Patent Application
20080163577
One foundation technique frequently used in home building is to construct a stem wall. A stem wall anchors a home firmly in the ground, working like roots to hold a house down and tie it into the ground below. Further, the stem wall, being positioned around the perimeter of the house, provides support for the exterior load bearing walls of the home. It should be noted the stem wall can also provide support for interior load bearing walls or any non-load bearing walls.
A stem wall is constructed in place at the home site. Typically, the stem wall is constructed of concrete masonry or cinder block reinforced with steel and concrete. The home site is excavated and compacted using new fill. Then, a footing trench is excavated around the footprint of the house. The footing size is typically 12 to 16 inches wide by 8 to 12 inches deep. The concrete footing is poured, typically with reinforcing steel extending up from the footing. Sometimes, when the concrete of the footing sets up, the first course of block is set in place.
A stem wall is typically three masonry courses high. Every set number of inches, which varies depending on code and the height of the wall, the blocks are fitted with steel rebar for reinforcement. Further, concrete is poured into the block cells. Once the three-course wall is in place, dirt is backfilled against the exterior of the stem wall.
The house can be placed on and attached to the stem wall, leaving a crawl space beneath the house. Alternatively, the interior of the stem wall can also be backfilled and compacted to serve as the base for a concrete slab.
If a slab is to be formed, typically the cells for the stem walls are filled with concrete at the same time the slab is poured, as one continuous pour. When the cells are filled for the wall, the slab is poured as the top layer or seal for the walls. The reinforcing steel or rebar extends above the wall and slab for the tie-in to the walls. Ties and anchor bolts are wet set in the concrete so that they are completely tied into the structure.
Stem walls formed in such a way provide a very stable foundation which protects from damage even in rising waters, seismic events, and high winds. However, it is desirable to improve the efficiency of forming stem walls.
In one embodiment, a stem wall is manufactured and then transported to the house site for placement. Preferably, the stem wall is manufactured within an enclosed facility; however, the stem wall can be manufactured outdoors or in any other suitable location. Further, the stem wall is preferably manufactured at a location which does not require transporting the stem wall via public roadways to the house site; however, the stem wall can be manufactured at a location for which transporting the stem wall to the house site via public roadways would be necessary or desirable.
In one embodiment, the stem wall is manufactured by pouring concrete into a mold. Tension cables (e.g., high strength steel tension cables or any other suitable type of tension cable) are positioned within the mold and are stressed after the concrete cures to provide increased tensile strength. It should be noted that other reinforcement devices (e.g., steel rebar or any other suitable reinforcing device) can also be positioned within the mold. In one embodiment, the stem wall is formed with one or more horizontal openings. Beams or pegs can be inserted through the horizontal openings to facilitate transportation of the stem wall to the house site.
In another embodiment, exterior face attachment points (e.g., exterior brackets, protrusions or any other suitable graspable structure) are attached to one or more exterior surfaces of the stem wall. The exterior face attachment points can be attached after concrete is poured into the mold or can be positioned with the mold such that the exterior face attachment points are formed as a continuous part of the stem wall.
In one embodiment, before the stem wall is transported to the house site, a house is built or placed on top of the stem wall. Preferably, the house is secured to the stem wall; however, the house is not required to be secured to the stem wall.
In one embodiment, the ground at the house site is excavated and compacted. The stem wall is then transported to and placed at the house site. Optionally, a trench or caisson can be dug and a footer or post formed on which the stem wall can be positioned; however, such an in-place footer or post is not required. Alternatively, the compacted ground can be excavated in parts to enable a bottom portion of the stem wall to be positioned within the excavated parts. In another embodiment, the stem wall is merely positioned on top of the ground. Once in place, the stem wall is preferably at least partly buried by backfilling.
Additional features and advantages are described herein, and will be apparent from, the following Detailed Description and the figures.
In one embodiment, a stem wall is manufactured and then transported in any suitable manner to the house site for placement. Preferably, the stem wall is manufactured within an enclosed facility; however, the stem wall can be manufactured outdoors or in any other suitable location. Further, the stem wall is preferably manufactured at a location which does not require transporting the stem wall via public roadways to the house site; however, the stem wall can be manufactured at a location for which transporting the stem wall to the house site via public roadways would be necessary or desirable. Further still, the stem wall can have any suitable dimensions, including, but not limited to: those which would provide a foundation for a house or other structure that is too large to transport over public roads due to legal, physical or any other limitation; those having length and width dimensions such that the smaller of the length and width dimensions is greater than 16 feet; and those which would support a multiple story structure. It should be noted that a stem wall can also be transported to a site (i.e., a structure site) for any suitable type of structure (e.g., a townhouse row, a commercial facility, an apartment complex, an agricultural building, etc.) and that house or home sites are a subset of structure sites.
In one embodiment, the stem wall is manufactured by pouring concrete into a mold. Preferably, the mold includes one or more mold sections. Mold sections can be of any suitable configuration (e.g., right angle corners, T-intersections, cross intersections, straight sections, curved sections, any suitable corner joint joining any suitable number of wall portions arranged at any suitable angle) and can have any suitable length or dimensions; however, a segmented mold is not required, and a mold can be built in a non-modular or even non reusable manner. To build a mold, suitable segments are selected and arranged together. The mold can have any suitable shape, and preferably at least includes the perimeter of the eventual house which will rest upon the stem wall; however, the mold is not required to include the perimeter of the eventual house and can include internal walls running between exterior walls or other interior walls.
Typically, the concrete is a mixture of cement and a sand and/or gravel aggregate; however, the concrete can be any suitable mixture including, but not limited to, those having a lighter weight aggregate such as pumice, scoria, volcanic cinders, tuff, diatomite, heated/processed clay, heated/processed shale, heated/processed slate, heated/processed diatomaceous shale, heated/processed perlite, heated/processed obsidian, heated/processed vermiculite, or industrial cinders, Styrofoam, plastic or ceramic beads or nuggets, blast-furnace slag that has been specially cooled and/or mixtures including foaming agents such as aluminum powder (which produces gas while the concrete is still plastic) or other pocket forming materials. Alternatively the stem wall can be manufactured from cement or by layering cinder blocks with rebar inserts and concrete or cement filling as is typical of stem walls formed at the house site or in any other suitable manner using any other suitable substance.
Preferably, tension cables are positioned within the mold and are stressed after the concrete cures to provide increased tensile strength; however tension cables are not required and the stem wall can be unreinforced or reinforced with any suitable component such as rebar or a wire mesh or any combination of suitable reinforcement components.
In one embodiment, the stem wall is formed with one or more horizontal openings. Beams or pegs can be inserted through the horizontal openings to facilitate transportation of the stem wall to the house site. Preferably, the openings are configured such that a beam can extend through two exterior walls of the stem wall; however, such a configuration is not required. In an alternative embodiment, instead of or in addition to the horizontal openings, one or more protruding members are formed extending from one or more exterior walls of the stem wall. The protruding member can be part of the mold and poured similar to the rest of the stem wall. Alternatively, a beam (e.g., a steel I beam) is positioned with the mold such that when the stem wall is poured, a portion of the beam extends beyond the exterior surface of the stem wall.
In another alternative embodiment, exterior face attachment points (e.g., exterior brackets, protrusions or any other suitable graspable structure) are attached to one or more exterior surfaces of the stem wall. The exterior face attachment points can be attached after concrete is poured into the mold or can be positioned with the mold such that the exterior face attachment points are formed as a continuous part of the stem wall.
In one embodiment, after the stem wall is formed, it is transported to and positioned at the house site. Preferably, one or more ground transportation devices are coupled to the stem wall by gripping the beams or other objects (e.g., cables, brackets, etc.) inserted through the horizontal holes; however, the devices can be coupled to the stem wall in any other suitable manner, including but not limited to by inserting pegs of the devices into the horizontal holes or by gripping one or protruding members or exterior attachment points described above. It should be noted that the stem wall is not required to be transported by a ground vehicle and that the stem wall can be transported by an air vehicle (e.g., a helicopter), a water vehicle (e.g., a barge) or any other suitable vehicle (e.g., a crane, an amphibious craft, etc.).
Once positioned at the house site, the interior portion of the stem wall can be filled and compacted; however, the filling and compacting is not required and the interior portion can be left as a crawl space. A concrete or any other suitable slab can be poured integral with the stem wall; however, such a slab is not required. Then, a house or other structure can be built or placed upon the stem wall. The stem wall can be attached to the house, slab or other structure in any suitable manner, including, but not limited to, pouring onto protrusions (e.g., rebar or wire mesh) from the stem wall, caulk, tar, or other adhesives or bonding agents, anchors bored or placed during formation into the stem wall, bolts, epoxies or any other suitable joining substances or structures.
In another embodiment, before the stem wall is transported to the house site, a house is built or placed on top of the stem wall. Preferably, the house is secured to the stem wall in any suitable manner, including those described above for a site-built or attached house; however, the house is not required to be secured to the stem wall. In one embodiment, the stem wall is placed or formed on skates which are operable to transport the stem wall within a home or other structure manufacturing facility or site; however, the stem wall can be transported within the facility or site in any suitable manner (e.g., rails, cranes, vehicles, air cushion, dollies, reduced friction surfaces, etc.) or remain stationary until being transported to the home site. Alternatively, a stem wall can be manufactured at one facility or site and transported to one or more other facilities or sites at which a house is at least partly built of placed upon the stem wall before the stem wall is transported to and placed at the house site.
Preferably, the stem wall is moved on the skates from station to station, and at each station one or more portions of the house or structure is built on or added to the stem wall/house structure. However, the stem wall is not required to be moved from station to station. The stem wall can remain substantially in one position while house or other structure is placed or built upon the stem wall. For example, a full-sized house (e.g., a non-roadable house, a mini-mansion, houses larger than mobile homes, etc.) can be built or assembled within the facility or brought to the facility and attached to the stem wall. Alternatively, a full-sized house can be built in any suitable manner (e.g., stick building, panelized building, modular building) onto the stem wall. Further it should be noted that alternatively, a smaller dwelling such as a mobile home can be placed or built upon the stem wall. It should also be noted that structures other than houses (including but not limited to townhouse rows, apartment buildings, commercial structures, agricultural buildings or any other suitable structure) can be placed or build upon the stem wall.
In one embodiment, after the stem wall and house are coupled, the stem wall and house are transported to the house site in any suitable manner, including, but not limited to, those described above for transporting the stem wall. Alternatively or additionally, transporting the stem wall and house can include coupling a moving apparatus (e.g., one or more vehicles, a crane, etc.) to a structure of the house, a protrusion from the house, an opening into the house, any of the mechanisms described in co-pending U.S. patent application Ser. Nos. 11/431,196 and 11/559,229, the entire contents of both of which are incorporated herein, or any other suitable mechanism for grasping the house as well as or instead of the stem wall.
In one embodiment, the ground at the house site is excavated and compacted. The stem wall is then transported to and placed at the house site. Optionally, a trench, column, caisson or pier can be dug and a footer or post formed on which the stem wall can be positioned; however, a such an in-place footer or post is not required. If such an in-place footer or column is formed, the stem wall is preferably placed thereon before the footer or column has set. Further, one or more protrusions (e.g., rebar or wire mesh) from the stem wall are preferably inserted into the footer, column or caisson when the stem wall is placed. However, such protrusions are not required and the column or footer can be allowed to set before the stem wall is placed upon it.
Alternatively, the compacted ground can be excavated in parts to enable a bottom portion of the stem wall to be positioned within the excavated parts. In another embodiment, the stem wall is merely positioned on top of the ground. Once in place, the stem wall is preferably at least partly buried by backfilling; however, the stem wall is not required to be even partly buried. Further, the stem wall is preferably buried to a level sufficiently high to cover one or more openings and/or protrusions used in transporting the stem wall to the house site; however, it is not required to bury such openings and/or protrusions, if any.
The floor/sub-floor 606 is separated from the interior wall 604 by a spacer 608. The spacer 608 is preferably more compressible than the material used to form the stem wall 600 and can include wood, plastic or any other suitable material; however, spacer 608 is not required to be more compressible than the material used to form the stem wall 600. Further, the spacer 608 can include a material that joins the floor/sub-floor 606 and the interior wall 604, such as tar, caulk, epoxy or any other suitable bonding or adhering material.
The floor/sub-floor 606 is also separated from the exterior wall 602 by a spacer 610. The spacer 610 is preferably more compressible than the material used to form the stem wall 600 and can include wood, plastic or any other suitable material; however, spacer 610 is not required to be more compressible than the material used to form the stem wall 600. Further, the spacer 610 can include a material that joins the floor/sub-floor 606 and the exterior wall 602, such as tar, caulk, epoxy or any other suitable bonding or adhering material. Above the exterior walls 602 are the exterior house walls 612. Further, at least one of the exterior walls 602 includes a female structure tube 614, into which a beam or peg can be inserted for transporting the stem wall 600 as described above. It should be noted that instead of or in addition to the tube 614, the stem wall 600 can include one or more protrusions or exterior surface attachment points.
The exterior wall 712 has an upper portion 714 which includes a lower top surface 716 and an upper top surface 718. Preferably, the stem portion 720 extending above the lower top surface 716 to the upper top surface 718 is positioned such that the floor/sub-floor rests on both the upper top surface 718 and lower top surface 716. Further, the floor/sub-floor can contact and/or be attached to the interior side of stem portion 720 in any suitable manner, including but not limited to bolts, anchors, caulk, adhesives, or any other suitable joining mechanism or substance. The exterior side of stem portion 720 is exposed to the ground and/or air outside the stem wall 700.
It should be noted that a stem wall can have any suitable configuration.
It should be appreciated that in various embodiments, the interior of the stem wall could be filled (e.g., with concrete or cement), forming a mobile slab. The interior can be filled as part of forming the stem wall (making the stem wall and slab one continuous, possibly indistinguishable, piece), or subsequent to forming the stem wall. Similar to embodiments described above, the mobile slab can be transported to the house site with or without a house placed or built on the slab. Further, in various embodiments, the slab has one or more pockets or holes which reduce the weight of the slab.
It should also be appreciated that any dimensions described above or provided in the drawings are for exemplary purposes and that the respective objects can have any suitable size, shape and configuration.
It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.
This application is related to U.S. application Ser. No. 11/431,196, entitled “BUILDING TRANSPORT DEVICE”, filed May 9, 2006, and U.S. application Ser. No. 11/559,229, entitled “TRANSPORT DEVICE CAPABLE OF ADJUSTMENT TO MAINTAIN LOAD PLANARITY”, filed Nov. 13, 2006 the entire contents of both of which are herein incorporated by reference.
