Footing forms. They're the first pieces of lumber to show up on job sites -- and they usually look more like a waste pile than building components.
Although good foundation contractors know the benefits of the best wall-forming systems and treat them accordingly, many still use split-out refugees from the scrap pile to set their footings. Sure, these forms perform the lowest job on the totem pole, but the same efficiencies found in wall-forming systems are now available for footings. In fact, several manufacturers offer new, innovative footing systems that make traditional wood site-built forms obsolete. The new systems save time, labor, and materials, and, best of all, increase profits. Here's a look at some of the best new footing forms.
Adjustable, Reusable Aluminum Forming System
Adjust-a-Form, manufactured by the Azar Group, is an extruded aluminum, fully adjustable forming system designed for rapid setup and alignment of footing forms (see photo, page 66). Re-usable forms come in fixed lengths and 5-and 10-foot telescoping sections to easily handle just about any footing dimension. Using two 5-foot telescoping sections, you can cover lengths from 6 1/2 to 9 1/2 feet. You can span 10 to 18 feet with two 10-foot telescoping sections. Both types of sections fasten with aluminum alloy pins that drop into pre-drilled holes. The hinge-type connections allow inside angles of 45 to about 270 degrees. You can also form square corners with special diagonal bars that run through pre-drilled corner alignment holes.
Setting form elevations is easy. Simply slide individual form sections up or down along the system's steel anchor stakes and lock them in place by tightening thumbscrews. Both telescoping and fixed-length sections include self-adjusting stakes for easy elevation control.
Fixed-length and telescoping sections come in 3 1/2-, 6-, 8-, and 10-inch-heights. You can also order 10-foot, fixed-length forms in heights of 11 to 24 inches, and 10-foot flexible sections in 3 1/2-, 4-, 5-, 6-, and 7-inch heights. Flexible sections are designed primarily for forming sidewalks, driveways and patios, but can be bent to form curved footings with a radius as small as 3 feet.
The Adjust-a-Form system requires no cutting, nailing, or wood stakes. Thus, one worker can build footing formwork for a typical residence in a few hours. It usually takes a crew all day to build traditional wood formwork. Given the time savings, says Azar Group vice president Mark Hopkinson, contractors can quickly recover the system's initial cost after using it two or three times.
Forming Footings With Fabric
Fastfoot Industries' Fastfoot system uses a coated, high-density polyethylene fabric called Fastfabric, 2x4 supporting strips, and specially built steel yokes to form footings. According to Fastfoot operations manager Rick Fern, it's a simple three-step process. First, place pairs of 2x4s into the adjustable-height yokes. Then staple Fastfabric to the 2x4s. Forms can then be filled with concrete.
Yoke legs telescope, which makes it easy to adjust forms to the proper elevation. Yokes are placed about 10 feet apart and require no stakes. Fern says workers can typically install up to 100 linear feet of Fastfoot forms per hour, even on hard or rocky ground.
Fabric forms conform to uneven and sloping sites, are extremely lightweight, and can handle up to 18-inch-thick footings. Fastfabric comes in 120-foot lengths and in widths of 62 and 74 inches. It's marked to help workers properly align the fabric before stapling. You save time and labor by leaving the fabric in place and using the 2x4s to align the foundation wall forms says Fern. Because the fabric protects the 2x4s during concrete placement, the lumber comes off the footing clean and ready for the next job.
In addition to strip footing forms, Fastfoot Industries manufactures pre-sewn fabric bags for pad footings called Fastbags. Bag sizes start at 18 inches square and increase in 6-inch increments up to 48 inches square. Access zippers let you place rebar inside bags.
You can fill Fastfoot forms with a concrete pump or from a ready-mix truck's chute. Regardless of the placement method, Fern recommends using a water reducer or plasticizer to aid in concrete placement. (Water reducers increase the fluidity and workability of fresh concrete.) Kicking the sides of the fabric form or bag at regular intervals during the pour helps ensure that the form is completely filled.
Slotted PVC Drain Formwork
Form-A-Drain, manufactured by CertainTeed, is a stay-in-place system that forms footings, drains the foundation, and can evacuate radon gas when modified according to EPA specifications. It consists of hollow, rectangular PVC pipes that come in 12-foot lengths and three sizes: 2 1/4 x 4, 2 1/4 x 6, and 2 1/4 x 8 inches. The two largest sizes contain horizontal stiffening webs that divide the tubes into two drainage channels. Form-A-Drain sections are lightweight and easy to install; a 12-foot length of the 4-inch pipe weighs less than 6 pounds.
One side of the form is slotted, which allows ground water to enter into a drain channel and exit through outlet sections. The concrete-facing side is solid to prevent concrete or mortar from entering a drainage channel. Form-A-Drain provides drainage on both sides of the footing; CertainTeed recommends locating the system just below and parallel to the foundation wall.
Spacer straps and rebar stakes hold forms in place during assembly and concrete placement. Traditional grade stakes allow you to set them at the proper elevation. Since the PVC sections are easily cut with hand or power saws, you don't need special tools for assembling the system. All field-connections are made dry, allowing workers to connect pieces without solvent cement or mechanical fasteners. The manufacturer offers a full line of Form-A-Drain accessories, including couplings, corners, drain outlets, tee connectors, and other pieces.
Engineered, Re-usable Laminated Veneer Lumber (LVL) Forms
PacForm is a LVL foundation form product manufactured by Pacific Wood Laminates. Form planks consist of solid wood veneers laid out in a parallel grain with two solid veneer crossbands. They're precision-engineered to minimize defects, warping, shrinkage, and waste. Form pieces are uniformly flat and true, and are sanded on both sides to ensure smooth concrete finishes. Ken Caylor of Pacific Wood Laminates says PacForm is stiffer and less variable than lumber or oriented strand board (OSB) products. Caylor also says PacForm outperforms traditional wood products in price and durability, thereby reducing the overall formwork cost.
PacForm ranges in length from 8 to 24 feet. It's available in heights of 2 1/2 to 48 inches and in thicknesses of 5/8 to 1 13/16 inches. PacForm can be sawn, drilled, and nailed just like dimensional lumber, so no special tools are required for assembly. Its wide range of available sizes give it an advantage over dimensional wood forms, as does its superior durability. A fairly new formwork product, Pacform's an environmentally sustainable material manufactured from second-growth timber.
Stay-in-Place Expanded-Metal Panels
Alabama Metal Industries manufactures an expanded metal product specifically for wall-forming applications. Stay-Form is made of galvanized sheet steel that's lanced and expanded to form a mesh. Solid 3/4-inch deep stiffening ribs run along the length of the 27x97-inch panels. A standard 26-gauge panel weighs approximately 12 pounds; a heavier panel made of 27-gauge stock weighs 14 pounds.
You don't need special tools to cut and shape the expanded-metal panels. Workers typically use circular saws equipped with abrasive metal-cutting blades or tin snips for smaller cuts. Panels are flexible enough to be curved by hand and can readily be shaped to form unusual footing configurations.
Forming footings with expanded-metal panels is similar to building traditional wood job-built formwork, but Stay-Form's much stronger. Orient panels with the stiffening ribs aligned perpendicular to the supporting stakes and facing inward so ribs will be embedded in the fresh concrete. You can use either wood or rebar stakes to support the forms and attach panels to stakes using either nails or tie wire.
Expanded-metal forms are designed to be used with 3- to 4-inch slump concrete, but Stay-Form's manufacturer says you can use up to a 6-inch slump with proper precautions. If the slump is excessive, large amounts of grout may flow through the mesh openings. However, using Stay-Form also reduces chances of form misalignment and blowouts because mesh openings sluice off mix water, which significantly reduces lateral form pressures.
Expanded-metal forms are relatively new to the residential construction industry and like the other systems described above, they provide an innovative, labor-saving way of building formwork for footings.
Sources of Supply
Azar Group of Companies
Windsor, ON, Canada
Fastfoot Strip System
Surrey, BC, Canada
Valley Forge, PA
Pacific Wood Laminates
Alabama Metal Industries
Kim Basham is a contributing editor for Concrete Construction and engineering director for the World of Concrete tradeshow.