US20080304921A1

US20080304921A1 - Micro-climate crawl space system

Info

Publication number: US20080304921A1
Application number: US12/135,149
Authority: US
Inventors: Ron F. Langley
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-06-08
Filing date: 2008-06-07
Publication date: 2008-12-11

Abstract

A micro-climate crawl space system having a means for keeping water from entering the crawl space, a means of expelling water that enters the crawl space, a means for keeping water vapor from entering the crawl space, a means of expelling water vapor from the crawl space, and a means for minimizing the deleterious impact of water that is present in the crawl space. The means of expelling water is a durable thermal insulating sealing apparatus, where the apparatus isolates the crawl space; and a supply of conditioned air that is typically drawn from an interior of the building, where the conditioned air is supplied at a rate sufficient to effect a slight positive pressure on the crawl space.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present non-provisional patent application claims priority to U.S. Provisional Patent Application Ser. No. 60/933,881, filed Jun. 8, 2007, and entitled “MICRO-CLIMATE CRAWL SPACE SYSTEM,” which is incorporated in full by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to systems for keeping a crawl space dry, and more particularly to a system that controls the temperature and humidity in the crawl space, and prevents moisture from moving through foundation walls to the sill, therein reducing damage caused by dry rot, termites, vermin, mold, fungus, and the like.

BACKGROUND OF THE INVENTION

There are many buildings and homes built without basements, where the floor is elevated a few feet above the ground on a foundation wall composed of stone, poured concrete or concrete block walls. The crawl space between the ground surface and the sub-flooring typically includes wooden floor beams or joists of the building, and the floor of the crawl space is typically near or below the grade level of the surrounding soil, so that when wet, water flows into and is absorbed up through the floor of the crawlspace. Traditionally, the crawl space floor usually is just a dirt floor. Additionally, water in contact with the foundation wall permeates and disperses throughout the wall via a variety of mechanisms (e.g., capillary action, diffusion, and the like). The heat capacity of materials in the foundation walls is always higher than the heat capacity of air, so the walls are usually cooler or warmer than the air, because they are slower to change temperature than the air. This creates a temperature differential between the air and the foundation walls. A consequence of this difference in temperature is that moisture collects on the walls when they are cooler than the air, and then releases water vapor when the walls are warmer than the ambient temperature. Depending on how the crawl space is conditioned, the crawl space air temperature and humidity can be similar to the outside air, or more like the air on the inside of the building. If the crawl space is vented, the air is going to be more like the outside air, than if the crawl space is closed, because there is a greater exchange of air and the air typically is not conditioned. This and other factors can have a significant impact on what happens to the moisture in the foundation walls. Other factors that influence the moisture and temperature in the crawl space include whether the walls are insulated, and if and how the walls are sealed.
Moisture in the headroom of the crawl space in the form of water vapor will penetrate the wooden structural members of the building, causing wood rot, mold, odors, attraction of ants and other insects, rodents etc. Mold spores exist in air and grow into destructive mold in the presence of organic material, such as moist wood. Humidity levels of from 50% to 90% are common in crawl spaces. Mold can grow on dirt, insulation, wood framing and even under carpeting on the floor within the home. Mold digests and destroys organic material as it feeds on it. Damp environments also provide an inviting environment for insects such as termites, ants and other insects which feed on moist organic material (i.e. a wood sub-flooring), and can contribute to the destruction and collapse thereof.
In an effort to prevent the penetration of water and water vapor into building crawl spaces it has been proposed to apply a continuous moisture barrier layer such as a 6 mil. thick plastic film over the dirt floor of the crawl space. This has been proven to be unsatisfactory, per se, since water is drawn up from the ground, beneath the barrier, and leaks and/or vaporizes around the edges of the barrier into the crawl space environment. Also, ground water penetrates the walls of the crawl space and/or otherwise enters the crawl space and accumulates on top of the vapor barrier film and generates moisture which permeates into the wooden structural supports of the building resulting in rot and decay, mold and fungus, odors and vermin. Also a 6 mil vapor barrier film is not sufficiently durable to resist tearing and being punctured under the stress and weight of a workman crawling on it.
U.S. Pat. No. 5,642,967 discloses a system in which the barrier film is associated with an excavated pit filled with aggregate. Water entering the crawl space collects in the pit and is pumped from a sump when necessary. A vapor barrier film is applied over the dirt floor of the crawl space, and over the pit and sump areas, to prevent moisture from entering the building. Such a system is unsatisfactory because it has no mechanism for preventing the entry of ground water and its accumulation on the surface of the barrier film, with the disadvantages discussed supra.
U.S. Pat. No. 5,890,845 discloses another system in which the dirt floor of a crawl space is covered with a layer of lightweight concrete material applied over a plastic film barrier layer. While the barrier layer blocks the penetration of moisture from the ground up into the crawlspace, the system provides no mechanism for preventing the entry of ground water through the walls of the crawl space onto the surface of the concrete material where it can accumulate in surface depressions and develop moisture, with the disadvantages discussed above.
U.S. Pat. No. 6,575,666 discloses a system which prevents the entry of water from the sub-soil and also from higher elevations of the surrounding ground, such as excessive ground water caused by rain, snow and/or flooding, into crawl spaces directly or through the concrete block walls which surround and enclose the crawl space. The system of U.S. Pat. No. 6,575,666 includes applying over the floor of the crawl space, generally a dirt floor but sometimes a poured concrete floor, a continuous sealed plastic film barrier layer, and extending the barrier film vertically-upwardly to cover and seal the interior peripheral walls enclosing the crawl space to an elevation at least slightly greater than the elevation of the ground in contact with the exterior surfaces of the peripheral walls and preferably to the tops of the peripheral walls. This encapsulates the dirt surface of the entire crawl space against the penetration of external ground water or flood water and also sub-soil water and water vapor onto the surface of the plastic barrier film and into the crawl space atmosphere. Applicant has found that a down side to this system is that water is still drawn up through the foundation walls, resulting in moisture in the sub-flooring.
While the system of U.S. Pat. No. 6,575,666 represents a substantial improvement in the waterproofing of crawl spaces, there remains a need for an improved system which further insulates the barrier layer against rupturing or tearing and a system which accommodates for water migrating up through the foundation walls.
The present invention relates to a crawl space waterproofing system which is a comprehensive system that provides a micro-climate in the crawl space, and further provides prophylactic measures to occlude water and water vapor from entering the crawl space.

BRIEF SUMMARY OF THE INVENTION

In various exemplary embodiments, the present invention provides a micro-climate crawl space system including a durable thermal insulating sealing apparatus, where the apparatus isolates the crawl space; and a supply of conditioned air that is typically drawn from an interior of the building, where the conditioned air is supplied at a rate sufficient to effect a slight positive pressure on the crawl space. The micro-climate crawl space system, in addition to insulating the crawl space against transfer of heat, also prevents moisture from moving up through the walls around the foundation, where the moisture would penetrate the wooden structural members of the building's sub-flooring. Keeping wooden structural members dry substantially eliminates dry rot, termites, and most forms of mildew, thus extending the life of the building, and lowering the cost of maintaining and operating the building. An added benefit is that the building's floor above the crawl space stays at a temperature that is comparable to the air temperature in the building, as the air temperature in the crawl space and above the floor are at approximately the same temperature.
The durable thermal insulating sealing apparatus is mounted on and covers substantially all of the vertical surface area of the interior side of the foundation walls, where the vertical surface area is the perimeter and height of the crawl space. When mounted, the apparatus forms an insulated reflective chamber comprised of a plurality of substantially parallel furring strips of insulation covered with a reflective sheet reflectively facing the interior side of wall. The reflective sheet is protected, for instance, with an over-sheet of reinforced liner and the like that extends to and can be coextensive with a barrier liner that covers the crawl space floor. The furring strips, reflective sheet and the reinforced liner are affixed to the foundation wall with multiple fastening elements, such staples, nails or screws, which can be used to simultaneously form and attach the insulated reflective chamber. The insulated reflective chamber reflects radiant heat emanating from the foundation wall back into the chamber, raising the temperature of the chamber, lowering the relative humidity, and increasing the difference between the dew point and the temperature of the air in the chamber. This keeps moisture in the form of a vapor, which exerts pressure on the wall, therein driving moisture towards the outside. The slight positive pressure on the crawl space augments the movement of water vapor towards the outside. The crawl space is maintained dry, as the cumulative effect of all the insulated reflective chambers, act as a static moisture pump to expel water vapor from the crawl space.
In an exemplary embodiment, a climate crawl space system includes a foundation wall forming a crawl space; a barrier liner covering a crawl space floor; and a durable thermal insulating sealing apparatus mounted on and substantially covering a vertical surface area of an interior side of the foundation wall, wherein the durable thermal insulating sealing apparatus provides a mechanism for expelling water vapor from the crawl space. The climate crawl space system can further include an exterior water proofing membrane sealing an exterior side of the foundation wall. Optionally, the climate crawl space system further includes a drain system including a collection drain and pipes operable to divert water away from the exterior water proofing membrane. The barrier liner can include a reinforced poly-liner having a thickness of 10 to 20 mils. Optionally, the poly-liner includes one of polyolefins, polyvinylchorides, etheylene propylene diene-monomers, ethylenepropylenes, and chlorinated polyethylenes.
The climate crawl space system can further include an interior emergency collection apparatus located on the crawl space floor. The interior emergency collection apparatus includes one of a drain and a sump pump, and the interior emergency collection apparatus further includes an alarm and a backflow sensor. The climate crawl space system can further include a fan configured to supply conditioned air from an interior of a building. The fan is configured to supply the conditioned air at a rate sufficient to affect a slight positive pressure on the crawl space. The durable thermal insulating sealing apparatus can include a plurality of substantially parallel furring strips of insulation covered with a reflective sheet reflectively facing the interior side of the foundation wall. The durable thermal insulating sealing apparatus can further include an insulated reflective chamber covered with a reinforced filmic liner. The reinforced filmic liner extends to and is coextensive with the barrier liner. Optionally, the plurality of substantially parallel furring strips include strips of polystyrene foam insulation with an R value of the polystyrene foam insulation of about 7-10. Alternatively, the reflective sheet includes an R value of about 7. The insulated reflective chamber reflects radiant heat emanating from the foundation wall back into the reflective chamber thereby raising the temperature of the reflective chamber, lowering the relative humidity, and increasing the difference between the dew point and the temperature of the air in the reflective chamber keeping moisture in the form of a vapor, which exerts pressure on the foundation wall therein driving moisture towards the outside. Optionally, the climate crawl space system of further includes a sill seal capping the foundation wall; and an application of lacquers and antimicrobial antifungal coatings to protect a sub-flooring.
In another exemplary embodiment, a crawl space of a building includes foundation walls; a barrier liner covering a crawl space floor; a durable thermal insulating sealing apparatus mounted on and substantially covering a vertical surface area of an interior side of the foundation walls, wherein the durable thermal insulating sealing apparatus provides a mechanism for expelling water vapor from the crawl space; an interior emergency collection apparatus located on the crawl space floor; and a fan configured to supply conditioned air from an interior of a building; wherein the durable thermal insulating sealing apparatus includes a plurality of substantially parallel furring strips of insulation covered with a reflective sheet reflectively facing the interior side of the foundation walls; wherein the durable thermal insulating sealing apparatus further includes an insulated reflective chamber covered with a reinforced filmic liner; and wherein the reinforced filmic liner extends to and is coextensive with the barrier liner.
In yet another exemplary embodiment, a micro-climate crawl space system includes a means for keeping water from entering a crawl space; a means for expelling water that has entered the crawl space; a means for keeping water vapor from entering the crawl space; a means for expelling water vapor from the crawl space; and a means for minimizing a deleterious impact of water that is present in the crawl space. Optionally, the means of expelling water vapor from the crawl space includes a durable thermal insulating sealing apparatus, wherein the apparatus isolates the crawl space; and a supply of conditioned air that is drawn from an interior of the building, wherein the conditioned air is supplied at a rate sufficient to effect a slight positive pressure on the crawl space. The durable thermal insulating sealing apparatus is an insulated reflective chamber including a plurality of substantially parallel furring strips of insulation covered with a reflective sheet reflectively facing an interior side of a foundation wall, and an over-sheet of reinforced filmic liner that extends to and is coextensive with a barrier liner covering the crawl space floor.
As will be apparent from the figures, the invented system in its broadest sense is comprised of a means for keeping water from entering the crawl space, a means of expelling water that enters the crawl space, a means for keeping water vapor from entering the crawl space, a means of expelling water vapor from the crawl space, and a means for minimizing the deleterious impact of water that is present in the crawl space.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated and described herein with reference to the various drawings, in which like reference numbers denote like system components, respectively, and in which:

FIG. 1 is a cut away view of the invented micro-climate crawl space system;

FIG. 2 is a planar view of the micro-climate crawl space system, wherein the building floor is not shown;

FIG. 3 is a cross-sectional side view of the durable thermal insulating sealing apparatus; and

FIG. 4 is a frontal view of the durable thermal insulating sealing apparatus having multiple chambers.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a micro-climate crawl space system for keeping water from entering the crawl space, a mechanism of expelling water that enters the crawl space, a mechanism for keeping water vapor from entering the crawl space, a mechanism of expelling water vapor from the crawl space, and a mechanism for minimizing the deleterious impact of water that is present in the crawl space. The present invention utilizes a thermal air break to eliminate capillary action in the foundation and reduce psychrometric condensation.
Referring to FIG. 1, a micro-climate crawl space system 10 equipped in a building crawl space 12 is illustrated with a ground level 14 higher than a crawl space floor 16 according to an exemplary embodiment of the present invention. The mechanism for keeping water from entering the crawl space 12 includes a foundation wall 20, typically constructed of cast or block concrete on a footer 22, and an exterior water proofing membrane 24. If the building has a veneer, particularly a brick veneer 26, then the exterior waterproofing membrane 24 is positioned against the brick 26. The exterior water proofing membrane 24 is impervious, and serves as a mechanism for keeping both water and water vapor from entering the crawl space 12. A drain system 30 including a collection drain and pipes 32 can divert water away from the exterior waterproofing membrane 24.
The mechanism for keeping water from entering the crawl space 12 can further include a barrier liner 40, which covers the crawl space floor 16 and a durable thermal insulating sealing apparatus 50. The durable thermal insulating sealing apparatus 50 provides a mechanism for expelling water vapor from the crawl space 12, and the apparatus 50 is mounted on and substantially covers a vertical surface area of an interior side of the foundation walls 20.
An example of the barrier liner 40 is a reinforced filmic liner, such as a scrim reinforced poly-liner having a thickness of 10 to 20 mils, with a preferred thickness of about 12 mils. The poly-liner is selected to have good weathering properties, such as polyolefins, polyvinylchorides, etheylene propylene diene-monomers, ethylenepropylenes, chlorinated polyethylenes, and the like. The crawl space floor 16 can be sloped to collect water in an interior emergency collection apparatus 54, which is one mechanism for expelling water from the crawl space 12. Examples of the interior emergency collection apparatus 54 are drains, sump pumps, and the like, where the collection apparatus 54 preferably further includes an alarm and a backflow sensor.
Referring to FIG. 2, the micro-climate crawl space system 10 has a planar area defined by the floor crawl space 12 enclosed within the perimeter of the foundation walls 20. The walls 20 have an interior vertical surface area defined as the product of a height and perimeter length of the foundation walls 20. The crawl space 12 volume is defined by the height of the walls 20 times the planar area enclosed by the perimeter foundation walls 20. The mechanism of expelling water vapor that is in the crawl space 12 includes the durable thermal insulating sealing apparatus 50 and a supply of conditioned air by a fan 60 that is typically drawn from an interior of the building. The durable thermal insulating sealing apparatus 50 is located the interior of the foundation walls 20. The conditioned air is supplied at a rate sufficient to affect a slight positive pressure on the crawl space 12. A guideline for a suitable fan 60 is one that blows about 1 cfm for every square foot of the building's sub-flooring. The fan draws air from the interior of the building. The flow rate produces a pressure of about 4-5 Pascal or (˜0.00058 psi or 0.016 inches water)-(˜0.00073 psi to 0.020 inches water). The micro-climate crawl space system 10 thermally insulates and prevents moisture from moving up through the foundation walls 20. A target temperature range is 58° F. to 72° F. with a relative humidity of 68% or less is desired. The dew point at these temperatures is 48° F. to 61° F., which is low enough that there will be very little condensation.
Referring to FIGS. 1 and 3-4, the mechanism of expelling water vapor from the crawl space 12 includes the durable thermal insulating sealing apparatus 50 mounted on and substantially covering the vertical surface area of the interior side 52 of the foundation walls 20. When mounted, the durable thermal insulating sealing apparatus 50 forms an insulated reflective chamber 60 which includes a plurality of substantially parallel furring strips 66 of insulation covered with a reflective sheet 62 reflectively facing the interior side 52 of the wall 50. The reflective sheet 62 is protected with an over-sheet of reinforced filmic liner 64 that extends to and is usually coextensive with the barrier liner 40, and in fact is typically the same material, covering the crawl space floor 16. The furring strips are typically about 1.5 inches thick strips of polystyrene foam insulation. The R value of the polystyrene foam insulation is about 7-10, with 8-9 being preferable. The reflective sheet 62 has an insulation value of about 7. The over-sheet of reinforced filmic liner 64 is about 12 mil thick. The furring strips 66, reflective sheet 62, and the reinforced filmic liner 64 are affixed to the foundation wall 50 with multiple fastening elements 70, such as staples, screws, nails, or the like.
The reinforced filmic liner 64 is normally wrapped around a top laterally running furring strip 66, and then draped down and fastened to a parallel strip beneath it forming the insulated reflective chamber 60. Depending on the vertical height of the foundation wall 20, there can be multiple furring strips 66 in the insulated reflective chamber 60 separated by a distance of about 4 to 12 inches. Vertical furring strips 66 are added as required to enclose the ends forming the insulated reflective chamber 60. The insulated reflective chamber 60 reflects radiant heat emanating from the foundation wall 20 back into the chamber 60, raising the temperature of the chamber 60, lowering the relative humidity, and increasing the difference between the dew point and the temperature of the air in the chamber 60. This keeps moisture in the form of a vapor, which exerts pressure on the wall 20, therein driving moisture towards the outside. The slight positive pressure on the crawl space 12 created by the fan 60 augments the movement of water vapor towards the outside. The crawl space 12 is maintained dry, as the cumulative effect of all the insulated reflective chambers 60, act as a static moisture pump to expel the water vapor from the crawl space 12.
The mechanism for minimizing the deleterious impact of water that is present in the crawl space 12 includes a sill seal 72 which caps the foundation walls 20, an application of lacquers and antimicrobial antifungal coatings which protect a sub-flooring 74, termite treatments, and a sub-flooring insulation 76. An example of the sub-flooring insulation 76 is a soft foam insulation and air barrier system such as Icynene's® water-blown foam insulation. The sub-flooring insulation 76 minimizes air leakage for increased energy efficiency, reduces noise and adheres to most construction materials. It is applied as a liquid, and expands its volume to fill cracks and crevices. The R-value is about 3.6 per inch. It acts as insulation and an air barrier to minimize air leakage and seal the building envelope for optimal air tightness. The outside of the sub-flooring 74 and the building is typically sealed with a wrap like Tyvek® a Dupont product. Additionally, a wrap 78 and flashing 80 may be used to seal the crawl space 12. The flashing 80 covers the sub-flooring 74, the foundation wall 20, and the brick 26. The wrap 78 is over the flashing 80.
Referring to FIG. 4, a relatively tall foundation wall 20 may require a wider durable thermal insulating sealing apparatus 50 according to an exemplary embodiment of the present invention. In the illustrated embodiment, there are three furring strips 66 spanned by the reflective sheet 62 and the reinforced filmic liner 64 forming two chambers 60. The reinforced filmic liner 64 is shown draping down, and typically is coextensive with the floors barrier liner.
Although the present invention has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended to be covered by the following claims.

Claims

1. A climate crawl space system, comprising:

a foundation wall forming a crawl space;

a barrier liner covering a crawl space floor; and

a durable thermal insulating sealing apparatus mounted on and substantially covering a vertical surface area of an interior side of the foundation wall, wherein the durable thermal insulating sealing apparatus provides a mechanism for expelling water vapor from the crawl space.

2. The climate crawl space system of claim 1, further comprising:

an exterior water proofing membrane sealing an exterior side of the foundation wall.

3. The climate crawl space system of claim 2, further comprising:

a drain system comprising a collection drain and pipes operable to divert water away from the exterior water proofing membrane.

4. The climate crawl space system of claim 1, wherein the barrier liner comprises a reinforced poly-liner having a thickness of 10 to 20 mils.

5. The climate crawl space system of claim 4, wherein the poly-liner comprises one of polyolefins, polyvinylchorides, etheylene propylene diene-monomers, ethylenepropylenes, and chlorinated polyethylenes.

6. The climate crawl space system of claim 1, further comprising:

an interior emergency collection apparatus located on the crawl space floor.

7. The climate crawl space system of claim 6, wherein the interior emergency collection apparatus comprises one of a drain and a sump pump, and wherein the interior emergency collection apparatus further comprises an alarm and a backflow sensor.

8. The climate crawl space system of claim 1, further comprising:

a fan configured to supply conditioned air from an interior of a building.

9. The climate crawl space system of claim 8, wherein the fan is configured to supply the conditioned air at a rate sufficient to affect a slight positive pressure on the crawl space.

10. The climate crawl space system of claim 1, wherein the durable thermal insulating sealing apparatus comprises a plurality of substantially parallel furring strips of insulation covered with a reflective sheet reflectively facing the interior side of the foundation wall.

11. The climate crawl space system of claim 10, wherein the durable thermal insulating sealing apparatus further comprises an insulated reflective chamber covered with a reinforced filmic liner.

12. The climate crawl space system of claim 11, wherein the reinforced filmic liner extends to and is coextensive with the barrier liner.

13. The climate crawl space system of claim 10, wherein the plurality of substantially parallel furring strips comprise strips of polystyrene foam insulation with an R value of the polystyrene foam insulation of about 7-10.

14. The climate crawl space system of claim 10, wherein the reflective sheet comprises an R value of about 7.

15. The climate crawl space system of claim 11, wherein the insulated reflective chamber reflects radiant heat emanating from the foundation wall back into the reflective chamber thereby raising the temperature of the reflective chamber, lowering the relative humidity, and increasing the difference between the dew point and the temperature of the air in the reflective chamber keeping moisture in the form of a vapor, which exerts pressure on the foundation wall therein driving moisture towards the outside.

16. The climate crawl space system of claim 1, further comprising:

a sill seal capping the foundation wall; and

an application of lacquers and antimicrobial antifungal coatings to protect a sub-flooring.

17. A crawl space of a building, comprising:

foundation walls;

a barrier liner covering a crawl space floor;

a durable thermal insulating sealing apparatus mounted on and substantially covering a vertical surface area of an interior side of the foundation walls, wherein the durable thermal insulating sealing apparatus provides a mechanism for expelling water vapor from the crawl space;

an interior emergency collection apparatus located on the crawl space floor; and

a fan configured to supply conditioned air from an interior of a building;

wherein the durable thermal insulating sealing apparatus comprises a plurality of substantially parallel furring strips of insulation covered with a reflective sheet reflectively facing the interior side of the foundation walls;

wherein the durable thermal insulating sealing apparatus further comprises an insulated reflective chamber covered with a reinforced filmic liner; and

wherein the reinforced filmic liner extends to and is coextensive with the barrier liner.

18. A micro-climate crawl space system comprising:

a means for keeping water from entering a crawl space;

a means for expelling water that has entered the crawl space;

a means for keeping water vapor from entering the crawl space;

a means for expelling water vapor from the crawl space; and

a means for minimizing a deleterious impact of water that is present in the crawl space.

19. The micro-climate crawl space system of claim 18, wherein the means of expelling water vapor from the crawl space comprises:

a durable thermal insulating sealing apparatus, wherein the apparatus isolates the crawl space; and

a supply of conditioned air that is drawn from an interior of the building, wherein the conditioned air is supplied at a rate sufficient to effect a slight positive pressure on the crawl space.

20. The micro-climate crawl space system of claim 19, wherein the durable thermal insulating sealing apparatus is an insulated reflective chamber comprised of a plurality of substantially parallel furring strips of insulation covered with a reflective sheet reflectively facing an interior side of a foundation wall, and an over-sheet of reinforced filmic liner that extends to and is coextensive with a barrier liner covering the crawl space floor.