Tech Talk: CFA Certified Cast-In-Place Foundation Contractor Program
By: JIM BATY, CFA Technical Director
Part II: Beginning in the summer of 2008, the Concrete Foundations Association (CFA) will unveil a new industry program to certify foundation contractor firms in the residential cast-in-place industry. This article in the six-part series provides greater depth to the knowledge component of the program. Preparing for the evaluation of basic levels of technical understanding and understanding the required levels of continuing education is the first step that companies face as they enter the process to become certified. The goal of this certification is to unify the industry toward the goal of a common measurement of competency for concrete foundations and the companies that install them.
It might be surprising to many outside the concrete foundation industry that the level of knowledge and the expert understanding of concrete science and engineering is one of the greatest assets of a great number of professional contractors. The residential industry has been considered less significant in many parts of the country for years than its commercial counterpart and therefore, little scrutiny has been placed on the contractor’s ability to make quick decisions as conditions change in a design or a site.
The CFA Company Certification Program establishes a significant evaluation of the corporate knowledge for the most fundamental areas of foundation design and construction. This component has been referred to as the Basic Knowledge of Concrete and Foundations, while it actually extends beyond this scope to affect the wholeness of basement systems that are put in place today. Let’s take a look at some of the physics and construction science areas and begin to understand why they are so important to this initial step in the certification process.
Concrete is the most widely used construction material in the world. It has been used since Roman times and continues to perform to this day. Buildings and foundations constructed of cast-in-place concrete have performed flawlessly under the recent onslaught of natural and manmade disasters. Hurricanes, tornadoes, and fires may destroy the less durable parts of the structure but the foundation for building anew is already in place.
Even though concrete has such historical presence, today’s concrete is far from the same product that continues to withstand the test of time. It is higher in strength and often a mixture that resembles a chemistry lab experiment rather than the inert aggregate matrix of old. Companies today must understand the impact of water in the mix more fully. They must recognize the differences between products that are added at a controlled Ready Mix plant versus products that are added on site and how this alters their ability to modify mixes for workability or to “stretch” loads.
Companies that enter the evaluation phase will demonstrate their understanding of the measured properties of concrete as well as the mixture components. They will identify the important testing procedures that qualify concrete mixtures and provide evidence for the ways that performance can be predicted as well as verified. Today’s codes and standards are very specific in their requirements for concrete strengths and yields. Therefore, foundation companies must be able to identify the variations that these specifications produce and be prepared to demonstrate their ability to maintain these performances throughout the duration of the construction process. This includes the ability to preserve or protect the early-age performance which is the most critical time in the maturity cycle of the structural concrete.
Perhaps the area of the business that is most susceptible to change from the start of the project to the end is soils. Understanding the differences in soil classifications and the responding bearing capacities as well as pressures will often determine the success of a foundation over the life of the structure. A foundation wall, for instance, that is designed for soils the produce 45psf of pressure; suddenly introduced to soils that actually apply 90psf of pressure may be at risk for excessive stress.
The contractor must be cognizant of the locations for information on soils and when it may be necessary to seek physical evidence of the anticipated soil performance. Local knowledge is certainly useful but as development continues, the impact to any local or regional soil may be drastically altered over decades of altered run-off and replacement.
Similarly, the performance of the soil can alter the stability of the actual foundation structure when the full bearing pressure is applied. Contractors must also be able to identify soil variation and have the necessary understanding of remedial efforts to maintain the stability of the structure.
Footings & Foundation Walls
The next significant sections for the basic knowledge evaluation deal with the majority of structural concrete that is designed and constructed on these residential projects. Concrete footings are more than the setting pad for the removable or the insulated concrete forms; they are the primary structural elements that transfer loads from the entire house structure to the sub-grade. There are minimum geometric requirements for footings as well as minimum connection requirements from the footings to the concrete foundation walls they support.
A concrete footing takes many forms depending on their location in the structure as well as the region of the country. In structures where bearing elevations vary, contractors must recognize the structural requirements for these changes in elevation and where footings are required or not.
The foundation wall is the principle design element for the sub-grade structure. Wall height, unbalanced fill depth, footing connection, deck connection and the foundation geometry itself, all influence the structural configuration for the foundation wall. Contractors must be able to identify the variability in the characteristics of the foundation wall as well as the response of the required wall design to the variety of codes that may be enforced. In addition, the importance of horizontal steel reinforcement must be understood and the ability to determine the required spacing and minimum quantities demonstrated.
The job for most foundation contractors today does not end when the forms are removed from the walls. After the forms are stripped, the fresh wall is now ready for the application of dampproofing or waterproofing. The variability of these applications is largely code based, however, contractors will demonstrate their understanding of the differences in performance when a wall is left untreated or receiving one of these applications.
Contractors will identify with the reality that aside from crack development, the number one factor in customer satisfaction is whether walls prevent the presence of moisture. Therefore, being able to demonstrate the reasons why the selection of dampproofing over waterproofing is also important through this process.
Depending on the level of treatment of the walls and the quality of that application, the performance of surface and perimeter drainage will impact the success of the foundation the most. Therefore, the next level of evaluation deals with the requirements of surface drainage away from the house foundation as well as the options for drainage systems at the base of the foundation walls. These systems collect water that seeps through the soil next to the basement and directs it to a sump system where it can be pumped to above ground drainage. Proper design and installation of these sub-soil drainage systems are essential to their long term performance and are also often the reason why so many result in failures and call-backs.
The walls are finally prepared with forms stripped and coatings or membranes and insulation applied. The foundation contractor is nearly finished or perhaps the builder has even taken over the responsibility. The single largest factor in poor foundation performance is what happens at this next step, backfilling. Therefore, the evaluation of contractor knowledge on the proper methods for protecting the foundation wall during the backfilling procedure, the proper backfilling steps and the types of acceptable backfill material is essential.
It is true that carpenters can begin the next day after the foundation walls have been stripped and treated but care must be taken to make sure that the combined interest of the builder for fall protection and the protection of the early-age concrete walls are observed. Contractors will demonstrate where backfill can be placed to the desired grade height and where it must be staged or stepped until further protection exists. Contractors will demonstrate their understanding of the designed performance for foundation walls and why walls must have lateral connections at both the base and top of the wall before full backfill is applied.
As the backfill stages are completed, the final grade is the final significant factor in the long term performance of the foundation system. Poor backfill procedures lead to final grades that settle with time and create negative slopes to the walls. Contractor knowledge of the required minimum positive final grade slopes will ensure that their installations are finished with the quality that was put into the walls themselves.
Concrete codes have evolved significantly in the past decade with much more widely recognized value to the performance of plain structural concrete. Contractors, however, must also fully understand the prescribed steel reinforcement minimums and when they apply. During the evaluation, contractors will demonstrate the ability to determine the prescriptive requirements for these foundation walls based on the design information presented.
Demonstrating knowledge of the various building codes that may impact their projects will prepare contractors to also identify the opportunities that exist in producing the most effective foundation systems. There are many advantages that can be found through a more detailed knowledge of the applicable codes as well as when one code can be left in preference for another.
In all, there are eight areas of knowledge that contractors will demonstrate as they prepare for and finish the knowledge evaluation component of this certification program. The seven identified above along with Safety, to be presented in a later article are essential to the success of foundation companies and the quality of foundation systems.
Contractors will be able to prepare for the evaluation process with key publications available through the CFA and other sources. These publications include the International Residential Code; Requirements for Residential Concrete (ACI 332) by the American Concrete Institute as well as the corresponding Guide to Residential Concrete Construction; and the CFA Standard by the Concrete Foundations Association. Each exam will be preceded by an in-depth seminar that presents many of the fundamentals covered through the exam in a classroom setting where contractors can challenge these principles and components as well as solidify their understanding.
Once a contractor representative has successfully completed the certification exam, there will be an annual requirement of continuing education for a minimum of two individuals in the company. This education is required to be in the areas of Codes and Materials and Materials and Methods.
Company representatives will be able to attain their required CEU hours through a wide variety of sources. The CFA will maintain a minimum of four hours for this content at each Annual Summer Convention. The program will recognize certain presentations from the World of Concrete each year on a pre-approved basis. In addition, local and regional courses offered through or in conjuction with the CFA such as Foundation Fundamental seminars, Tool Box talks, pre-approved locally sponsored seminars by builders groups and other industry segments will also apply towards this requirement. It is in the best interest of participants to have educational requirements spread over several individuals in the event someone leaves the company.
The knowledge component of the CFA Certification Program has been established to validate a minimum understanding of the science and practice of the residential concrete industry. Certified contractors will not only meet this minimum understanding, they will be required to continue pursuing growth in their knowledge base and provide this development throughout their company as they broaden the number of employees exposed to this essential information. If you have any comments or suggestions about the requirements or details of the program, make certain you contact either Dan Bromley, CFA Certification Committee chair (816-795-0072 or DanB@ABI-Corp.com) or Ed Sauter (319-895-6940 or firstname.lastname@example.org) to make your ideas known.
Established in 1974 for the purpose of improving the quality and acceptance of cast-in-place concrete foundations, the CFA offers a variety of resources on topics ranging from residential foundations to above-grade homes, commercial market opportunities to alternative markets. CFA efforts have produced considerable promotional materials, educational seminars and networking opportunities that place members in one-on-one contact with experienced peers for assistance in resolving a variety of issues. The CFA and the structured Concrete Homes Council (CHC) represent the interests of its members and the industry on several code and regulatory bodies, such as the American Concrete Institute’s 332 committee – responsible for the creation of the “Residential Concrete Standard.” The CFA has several of its members on the ACI committee responsible for this document and will endeavor to ensure that the interests of the foundation contractor are considered. For more information about CFA, see cfawalls.org or call (319) 895-6940. For more information about CHC, see concretehomescouncil.org or call (319) 895-0761.
Jim Baty, email@example.com, is Technical Director of the Concrete Foundations Association and the Concrete Homes Council.