Horizontal Re-bar

Horizontal steel reinforcing bar (re-bar) must be installed as the wall assembly is erected. The re-bar is placed in the tandem re-bar saddles provided on the center of each wall-tie every 12-inches on center, although, it may only be necessary to install horizontal re-bar every second or third course. These dual re-bar saddles will accept both ½ and 5/8-inch re-bar. All overlapping splices, including those at corners, should overlap 36 bar diameters and should be tied with wire. It will also be important to plan the placement of re-bar to correspond with other elements of the wall assembly. It is a good idea to check the details of window and door openings, lintels, and other wall features to determine the required steel reinforcing. It is much easier to place re-bar as the wall assembly is being erected than it is after. See: Vertical Re-bar.

Engineering and architectural specifications and drawings will determine the size, grade, and the position of the steel reinforcing bars. The placement and design of steel reinforcing shall be in accordance with local standards and regulations, and in conformance with ACI 318-95 Building Code Regulations for Structural Concrete.(back to top)

Vertical Re-bar

Vertical steel reinforcing (re-bar) dowels should be placed in the footer at regular intervals. These dowels should correspond with the design of the re-bar required in the wall. This will provide solid attachment to the footing. See: Footings.

The vertical re-bar is most easily put in place full length after the wall assembly is erected and prior to concrete placement. Several methods can be used to hold vertical re-bar in place. First, attach an open wire loop at the top of the dowels large enough so that the vertical re-bar can be passed through and held in place at the bottom once the wall assembly in completed. Second, a two-inch length of PVC pipe (a ring) can be slipped over the dowel and serve the same purpose as the wire loop. Both the wire loop and the PVC ring need to be sized correctly so the vertical re-bar is held reasonably tight to the vertical dowel protruding from the footer. Third, various market-ready re-bar positioners are available, and fourth, the vertical re-bar can be bushed into the correct location as the first lift of concrete as it is being pumped in place. All of these methods allow for full-length re-bar to be used. A fifth way is that the vertical re-bar can be installed in two or more pieces with joints that overlap 36 times the bar diameter and tied with wire. With this method the vertical bar can be tied to the horizontal re-bar with wire, and the forms will be installed by slipping them over the vertical re-bar. See: Vertical Re-bar

It may be necessary for workers to hold and/or move the vertical re-bar into place during concrete placement. If this is done, care should be taken to insure that the re-bar is maneuvered into proper position as the concrete is being placed. This will need to be done during all lifts of the concrete pour. See: Concrete Placement.

If vertical re-bar is not to extend and connect to a wall of an additional story above, it should be cut to a length 1 or 2-inches shorter than the wall height. If the vertical re-bar is to extend and connect to a wall of an additional story above, it should be cut to a length so that it will overlap 36 bar diameters with the vertical re-bar that will be installed above. Or, short pieces of re-bar can be placed in the fresh concrete at the top of the wall, that are long enough to protrude into and connect to the wall that will be built above.

The vertical re-bar can be tied in place or it can be held in place when concrete is being pumped into the forms. It is important to know that for above grade walls the re-bar should be held in the center of the wall cavity. For below grade basement foundations where there is lateral load (pressure) against the wall the vertical re-bar is best held off center on the tension side (basement side) of the wall with a minimum of 1-inch concrete cover. It is important to plan the placement of re-bar to correspond with other elements of the wall assembly and to check the details of window and door openings, lintels, and other wall features to determine the required steel reinforcing. See: Horizontal Re-bar.

Engineering and architectural specifications and drawings will determine the size, grade, and the position of the steel reinforcing bars. The placement and design of steel reinforcing shall be in accordance with local standards and regulations, and in conformance with ACI 318-95 Building Code Regulations for Structural Concrete.(back to top)

Intersecting Walls (T-walls)

To connect intersecting walls it will be necessary for the concrete and steel re-bar of both walls to be linked together. To accommodate for the re-bar and the flow of concrete, sections of the foam panel on one side of the adjoining wall will need to be removed. To form a non-fire rated T-wall, remove sections of foam located above and below the wall-ties and between the flanges of the studs. It is important to avoid cutting the stud wall-tie brackets, whenever possible.

When the cutting wall-ties is unavoidable, such as when forming a solid monolithic fire rated T-wall, or when the entire side of the adjoining wall needs to be removed, it will be necessary to reinforce the intersecting area in order to withstand the pressures created during concrete placement. Reinforcing is usually accomplished by supporting the area with pieces of wood attached with course thread screws, and replacing the cut plastic wall-tie brackets with wall ties made of wire to hold both sides of the wall assembly together. See: External Bracing.(back to top)

External Bracing

Bracing is not required under normal circumstances for the pre-molded corner forms. This is especially true if the horizontal joints are glued and the correct concrete slump is being used during concrete placement. Many installation contractors choose to use vertical plumb boards at the corners to insure that the installation of the wall assembly is plumb and the building is square.

External corner bracing is required when corners are made from straight forms miter cut to form a corner. In this case the corners will need to be reinforced and braced to accommodate the pressures of concrete during concrete placement. To reinforce mitered corners, the cut joints should be glued with foam-compatible contact adhesive or minimum expanding foam adhesive and taped. The corner will need to have temporary wood or metal supports applied vertically and tied together through the wall with wall ties made by using tie wire and braced with kickers from two directions.

The construction of intersecting walls (T-walls), gable end walls, and other complicated or difficult areas where the integrity of the forms has been compromised, will also require external bracing. Care should always be taken when placing concrete in these areas, lowering the risk of form separation, wall deformity, budges, and blowouts. See: Intersecting Walls, Cut Forms and Splices, Bulkheads, Gluing Forms, and Window and Door Openings. (back to top)

Window and Door Openings

Window and door frames (bucks) are installed by placing a vinyl or wood frame that has the same inside dimensions as the required rough opening (RO) size as supplied by the window and door manufacturer.

Use pressure treated 2 x 12 dimensional lumber to construct the top and sides of the frame, but use two 2 x 4's on the bottom leaving a space between them for concrete to be placed under window or door openings. It may be advisable for this space to be filled with a third piece of 2 x 4, to be used for attaching finished materials, once the concrete has filled the cavity under the frame. The frame is left in place after the concrete is cured providing a fastening surface for the installation of the windows, doors, and finish trim.

Attach temporary 1 x 4 wood flanges on all edges of the wood frame to position and hold the form in alignment with the wall. Additionally, temporary vertical, horizontal, diagonal and/or cross bracing will need to be installed to reinforce the frame to prevent the weight of the concrete from pushing in, down, and up against the frame causing it to move and/or change shape. It should be noted that ready-mixed concrete weighs approximately 4000 lbs. per cubic yard and bracing should be built accordingly.

Metal fasteners (nails, screws, or bolts) should be installed into the frame (top, sides, and bottom) prior to the placement of concrete so they protrude into the wall cavity securely anchoring the wood frame in-place once the concrete is cured.

Commercially available preformed plastic and vinyl frames are installed similarly and provide the same utility. Follow the instructions for installing vinyl frames as provided by the manufacturer. Manufacturers of these products are: ICF Building Products, LTD. www.icfbp.com, and Vinyl Technologies, Inc.: www.vbuck.com.

Window and door openings require that concrete steel reinforced lintels be built to span the openings carrying the load of floors, roof, and point loads from beams, girders, and trusses. Care should be taken when sizing, locating, and installing re-bar during the construction of lintels. Additionally, placement of concrete must be consolidated to ensure that the steel reinforcing bar (re-bar) are fully embedded and that no voids occur in the concrete. This is especially important in areas around window and door openings, and in lintels where the positioning of re-bar may inhibit concrete flow. For this reason, it is always best not to place any concrete into lintels until the elevation of the concrete lift being placed can fill the wall and lintel cavities at the same time, creating a continuous monolithic pour.

Engineering and architectural specifications and drawings will determine the size, grade, and the position of the steel reinforcing bars. The placement and design of steel reinforcing shall be in accordance with local standards and regulations, and in conformance with ACI 318. (back to top)

Bulkheads

Bulkheads are required to stop concrete at open-ended walls and need external support to keep them in place. A bulkhead is made by using a 2 x 12 with temporary 1 x 4 flanges attached vertically to each side and placed over the end of the wall. Adequate bracing or strapping must be installed to keep the pressure of the concrete from pushing the bulkhead out during concrete placement. If the bulkhead is to be left in place, use a treated 2 x 12. Concrete nails, screws, or bolts should also be installed to extend into the wall cavity before placing concrete. Bulkheads and other custom areas may also need to be secured plumb, in two directions, using braces with turnbuckles.(back to top)

45-Degree and Other Custom Corners

To miter cut Standard ICF straight forms to make 45-degree and various other acute and obtuse corners is not difficult. Layout two (2) straight forms with tongue side up and facing in the same direction. Make measurements on each form starting from the groove end but on opposite sides (reversing the cut) creating an axis that divides each form into two asymmetrical pieces. Mark the vertical lines on the sides of each form with a square and make vertical miter cuts with a carpenter's handsaw down the center of the lines.

Make the miter cut by cutting down through both panels at the same time. Proceeding slowly and following the lines on both sides of the form will insure an accurate miter. When both forms are cut, exchange the pieces to create a form with two (2) opposing corners with the same angle. Each corner form should have a tongue and a groove end and a short and a long leg. Fit pieces together and glue with foam-compatible contact cement and/or tape. See: Installation Guide.

All special cut corners will need to have temporary external wood or metal bracing/supports applied vertically on both sides of the wall assembly and tied together through the wall with wall ties made of wire. Miter cut corners and other custom areas may also need to be secured plumb, in two directions, using braces with turnbuckles.(back to top)

Rim Joists and Ledgers

The framing of floors and ceilings are often attached to rim joists or ledgers. To attach rim joists and ledgers (joist/ledgers) to the side of an ICF wall, a structural side attachment is required using a series of anchor bolts or a ledger connector system. Only when concrete has had time to cure properly should structural framing be attached to the joist/ledgers that have been installed with anchor bolts or ledger connectors.

To use the anchor bolt method, multiple sections of foam panel will need to be removed from the side of the wall assembly between the stud wall-tie brackets and within the area to be covered by the joist/ledger. The joist/ledger is then secured in place over the series of openings that have been cut in the side of the wall assembly by attaching it to the wall surface with course thread screws to the stud flanges. Holes are then drilled through the joist/ledger to receive the required size and spacing of anchor bolts as designated by architectural and/or engineering design. When concrete is pumped into the wall cavity it will flow into the open spaces in the foam panels and surround the ends of the anchor bolts embedding them securely in concrete.

The ledger connector method is simply done by making a series of single vertical cuts through the foam panels in the location where the joist/ledger is to be located in the wall assembly. The ledger connectors are then pushed into the cuts and friction fit in place. When the concrete is pumped into the wall cavity it securely embeds the ends of the connectors. An ICF Ledger Connector System manufactured by Simpson Strong-Tie is available through ICF Building Products, LTD.: www.icfbp.com.(back to top)

Beam and Girder Pockets

To accommodate for the end of a beam, girder, or truss that will carry the total loads associated with the interior structure of the building, a beam packet will need to be formed in the ICF wall assembly before concrete is put in place. To do this, a piece of the interior foam panel and/or parts of stud wall-tie brackets will need to be removed.

Once removed, the open area will need to be blocked-out with pieces of wood or a slab of foam inserted into the wall cavity and secured in place to create a void. The block-out pieces should be made so they can be easily removed once the concrete has cured. The bottom of the block-out should be located at the elevation designated as the bottom of the beam/girder/truss.

It is important to make these pieces slightly larger than the beam/girder/truss so the end of these structural members can be inserted easily and the correct elevation can be adjusted with non-shrink grout, or wood or metal shims, when the beam/girder/truss is put in place. It is also important that there is enough concrete support under the beam pocket to carry the anticipated total load. To accomplish this, a larger amount of foam panel may need to be removed to allow for a concrete corbel to be formed. Exterior bracing may need to be provided when forming a beam pocked so as to withstand the pressures of concrete. (back to top)

Brick Ledge

Forming a brick ledge to use for installing veneer brick and stone can be accomplished by using a simple wood or metal form attached to the side of the wall assembly at any desired elevation. Once the elevation is established, sections of foam are removed from between the stud flanges and from between the top and bottom of the brick ledge form allowing concrete to flow into the brick ledge form. Re-bar is also required in the construction the brick ledge.

Engineering and architectural specifications and drawings will determine the size, grade, and the position of the steel reinforcing bars. The placement and design of steel reinforcing shall be in accordance with local standards and regulations, and in conformance with ACI 318-95 Building Code Regulations for Structural Concrete.

Utility, Mechanical, and Service Penetrations

Openings will need to be provided in walls for all utilities, mechanical systems, and service entrances. Such items include, but are not limited to, electrical, telephone and television cables, water supply pipes, gas lines, air supply and exhaust pipes, ducts, vents, sewer drain pipes, beam pockets, and access doors or panels. Penetrations are made so that the installation of these essential components can be installed after the concrete is in place, with less effort and cost. In addition, penetrations for the installation of a Heat Recovery Ventilator (HRV), also known as an Air-to-Air Heat Exchanger, should be considered before concrete placement as well. See: Important Notice below.

A penetration is easily accomplished by sawing a hole in the desired location through both panels of the form to allow for the installation of a sleeve or chase (pipe or frame) through the wall. The sleeve or chase should be slightly larger than the actual utility or service penetration being installed. Large access openings are made in the same way as window openings.

Foam adhesive can be use to secure sleeves and chases in place, and to seal around the penetration once it is installed. It is less costly to plan ahead and imagine the need and possibility of future or additional openings for penetrations at this time. Extra or unused holes can be easily filled and covered over for future use when needed.

Important notice: Because new buildings are built far more air-tight than those built in the past, the need for providing clean, fresh, unpolluted, and balanced indoor air in buildings has become very important. The need for improved indoor air quality in ICF buildings is no different. Most all new buildings need mechanical ventilation to keep the air inside fresh and prevent the build -up of indoor air pollutants such as excess moisture, carbon dioxide, formaldehyde and various volatile organic compounds found in building materials, paints, furnishings, cleaning products and smoke. For these reasons it is important to consider the installation of a Heat or Energy Recovery Ventilator (HRV or ERV), also known as an Air-to-Air Heat Exchanger as part of any Heating, Ventilating and Air Conditioning (HVAC) system in the building at this time. Consult with your HVAC contractor or consultant concerning the need for these mechanical devices and the size and location of any wall penetrations that it will be required for their installation.

Ventilation Products available through ICF Building Products, LTD. www.icfbp.com
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