.37 oz/ft² on the backside of the fabric. Further suitable examples of a decorative, permeable finished surface include, but are not limited to, woven polymers, glass mats (e.g., fiberglass mats), glass veils, non-woven polymers, and woven polyolefins.

To complete the insulation system, a trim piece 85 is attached to the lineals 70 over the finished surface. Suitable examples of trim pieces 85 are illustrated in FIGS. 5b-5f. For example, 5b depicts an outside corner trim piece 73, 5c depicts a cove 74, 5d depicts a batten 75, 5e depicts a base 76, and 5f depicts a casing 77. Battens 75 may be placed in the lineals 70 that are positioned vertically on the vapor retarder 60 to hold the second layer of insulation 80 in place. The cove 74, the base 76, and the casing 77 may be positioned in the lineals 70, 70a depending upon the desired aesthetic appearance. Each of the trim pieces 85, e.g., the outside corner trim piece 73, the cove 74, the batten 75, the base 76, and the casing 77, contain a flange member 78. To attach the trim piece 85 to the lineal 70, 70a, the flange member 78 is inserted between the two arms 72 and snapped into place. Such interlocking construction provides for easy and quick installation. 100601 In one embodiment of the present invention, the insulation system may be provided in modular insulation members with one modular insulation member containing a vapor retarder. An illustrative example of an insulation system formed of modular insulation members is set forth in FIGS. 7a-7d. In the illustrative example shown in FIGS. 7a-7d, the total amount of insulation present in the insulation system is divided into four modular members of substantially the same thickness, namely a first modular insulation member 81 that contains the vapor retarder 60, a second modular insulation member 82, a third modular insulation member 83, and a fourth modular insulation member 84. The total thickness of each of the modular insulation members 81, 82, 83, and 84 corresponds to the total R-value of the insulation. It is to be noted that the illustrative example set forth in FIGS. 7a-7d contain four modular members for ease of discussion. However, any number of modular members may be present in the insulation system depending on how many locations for the vapor retarder are desired within the insulation system. For example, if R-13 insulation is used in the insulation system, it may be desirable to form thirteen modular insulation members, each modular insulation member being substantially equal to each R-value of insulation. Such a division of the insulation would provide 14 optional positions for the vapor retarder (i.e., an interior position, an exterior position, and 12 interior positions).

Turning back to FIGS. 7a-7d, it can be seen that the modular members may be placed in any order to place the vapor retarder 60 at a desired location within the insulation. For example, if the analysis set forth above determines that the preferred location for the vapor retarder 60 is located substantially at the center of the insulation, such as is shown in FIG. 7a, the second modular insulation member 82 (or any modular insulation member that does not contain the vapor retarder 60) may be placed on the concrete block wall 10. The first modular insulation member 81 is then placed such that the vapor retarder 60 is positioned toward the interior of the building. The lineals 70, 70a may then be attached to the vapor retarder 60. The remaining modular insulation members 83, 84 may be sequentially placed over the vapor retarder 60 in the insulation spaces formed by the lineals 70, 70a. Trim pieces 85 may then be attached to complete the insulation system.

As shown in FIGS. 7b-7d, the vapor retarder 60 may be positioned at other incremental locations by placing the modular members on the concrete block wall 10 in various orders. In FIG. 7b, the vapor retarder is positioned with the vapor retarder 60 located off-center towards the interior of the building with a majority of the insulation towards the exterior such as, for example, by placing modular insulation members 82, 83, sequentially on the concrete block wall 10. The first modular insulation member 81 is then placed on modular insulation member 83 with the vapor retarder 60 facing the interior of the building. The lineals 70, 70a may then be attached to the vapor retarder 60 and the fourth modular insulation member 84 is placed in the insulation spaces formed by the lineals 70, 70a. FIG. 7c illustrates an example of the placement of the vapor retarder 60 on the exterior adjacent to the concrete block wall 10. To place the vapor retarder 60 on the concrete block wall 10, the first modular insulation member 81 is oriented with the vapor retarder 60 facing the exterior of the building. This orientation of the first modular member 81 is opposite than the orientation of the first modular insulation member 81 depicted in FIGS. 7a, 7b, and 7d. FIG. 7d illustrates an example of the positioning of the vapor retarder 60 off-center towards the exterior of the building with a majority of the insulation towards the interior of the building.

Such modular insulation systems such as are described above may be pre-packaged to include the modular insulation members, lineals, trim pieces, and instructions for assembling the modular insulation members to place the vapor retarder at the optimal location for a particular geographic climate.

Having generally described this invention, a further understanding can be obtained by reference to certain specific examples illustrated below which are provided for purposes of illustration only and are not intended to be all inclusive or limiting unless otherwise specified.

EXAMPLE

Determination of the Optimal Placement of a Vapor Retarder in Columbus, Ohio Based on Condensation Potential

Five separate experimental insulation systems are constructed in Columbus, Ohio, each experimental system having R-13 insulation placed a concrete block wall with a vapor retarder placed on or within the insulation at a chosen location. Each of the five experimental insulation systems are discussed in detail below and are shown schematically in FIGS. 8a, 9a, 10a, 11a, and 12a. The interior of the building for each of the experimental systems has a temperature of 65° F. and a relative humidity of 40%.

The outside temperature and the outside dew point temperature on both Jan. 1, 2002 and Aug. 1, 2002 are obtained, such as from hourly climatic data, and the temperature of the vapor retarders in each of the experimental systems are calculated. Graphs for the data for each of the five experimental systems are depicted in FIGS. 8b-8c, 9b-9c, 10b-10c, 11b-11c, and 12b-12c. In each of the graphs, the outside temperature is represented by a dotted line 92, the dew point temperature is depicted by a solid line 94, and the vapor retarder temperature is illustrated by a phantom line 96.

Experimental Insulation System 1

In Experimental Insulation System 1, shown in FIG. 8a, a layer of R-13 insulation 90 is placed on a concrete block wall 100 in a residential building. A vapor retarder 110 is affixed to the R-13 insulation 90 toward the interior of the building. In this experimental system, the vapor retarder 110 is placed in the “warm in winter” side of the insulation system with all of the insulation towards the exterior of the building.

A graphical analysis of the outside temperature, the outside dew point temperature, and the temperature of the vapor retarder 110 vs. the time of day for Aug. 1, 2002 is shown in FIG. 8b. Because the vapor retarder 110 is located toward the interior of the building, the temperature of the vapor retarder 110 remains substantially constant at 65° F. (the interior temperature). As illustrated in FIG. 8b, when the temperature of the vapor retarder 110 (phantom line 96) is less than the outside dew point temperature (solid line 94), condensation occurs. In FIG. 8b, condensation is depicted by the hashed regions. The condensation potential for each hour is the amount of the difference between the vapor retarder temperature and the dew point temperature (e.g., Δtemperature·hour). Thus, the total condensation potential for one day is calculated by adding the individual hourly condensation potentials over a twenty-four hour period. From the data obtained, the condensation potential is calculated to be 56.9° F.·hour.

A graphical analysis of the outside temperature, the outside dew point temperature, and the temperature of the vapor retarder 110 vs. the time of day for Jan. 1, 2002 is shown in FIG. 8c. As illustrated in FIG. 8c, the temperature for the vapor retarder 110 (phantom line 96) remains above the dew point temperature (solid line 94) for the entire time period. Consequently, no condensation occurs. Thus, the condensation potential on Jan. 1, 2002 is zero. The total condensation potential for both Aug. 1, 2002 and Jan. 1, 2002 is 56.9° F.·hour.

Experimental Insulation System 2

In Experimental Insulation System 2, shown in FIG. 9a, a first layer of R-9 insulation 120 is placed on a concrete block wall 100 in a residential building. A vapor retarder 110 is affixed to the first layer of R-9 insulation 120 toward the interior of the building. A second layer of R-4 insulation 130 is affixed to the vapor retarder 110, thus placing the vapor retarder 110 between the two layers of insulation. As can be seen in FIG. 9a, the vapor retarder 110 is positioned off-center towards the interior of the building. As in Experimental Insulation System 1, the total insulation in the system is R-13.

Graphical analyses of the outside temperatures, the outside dew point temperatures, and the temperatures of the vapor retarder 110 vs. the time of day for Aug. 1, 2002 and Jan. 1, 2002 are depicted in FIGS. 9b and 9c respectively. As shown in FIG. 9b, the vapor retarder temperature (phantom line 96) is below the outside dew point temperature (solid line 94) during the early morning. This is when the condensation occurs. The condensation potential for Aug. 1, 2002 is calculated to be 21.0° F.·hour. Because the temperature of the vapor retarder does not drop below the outside dew point temperature on Jan. 1, 2002, no condensation occurs, as is illustrated in FIG. 9c. Thus, there is no condensation potential. The total condensation potential for both Aug. 1, 2002 and Jan. 1, 2002 is 21.0° F.·hour.

Experimental Insulation System 3

In Experimental Insulation System 3, shown in FIG. 10a, a first layer of R-6.5 insulation 140 is placed on a concrete block wall 100 in a residential building. A vapor retarder 110 is affixed to the first layer of R-6.5 insulation 140 toward the interior of the building. A second layer of R-6.5 insulation 150 is affixed to the vapor retarder 110, thus placing the vapor retarder 110 between two equal layers of insulation. The total insulation in the system is R-13.

Graphical analyses of the outside temperatures, the outside dew point temperatures, and the temperatures of the vapor retarder 110 vs. the time of day for Aug. 1, 2002 and Jan. 1, 2002 are depicted in FIGS. 10b and 10c respectively. As seen in FIGS. 10b and 10c, there is slight condensation in the early morning hours for both days. The condensation potential for Aug. 1, 2002 is calculated to be 7.5° F.·hour and the condensation potential for Jan. 1, 2002 is calculated to be 8.0° F.·hour. Thus, the total condensation potential for both Aug. 1, 2002 and Jan. 1, 2002 is 15.5° F.·hour.

Experimental Insulation System 4

In Experimental Insulation System 4, shown in FIG. 11a, a first layer of R-4 insulation 160 is placed on a concrete block wall 100 in a residential building. A vapor retarder 110 is affixed to the first layer of R-4 insulation 160 toward the interior of the building. A second layer of R-9 insulation 170 is affixed to the vapor retarder 110, thus placing the vapor retarder 110 between the two layers of insulation. As shown in FIG. 11a, the vapor retarder 110 is positioned off-center towards the exterior of the building. The total insulation in the system is R-13.

Graphical analyses of the outside temperatures, the outside dew point temperatures, and the temperatures of the vapor retarder 110 vs. the time of day for Aug. 1, 2002 and Jan. 1, 2002 are depicted in FIGS. 11b and 11c respectively. As shown in FIG. 11b, there is very slight condensation in the early morning hours on Aug. 1, 2002. The condensation potential is calculated to be 1.0° F.·hour. Because the vapor retarder temperature (phantom line 96) is below the outside dew point temperature (solid line 94) for the entire day, there is a large amount of condensation on Jan. 1, 2002 (FIG. 11c). The condensation potential for Jan. 1, 2002 is calculated to be 131.5° F.·hour. Adding the condensation potentials for both days yields a total condensation potential of 132.5° F.·hour.

Experimental Insulation System 5

In Experimental Insulation System 5, shown in FIG. 12a, a vapor retarder 110 is placed directly on a concrete block wall 100 and covered with a layer of R-13 insulation 180. In this experimental system, the vapor retarder 110 is placed in the “warm in summer” side of the insulation system with all of the insulation towards the interior of the building.

Graphical analyses of the outside temperatures, the outside dew point temperatures, and the temperatures of the vapor retarder 110 vs. the time of day for Aug. 1, 2002 and Jan. 1, 2002 are depicted in FIGS. 12b and 12c respectively. On Aug. 1, 2002, the temperature of the vapor retarder 110 (phantom line 96) remains above the dew point temperature (solid line 94). As a result, no condensation occurs and the condensation potential is zero (FIG. 12b). As shown in FIG. 12c, the temperature of the vapor retarder 110 is below the outside dew point temperature for the entire day on Jan. 1, 2002, resulting in severe condensation. The condensation potential is calculated to be 424.9° F.·hour. Adding the condensation potentials for both days yields a total condensation potential of 424.9° F.·hour.

Comparing the total condensation potentials for each of the five experimental systems, it is determined that Experimental Insulation System 3 has the lowest total condensation potential. Thus, in Columbus, Ohio, the optimal location for the vapor retarder 110 in R-13 insulation is near the mid-point, such as with R-6.5 insulation positioned on both sides of the vapor retarder. Experimental Insulation System 2 had a total condensation potential that is slightly greater than Experimental Insulation System 3. Thus, the vapor retarder 110 may alternatively be placed with R-4 insulation to the exterior and R-9 insulation to the exterior of the vapor retarder 110.

The invention of this application has been described above both generically and with regard to specific embodiments. Although the invention has been set forth in what is believed to be the preferred embodiments, a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure. The invention is not otherwise limited, except for the recitation of the claims set forth below.

Claims

1. A method for positioning a vapor retarder within an insulation system at a geographic location to reduce condensation within said insulation system comprising: determining an incremental change in temperature per R-value of insulation within said insulation system at said geographic location; calculating a location within said insulation system where the temperature of said insulation is above a dew point temperature using said incremental change in temperature; and positioning said vapor retarder at said location.

2. The method of claim 1, wherein said determining step comprises: calculating a temperature differential between an exterior temperature at said geographic location and a corresponding interior temperature where said insulation system is to be placed; and dividing said temperature differential by the total R-value of said insulation to obtain said incremental change in temperature.

3. The method of claim 1, wherein said positioning step comprises: affixing a first layer of insulation to a wall such that said first layer of insulation has a thickness that positions an inner surface of said first layer of insulation at said location; attaching said vapor retarder to said inner surface of said first layer of insulation; and placing a second layer of insulation on said first layer of insulation so that said vapor retarder is positioned between said first and second layers of insulation.

4. The method of claim 3, wherein said placing step comprises: attaching lineals to said vapor retarder to create at least one insulation space; placing said second layer of insulation adjacent to said vapor retarder, said second layer of insulation being positioned within said at least one insulation space; and affixing at least one trim piece to said lineals.

5. The method of claim 4, wherein said at least one trim piece retains said second layer of insulation within said at least one insulation space.

6. The method of claim 1, wherein said vapor retarder has a temperature above an exterior dew point temperature in the summer and above an interior dew point temperature in the winter at said geographic location.

7. The method of claim 1, further comprising: determining condensation potentials for said insulation system at incremental locations within said insulation system; and placing the vapor retarder at the incremental location within said insulation system that produces the least amount of condensation within the insulation system.

8. An insulation system comprising: a first layer of insulation having a first thickness affixed to a wall; a vapor retarder positioned on said first layer of insulation; lineals positioned on said vapor retarder to create at least one insulation space; a second layer of insulation having a second thickness affixed to said vapor retarder and positioned within said insulation space; and at least one trim piece affixed to said lineal.

9. The insulation system of claim 8, wherein said lineals are affixed to said wall through said vapor retarder and first layer of insulation.

10. The insulation system of claim 8, wherein said lineals are adhered to said vapor retarder.

11. The insulation system of claim 8, wherein said first layer of insulation is a foam board.

12. The insulation system of claim 8, wherein said vapor retarder is pre-applied to said first layer of insulation.

13. The insulation system of claim 8, wherein said second layer of insulation includes a finished surface that provides an aesthetic appearance.

14. The insulation system of claim 13, wherein said finished surface is a decorative, permeable layer selected from the group consisting of a woven polymer, a glass, mat, a glass veil, a non-woven polymer and a woven polyolefin.

15. The insulation system of claim 8, wherein said at least one trim piece retains said second layer of insulation within said insulation space.

16. The insulation system of claim 8, wherein each of said first layer of insulation and said second layer of insulation are formed of at least one modular insulation member.

17. The insulation system of claim 16, wherein one of said at least one modular insulation member contains said vapor retarder.

18. The insulation system of claim 8, wherein said first thickness is determined by calculating a location within said insulation system where the temperature is above a dew point temperature, said location being defined as a first dimension from said wall, said first thickness being equal to said first dimension.

19. An insulation system comprising: a first layer of insulation having a first thickness affixed to a wall, said first thickness being calculated by determining a location within said insulation system where the temperature is above a dew point temperature, said location being defined as a first dimension from said wall and said first thickness being equal to said first dimension; a vapor retarder positioned on said first layer of insulation; and a second layer of insulation having a second thickness affixed to said vapor retarder.

20. The insulation system of claim 19, wherein said first layer of insulation is a foam board.

21. The insulation system of claim 19, wherein said vapor retarder is pre-applied to said first layer of insulation.

22. The insulation system of claim 19, further comprising lineals positioned on said vapor retarder to create at least one insulation space.

23. The insulation system of claim 22, further comprising at least one trim piece that retains said second layer of insulation within said insulation space.

24. The insulation system of claim 19, wherein said second layer of insulation includes a decorative, permeable layer selected from the group consisting of a woven polymer, a glass mat, a glass veil, a non-woven polymer and a woven polyolefin.

25. The insulation system of claim 19, wherein both of said first layer of insulation and said second layer of insulation are formed of at least one modular insulation member.

26. The insulation system of claim 25, wherein one of said at least one modular insulation member contains said vapor retarder.

27. A method of installing an insulation system having an R-value and a variably positioned vapor retarder on a wall comprising: determining an incremental change in temperature per R-value of insulation for said insulation system; calculating a location within the insulation system where the temperature is above a dew point temperature using said incremental change in temperature, said location being defined as a first dimension from said wall; affixing a first layer of insulation having a first thickness equal to said first dimension onto said wall; positioning said vapor retarder on said first layer of insulation; attaching lineals to said vapor retarder to create at least one insulation space; placing a second layer of insulation in said at least one insulation space adjacent to said vapor retarder; and connecting at least one trim piece to said lineals.

28. The method of claim 27, further comprising taping joints located between adjoining first layers of insulation to form a substantially continuous vapor retarder.