Sonotubes play a critical role in the construction of pole barns and concrete foundations, serving as durable, reusable cylindrical forms that ensure structural integrity and alignment during the concrete pouring process. Proper installation of these tubes is essential to achieving a level, stable base for posts, columns, and other load-bearing components. This article provides a detailed, step-by-step overview of Sonotube installation practices based on verified construction methods and technical guidance from authoritative sources. The focus is on practical application, alignment, bracing, and integration with structural components such as brackets, splashboards, and rebar.
Overview of Sonotube Installation in Pole Barns
Sonotubes are commonly used in pole barn construction to house concrete piers, which serve as the foundational support for vertical columns and wall assemblies. These tubes are typically made of heavy-duty cardboard and are designed to remain in place after the concrete has cured, providing long-term durability and resistance to moisture and decay.
In pole barn construction, Sonotubes are installed after the footings are poured and partially cured. They are centered over the rebar, aligned with the splashboards, and secured in place using bracing to prevent shifting during the concrete pour. Once the Sonotubes are in position, concrete is added, and the brackets or other structural components are inserted to ensure proper alignment and support for the vertical columns.
The installation process involves precise measurements, careful alignment, and attention to bracing and leveling. These steps ensure that the resulting structure is stable, level, and capable of supporting the intended load.
Preparing for Sonotube Installation
Before beginning the installation of Sonotubes, it is essential to prepare the site and materials in accordance with the design specifications and construction plan. The following steps outline the necessary preparations:
Excavation and Footing Preparation: The site must be excavated to the required depth to accommodate the footings. The depth will depend on local building codes and frost line requirements. In the example provided, footings were constructed using 2' x 2' frames made of pressure-treated lumber and poured with concrete and gravel. The footings must be level and properly positioned to ensure the Sonotubes are installed at the correct location.
Rebar Installation: Rebar is placed within the footings to reinforce the concrete and provide structural support. In some cases, rebar is extended into the Sonotubes to connect the footing and pier, ensuring continuity in the foundation.
Sonotube Placement: Once the footings are partially cured, the Sonotubes are placed over the rebar. They are centered within the footing and aligned with the splashboards. The top of the Sonotube should be level with the top of the splashboard to ensure proper alignment of the vertical columns.
Bracing: To prevent movement during the concrete pour, the Sonotubes are braced in both directions using 2" x 4" lumber. This bracing ensures that the tubes remain in place and do not shift during the pouring process.
Alignment and Leveling: A level is used to check the alignment of the Sonotubes, ensuring that they are vertical and properly positioned. Any necessary adjustments should be made before pouring the concrete.
Installing Sonotubes in Pole Barns
Once the site is prepared and the Sonotubes are in place, the next step is to install the brackets and other components that will connect the vertical columns to the foundation. The following steps outline the installation process:
Installing Easy-Mount Clips: The center of each pier is marked on the splashboard using a pencil. Two additional marks are made 10 inches from the center to align the concrete forms. The easy-mount clips are then attached using roofing screws, with a speed square used to ensure they are vertical.
Attaching Sonotubes to Plastic Forms: The Sonotubes are attached to the plastic concrete forms using roofing screws. The sonotube should extend at least 6 inches below grade to ensure proper support.
Positioning the Plastic Forms: The plastic forms are attached to the inside of the splashboards at the marked locations. The top of the plastic form should be level with the top of the splashboard to ensure proper alignment.
Pouring Concrete: Using a specially designed hopper, concrete is poured into each form to the base of the Sonotube. The gaps between the soil and the Sonotube are backfilled to prevent the concrete from mushrooming out. The pier is then filled to the top of the concrete form.
Vibrating the Concrete: The concrete is vibrated to ensure proper settling and to remove air gaps and imperfections. This results in a stronger, more stable pier.
Inserting Brackets: Once the concrete has settled, the brackets are inserted into the concrete and slid into the easy-mount clips. This ensures that they are aligned and positioned correctly. A level is used to check that the brackets are straight.
Striking Off the Edges: The edges of the concrete are struck off to flatten the surface to the top of the form. Once all brackets are positioned, the concrete is allowed to fully set before proceeding with the next steps.
Connecting the Grade Board and Slab
In some pole barn constructions, a concrete slab is poured after the building is erected. This slab must be connected to the existing concrete and poles using wet-set brackets. The grade board (also known as a splash plank or skirt board) is oriented so that the upper 3-3/4 inches are above the top of the slab. In this area, 10d common galvanized nails are used. Below the top of the slab, two 3/16” x 3” Powers PC3DA-HDG galvanized steel split drive anchors (or equivalent) are used to secure the grade board to the slab.
To connect the concrete slab to the concrete in the Sonotubes, two five-foot lengths of ½” rebar are bent at 90 degrees at the center. One leg is placed into the Sonotube, and the other extends into the future slab area. This rebar is positioned at approximately 60 degrees from the plane of the splash plank. A short slot must be cut into the top of the Sonotube to accommodate the rebar.
This method ensures that the slab is properly connected to the foundation and that the structure remains stable and level.
Framing and Installing Vertical Components
After the Sonotubes are installed and the concrete has set, the next step is to frame the vertical components and install the columns. The following steps outline the process:
Setting the Columns: Each column is set into the bracket about 1 inch to allow for pivoting when lifted vertically.
Horizontal Framing: Horizontal framing is begun from the ground. Bracing boards are attached parallel to the splashboards and secured to the columns at predetermined heights. The tops of the columns must remain 8 feet on center or completely parallel from top to bottom, depending on the kit requirements. Corner columns are not framed at this stage and are installed later when the gable ends are attached.
Lifting the Walls: A lift is used to raise the eave sides and position them inside the brackets. The columns are temporarily secured using smaller lags until all walls are in place and the building is vertically squared.
Framing the Gable Ends: One gable end is framed and installed before the trusses are added. The corner column is installed and secured to the horizontal framing of the eave and gable walls.
Bracing and Alignment: Throughout the process, bracing is used to maintain alignment and stability. The building is periodically checked for squareness and levelness to ensure that the final structure is structurally sound.
Preparing Sonotubes for Pre-Placement and Anchors
For large-scale projects, it is often beneficial to pre-place and secure the Sonotubes and anchors before the concrete is poured. This allows the focus to remain on pumping the concrete rather than on adjusting the position of the anchors during the pour. To achieve this, the Sonotubes and anchors must be properly aligned and secured in place before the pour.
One method involves using bracing and temporary supports to hold the Sonotubes in position. The anchors can be attached to the Sonotubes using fasteners or welding, depending on the design requirements. Once the Sonotubes and anchors are in place, they are secured using bracing to prevent movement during the concrete pour.
This approach is particularly useful in projects involving a large number of piers, such as crawlspace replacements, where time and precision are critical. By pre-placing the Sonotubes and anchors, the construction process can be streamlined, and the risk of misalignment is reduced.
Backfilling and Curing
After the concrete is poured and the brackets are in place, the Sonotubes are left to cure. The curing time will depend on the type of concrete used and the ambient conditions. Once the concrete has cured, the Sonotubes are backfilled using a mini excavator or other suitable equipment.
Backfilling is done carefully to avoid disturbing the Sonotubes or the surrounding structure. The backfill material is typically a mix of soil and gravel, which provides additional support and stability to the foundation. The backfill is compacted in layers to ensure that it is dense and provides adequate support.
Once the backfilling is complete, the structure is ready for the next phase of construction, such as installing the deck posts, framing the walls, or erecting the roof trusses.
Conclusion
Sonotube installation is a critical step in the construction of pole barns and concrete foundations. Proper installation ensures that the structure is stable, level, and capable of supporting the intended load. The process involves careful preparation, precise alignment, and the use of bracing and leveling tools to ensure that the Sonotubes remain in place during the concrete pour.
By following the steps outlined in this article, builders can achieve a strong, durable foundation that meets the requirements of their project. Whether constructing a pole barn, a residential foundation, or a commercial structure, the use of Sonotubes can significantly improve the efficiency and accuracy of the construction process.