Patent Publication Number: US-2004050004-A1

Title: Insulated cast concrete wall system and insulation tie

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a system for constructing an insulated cast concrete wall and a tie for securing insulation to a cast concrete wall.  
       DESCRIPTION OF THE PRIOR ART  
       [0002] Cast concrete walls are typically constructed by pouring concrete into a set of forms, curing the concrete and removing the forms. Since energy costs have risen dramatically over the past three decades, it has now become desirable to insulate cast concrete walls. Typically, insulation has been added to the wall after casting and curing of the concrete. However, this technique is very labor intensive and suffers from a lack of effective methods for securing the insulation to the wall. Other techniques have been developed whereby the insulation is placed within the set of concrete forms and the concrete poured around or beside the insulation. In some variations, the insulation may be outfitted with ties which help secure the insulation to the cured concrete. An example of this variation is disclosed in U.S. Pat. No. 6,079,176. While such techniques have increased the effectiveness of securing the insulation to the concrete, they have proven to be labor intensive and have increased the amount of insulation handling. Furthermore, insulation must often be outfitted in advance with ties, or prepared in advance to receive ties, thereby decreasing flexibility of the system and requiring undesirable off-site handling of the insulation. In addition, a system such as that disclosed in U.S. Pat. No. 6,079,176 is difficult to adapt for insulating both sides of a cast concrete wall. Thus, there still remains a need for a simple, flexible and effective method for constructing insulated cast concrete walls.  
       SUMMARY OF THE INVENTION  
       [0003] The present invention provides a tie for securing insulation to a cast concrete wall comprising: a head; a shaft attached to the head and having a longitudinal axis, the shaft comprising a series of barbs positioned at pre-determined longitudinal positions along the longitudinal axis, each successive barb being rotated about the longitudinal axis by a predetermined rotational increment from the immediately preceding barb; and, a tip on the shaft.  
       [0004] There is also provided a process for producing an insulation tie comprising providing a mold having a mold cavity having a shape complementary to the tie; introducing a plastic into the mold; and, forming the tie.  
       [0005] There is further provided a system for constructing an insulated cast concrete wall comprising: a set of concrete forms comprising two opposing partitions set apart a pre-determined distance; a sheet of insulation secured between the partitions adjacent one of the partitions; and, at least one tie consisting essentially of a head, a shaft attached to the head and a pointed or wedge-shaped tip on the shaft, the tie being inserted through the sheet of insulation such that the tip elastically deforms the insulation to permit passage of the shaft through the insulation and a portion of the shaft extends beyond the insulation into a cavity defined within the forms for securing the insulation to the concrete once the concrete has been poured and cured.  
       [0006] There is still further provided a method for constructing an insulated cast concrete wall comprising the steps of: providing a set of concrete forms having opposing partitions set apart a pre-determined distance; providing at least one tie consisting essentially of a head, a shaft attached to the head and a pointed or wedge-shaped tip on the shaft; inserting the at least one tie through a sheet of insulation such that the tip elastically deforms the insulation to permit passage of the shaft through the insulation until a portion of the shaft extends beyond the insulation; securing the sheet of insulation between the partitions adjacent one of the partitions such that the portion of the shaft extending beyond the insulation extends into a cavity defined within the forms; and, pouring concrete into the cavity and curing the concrete.  
       [0007] The tie of the present invention is easy to use and is impaled through the sheet of insulation, obviating the need for pre-forming passages to accommodate the tie. The tie may therefore be inserted through the insulation on-site in any desired pattern, providing flexibility during construction. The system and method of the present invention use conventional concrete forming techniques to quickly erect an insulated cast concrete wall with minimal labour and without re-training of personnel. The ties may be manufactured simply and with low cost using, for example, plastic injection molding techniques. Veneer can be applied to the insulated surface of the wall by fastening the veneer to the ties. Either one or two sides of the wall can be readily insulated using the system and method of the present invention. This permits application of veneer to both sides of the wall if so desired. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0008] In order that the invention may be more clearly understood, preferred embodiments hereof will now be described in detail by way of example, with reference to the accompanying drawings, in which:  
     [0009]FIG. 1 a  is a side view of an insulation tie of the present invention;  
     [0010]FIG. 1 b  is a top view of the insulation tie of the present invention;  
     [0011]FIG. 1 c  is an end view of the insulation tie of the present invention;  
     [0012]FIG. 2 is a sectional view of a system for constructing an insulated cast concrete wall; and,  
     [0013]FIG. 3 is an exploded sectional view of a veneer being attached to an insulated cast concrete wall. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0014] With reference to FIGS. 1 a - 1   c , an insulation tie of the present invention is shown. The insulation tie has a head  1 , a shaft  2 , and a tip  3 .  
     [0015] The head  1  may be of any suitable shape, such as square, rectangular, or preferably round, and has a thickness of preferably about 1 to 5 mm, more preferably about 2 mm. The thickness is chosen to permit a fastener, for example a screw or nail, to be anchored into the head  1  for attachment of a veneer to the insulation tie in a manner that will be more thoroughly described hereinafter. The head  1  may have a diameter of preferably about 5 to 10 times the width of the shaft  2 , more preferably about 7 times the width of the shaft.  
     [0016] The shaft  2  may be of any suitable polygonal cross-section, such as round or rectangular, but is preferably square. Preferably, the width of the shaft  2  is uniform and about ¼ the thickness of the sheet of insulation to be retained. The shaft  2  is preferably attached to the head  1  at substantially the center thereof. The shaft  2  is substantially perpendicular to the head  1  and the longitudinal axis of the shaft defines the longitudinal axis of the insulation tie. The length of the shaft  2  is preferably about 4 to 6 times the thickness of the sheet of insulation to be retained. Gussets  4  are attached to both the shaft  2  and the head  1  to strengthen the tie and help maintain the alignment of the shaft with respect to the head.  
     [0017] The shaft  2  has a tip  3  at the end of the shaft opposite the head  1 . The tip  3  is narrower than the shaft and may be rounded, pointed, or wedge-shaped, preferably pointed or wedge-shaped. When the insulation tie is inserted through a sheet of insulation by impalement of the tie, the tip  3  elastically deforms the insulation to permit passage of the shaft  2  through the sheet. The width of the shaft  2  is chosen so that it may pass through the sheet in co-operation with the tip  3  without forming a hole. The insulation thereby conforms to the outside surface of the shaft  2  when inserted through the sheet. This allows the tie to fit snugly within the sheet and obviates the need for pre-forming holes to permit passage of the shaft  2 , saving labour and allowing the position of the tie to be determined on-site.  
     [0018] The shaft  2  comprises a series of barbs  5  positioned at pre-determined longitudinal positions along the longitudinal axis of the shaft. The increment in longitudinal position between successive barbs  5  in the series need not be uniform. Each barb  5  may be of any suitable shape provided that a portion of each barb extends transversely from the shaft. Preferably, the barbs  5  extend a uniform pre-determined distance from the shaft. Preferably, the barbs  5  have a triangular cross-section and are wedge shaped. Each successive barb  5  in the series is rotated about the shaft  2  a pre-determined rotational increment from the immediately preceding barb. The rotational increment need not be uniform; however, preferably each successive rotational increment is 90 degrees. This arrangement helps ensure that a hole is not formed when the tie is inserted through the sheet of insulation. The series of barbs  5  further comprises counterpart barbs  6  juxtaposed 180 degrees about the longitudinal axis. Each barb  5  in the series therefore has a counterpart barb  6  at the same longitudinal position, but on the opposite side of the shaft  2 .  
     [0019] The longitudinal position of at least one of the barbs  5  in the series, preferably the first barb  7 , is pre-determined according to the thickness of the insulation to be retained. Preferably, the first barb  7  has a face that is substantially perpendicular to the longitudinal axis. The longitudinal position of the first barb  7  is pre-determined so that its face and that of its counterpart  8  rests against the surface of the sheet of insulation when the tie is fully inserted through the sheet. The longitudinal position of the next barb in the series may be pre-determined to accommodate a different thickness of insulation.  
     [0020] The tie may be manufactured of any suitable material that provides sufficient structural strength to allow the tie to be impaled through the sheet of insulation while allowing easy attachment of a fastener to the head  1 . The head  1  and shaft  2  may be made from different materials. The preferred material of manufacture is a plastic and preferably the tie is manufactured as a single piece using a mold.  
     [0021] The preferred process for producing the insulation tie comprises providing a mold having a mold cavity having a shape complementary to the tie. The plastic may then be introduced into the mold by suitable means, for example injected into the mold using a piston or pump. The plastic is then solidified to form the tie using conditions suitable for the plastic chosen; for example, temperature and/or pressure conditions may be selected according to the type of plastic that allow the plastic to be introduced into the mold as a liquid and then changed to solidify the plastic. Suitable plastics include but are not limited to thermoplastics, for example polyolefins, such as polyethylene or polypropylene.  
     [0022] With reference to FIG. 2, a method for constructing an insulated cast concrete wall comprises a set of concrete forms comprising two opposing partitions  9 ,  10  set apart a pre-determined distance. The concrete forms are of the conventional type, typically rectangular and made of wood. The forms are generally transported to the site and setup in a manner that is known to those skilled in the art using a boom truck or similar means to place the forms on top of a pre-prepared concrete footing  11 . A set of concrete forms comprising a series of opposing partitions  9 ,  10  may be assembled with the edges of the partitions  9 ,  10  adjacent to one another. The opposing partitions  9 ,  10  are set apart a distance corresponding to the thickness of the concrete wall to be cast plus the thickness of insulation. The opposing partitions  9 ,  10  may be held together by any suitable connecting means, for example connecting rods  12 , that span the intervening space between the partitions. Each of the connecting rods  12  is attached at one end to one of the partitions  9  and at the other end to the opposing partition  10 . The connecting rods  12  prevent the partitions  9 ,  10  from separating during the subsequent pouring of concrete.  
     [0023] A tie having a head  1 , a shaft  2  attached to the head, and a pointed or wedge-shaped tip  3  on the shaft is inserted through a sheet of insulation  13 . The tip  3  elastically deforms the insulation  13  to permit passage of the shaft  2  through the insulation as previously described. When the tie is inserted through the sheet of insulation, a portion of the shaft  2  extends beyond the insulation. The tie may be inserted on site by any suitable means, such as impact with a hammer or simply by applying pressure to the head  1  of the tie by hand. When the tie is fully inserted, the head  1  is directly adjacent a surface of the sheet of insulation  13 ; alternatively, the tie may be partially inserted and the insertion completed during the subsequent pouring of concrete. A plurality of ties may be inserted in any desired pattern at any desired spacing in each sheet of insulation  13 .  
     [0024] After insertion of at least one tie, the sheet of insulation  13  is placed between the forms and secured adjacent the inside surface of one of the partitions  9 . The sheet  13  is generally rectangular and similar in size to the partition  9  so that the sheet may preferably be secured by wedging it between the connecting rods  12 . Optionally, the sheet  13  may be held in place by a clip (not shown) placed over the connecting rod  12  adjacent the inside surface of the sheet. A single sheet  13  may be inserted against one of the partitions  9  to insulate one surface of the wall or, optionally, a second sheet  14  may be inserted against the opposing partition  10  to insulate both surfaces of the wall, as shown in outline in FIG. 2.  
     [0025] The portion of the shaft  2  extending beyond the insulation  13  extends into a cavity  15  defined within the forms. The cavity  15  is defined by the interior opposing surfaces of the sheet  13  and either the sheet  14  or the partition  10 , depending, respectively, on whether both surfaces or a single surface of the wall is being insulated. The tip  3  of the tie may terminate within the cavity  15  to prevent the tip from protruding through the wall. This is especially desirable when both surfaces of the wall are insulated. Within the cavity  15 , steel re-bar  16  may be added to strengthen the wall. The re-bar  16  is generally comprised of cylindrical corrugated steel strips horizontally oriented within the cavity  15 .  
     [0026] To form the wall, concrete is poured into the cavity  15  and cured. The concrete presses the insulation  13  firmly against the partition  9 , completing the insertion of any partially inserted ties and counter-sinking the head  1  into the insulation until it is flush with the surface of the sheet. The concrete surrounds the re-bar  16  and the portion of the shaft  2  extending into the cavity  15 . Upon curing, the concrete sets around the shaft  2  and the series of barbs  5  anchor the tie within the wall, thereby holding the insulation  13  securely in place. After the concrete has set, the forms may be removed and re-used.  
     [0027] With reference to FIG. 3, after removal of the forms a veneer  17  may be applied to the insulated surface of the wall  18 . A wall that is insulated on one side only is shown in exploded view in FIG. 3, although the same principles apply if both sides are insulated. A veneer  17  may be placed adjacent the insulated surface  18  and fastened to the tie, for example by screwing into the head  1 . The pattern and spacing of the ties are preferably uniform to facilitate attachment of the veneer  17 . The screw  19  is fastened directly to the tie without the need for a pre-formed hole and the tie is not required to spread upon insertion of the screw. For the application of certain types of veneer  17 , it may be desirable to apply strapping, for example strips of wood (not shown), to the surface of the sheet of insulation  18  before application of the veneer  17 . The strapping is preferably fastened to the tie prior to fastening the veneer  17  to the strapping. The strapping is typically oriented horizontally with a single piece of strapping spanning several ties. For interior surfaces, the veneer  17  may include, for example, drywall, paneling, or plywood. For exterior surfaces, the veneer  17  may include, for example, vinyl or aluminum siding, corrugated steel and may further include bricks or stone masonry. The latter may require the use of specialized fasteners in addition to screws  19 .  
     [0028] Other advantages which are obvious and which are inherent to the structure will be evident to one skilled in the art.  
     [0029] It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of the claims.  
     [0030] Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.