There are many foundation options for your steel structure. For buildings that require more storage or living area a basement or a crawl space is a great addition. However, for owners who are looking to save money and do not need the extra room, a concrete foundation is a perfect choice. Concrete provides a solid, even foundation for your building to rest on, and provides the best possible surface in which to solidify your anchor bolts. However, if your concrete slab is not laid correctly issues can arise down the road. In order to provide your building solid support for years to come there are several criteria, your new concrete foundation must meet.
Adherence to all Federal Rules and Regulations
Several government organizations, such as the Occupational Safety and Health Administration (OSHA) and state-based Departments of Consumer Affairs provide strict guidelines for the requirements of concrete foundation slabs. Following these guidelines will both ensure that your structure is legal and that it meets all best practice guidelines.
These departments also provide safety guidelines for laborers involved in the laying of concrete foundations to be sure you and your workers are protected during the process.
Some of these safety guidelines include:
When working with concrete, if the dust and fumes from the setting concrete exceed a certain level a respirator must be provided for each employee and a preliminary medical exam must be performed by a licensed practitioner to confirm each employee is eligible for safely wearing a respirator. If a respirator is not required employees must be allowed to bring their own respirator if desired. Each respirator must be checked for fit and damages before being worn on site.
All employees shall be provided the appropriate face and eye safety wear and all pieces must fit correctly and without damage. This safety wear must be disinfected after each use and special provisions must be made for individuals who wear vision correcting glasses. Eyewear must protect against radiant energy when appropriate. If there is danger from falling items or electrical shocks all employees on site must be provided, and wear, the appropriate head protective gear at all times.
The employer is responsible for ensuring all employees have had sufficient accident training, and emergency plans are in place and understood by all employees. The employer is responsible for regular safety inspections of the job site, and must document all ‘hazardous’ situations and ensure the correct authorities are notified of potential site hazards. All machinery must be safety inspected and display the correct identification and tagging to prove it is within the defined calibration dates.
- Respiratory Protection
- Proper Eye, Facial and Head Protection
- Accident Protection
To learn more about safety guidelines, read our construction site safety guide.
Techniques for Laying Concrete
When it comes to laying the concrete foundation for your building there are several popular techniques that construction professionals use, including the Cassion technique, laying the foundation in panels, and the standard concrete laying method.
Using the Cassion Technique for Pouring your Concrete Foundation
The Cassion Technique involves laying your concrete foundation and anchoring your steel building at the same time. This method provides added stability for your building but also makes any structural adjustments or additions very difficult. The Cassion technique involves digging holes around the perimeter of your building for the anchor rods. These holes should be approximately 10 inches wide and at least 30 inches deep (if your land has a frost line be sure the depth of your anchor bolts extends at least 12 inches below the frost line). Then place the anchor bolts in these holes and simultaneously pour the concrete. Then use a 2 x 4, or specialized equipment, such as rollers for larger areas, to set and level the concrete. If you desire an extra smooth finish for your concrete foundation use a trowel to smooth out the surface after all concrete has been leveled.
Laying your Concrete Foundation in Panels
Laying your concrete foundation in panels is a quick way to lay a concrete foundation while still providing suitable support for your structure. Using this method the area of your foundation is divided into panels, no bigger than 2 square meters, using strips. These panels must then be filled-in alternately to ensure the weight of your structure is evenly dispersed while reducing the chances of shrinkage cracks. After all panels have been filled level the concrete with a straightedge and smooth over with a 2 x 4.
Using a Standard Concrete Laying Method
This method allows you to place anchor bolts in the foundation later on and provides added support by including footings, or excess concrete around the perimeter of your building. In this technique, the footings and the concrete base itself are poured at the same time. The slab and footings should be at least 0.5 feet thick, and footings should extend at least four to six feet beyond the square footage of your building on all side. This extra overhang will prevent the concrete from cracking when you place the anchor bolts in the foundation.
Checking the Foundation is Solid
Now that your foundation is in place, it is important to check that it was laid properly without any errors to ensure the sustainability of your concrete. The best time to check your foundation is at least 28 days after the initial foundation was laid. This gives the concrete time to fully dry and settle into place. Any cracks or adjustments that may occur during the time the concrete sets will most likely have taken place by now. First, inspect your concrete for strength. Check extensively for any visible cracks in the surface. Cracks may appear while your concrete is settling due to a fluctuation in outdoor temperatures and humidity during drying time, drying shrinkage on the surface of your foundation or subgrade settlement. While cracks are not desirable, they are not always a cause for concern. If your crack is smaller than 1/16″ in width than most likely the damage is only cosmetic. If the crack is larger it is better to seek assistance and consider repairs. Secondly, check the foundation is level. Use a straightedge to ensure all concrete settled evenly and there are no outlying high or low points on your foundation, which could damage the structural integrity of your building. Lastly, ensure your foundation is properly shaped. Look at all edges and make sure they are sharp and clean. Measure diagonally across the foundation to check that all dimensions are correct and each side is of equal length.
As always remember to consult your local building authorities to ensure you are following all your state and local building codes when creating your foundation for your steel or metal building.
Author: Conrad Mackie