Patent Application
20090183444
Buildings typically have a perimeter footing located in the ground below the frost line and an upstanding perimeter foundation supported thereon, the foundation typically lying both within and above the ground. Building side walls are supported then on the foundation above the ground level. A crawl space is frequently defined inside of the foundation perimeter underlying the joists (not shown) of the building first floor. Many crawl spaces have only a dirt floor and/or a dirt floor with an overlying layer of stones, and sometimes a thin overlying plastic sheet is spread over that. In seeking economy of building heating or cooling, and improved comfort levels, many resident buildings are constructed to minimize air leakage through the walls, doors, windows, etc.
Radon gas is an invisible, odorless and radioactive gas that occurs naturally from decaying uranium beneath the earth's surface, and escapes to the atmosphere under low pressures following paths of least resistance from many types of the earth surfaces. Of interest, the dirt floor of many common crawl spaces allow Radon gas discharge into the building, which being substantially sealed, allows possible Radon accumulation to significant levels that can become a health hazard to the occupants. In fact, the U.S. Environmental Protection Agency notes that Radon gas is the leading cause of lung cancer in non-smokers when it is repeatedly inhaled.
The present invention teaches, and a general object of this invention is to provide a system for precluding Radon gas naturally discharging from the ground from entering a building enclosure via a crawl space and building up to potentially harmful concentrations.
Detailed features of the invention include means to seal and/or isolated the crawl space ground/floor from the crawl space and/or building interior, and means to collect Radon gases being naturally discharged from the crawl space ground/floor before entering into the crawl space interior space; and means to discharge such collected gases away from the crawl space and/or building interior to the outside atmosphere.
The inventive system vents Radon gas from a building enclosure having a below ground level floor, by sealing the floor with an impervious sheet, by defining a porous path with a fiber mat sandwiched between the floor and impervious sheet, and by venting the mat with a perforated pipe encircling said floor adjacent the foundation walls and positioned on or proximate the mat, with a solid wall pipe connected off of the perforated pipe and extended from the building enclosure to the outside atmosphere.
These and other objects, features or advantages of the invention will be more fully understood and appreciated after considering the following description of the invention, which includes the accompanying drawings, wherein:
The illustrated building 10 might be considered conventional, having a footing (not shown) with an upstanding foundation wall 14 supported thereon, where the footing is in the ground 16 below the freeze line and the foundation wall 14 lies both within and above the ground, and the building side walls 18 are supported on the foundation wall above the ground level 20. Crawl space 22 is defined within the perimeter of the foundation wall 14 between crawl space ground floor 24 and the joists 23 of the building first floor. The typical crawl space floor 24, as noted, might simply be of dirt or dirt covered with some stones, with possibly a thin plastic sheet covering the floor.
This invention provides spreading out a geomembrane mat 30 over the entire crawl space floor 24, extending completely to the foundation walls 14, operable to hold the dirt and stones trapped there under. Further, the mat 30 might have a thickness of approximately 100 mils or more, and can be obtained from Colorado Lining International of Parker, CO. The mat 30 is made from stable flexible material that can be immune to water, where the material may have many separate strands spaced apart leaving small air pockets and channels there between. The mat thereby is porous to the extent that Radon gases escaping from the floor can flow through it both in the direction crosswise to and through it and in the direction parallel to and through it toward and substantially to the foundation walls.
A perforated plastic pipe 32 is positioned on and in close proximity to and in contact with mat 30 immediately adjacent the foundation walls, and follows the walls to completely encircle the crawl space. A tee 34 is fitted in the encircling pipe 32, allowing for connection of a solid wall pipe 36 which is directed up vertically adjacent the building side wall from generally at the crawl space floor to be above the foundation and ground level 20. An elbow 38 is provided thereat for laterally redirecting a solid wall pipe 40 through the building side wall 42 for venting to the outside atmosphere.
A air-tight impervious membrane 44, such as a plastic sheet, overlies substantially all of the mat 30, and is folded approximately 90 degrees near the wall then to extend upwardly from the floor near the inside of the foundation wall, to terminate above the ground surface 20 adjacent the building. The upstanding solid wall pipe 36 is passed through an opening in the sheet, and sealed then tightly to the sheet by tape or by pipe sealant 46. The membrane top is further then sealed to the wall at 48, by a double sided adhesive tape or the like.
The crawl space floor will thus be sealed from the crawl space enclosure spaced above the membrane. Accordingly, even though Radon gas can and will enter the crawl space through the floor 24 from the underside of the membrane, it will be blocked by the membrane and can then only flow via the mat 30 to the perforate pipe 30 and be vented via the solid pipe 36, elbow 38 and pipe 40 to the outside atmosphere proximate the foundation walls. This venting will occur by the pressures of discharging Radon gas, and no venting fan or the like will be needed.
Another aspect of the invention is to enclose the underside of the overhead joists 23 with a sheet material 50 having a reflective foil covering 52 on its upwardly facing side. The upwardly facing foil will tend to reflect the heat of the upper floor room back to the room.
Yet a further aspect of this invention is the installation of a thermal blanket 56 on the outer walls of the crawl space. This blanket 56 would be impervious to gases, and might be used in place of the sealing membrane 44 of plastic if a thermal barrier were desired over the foundation walls in regions of good weather. The blanket and membrane would be taped or otherwise sealed together as at 58 near the lower end of the blanket, the blanket will be sealed to the solid wall pipe 34 as at 46, and the blanket will be sealed at its upper edge 60 by tape or the like to the building foundation wall. This will retain an important aspect of the invention that the crawl space floor and walls will be sealed from the interior enclosure of the crawl space above the floor, so that such sealed region and all collected Radon gases therein can be vented to the atmosphere.
