For Contractors
What about engineering?
When is engineering required?
• Retaining walls which retain more than 4 feet of material.
• New, repair, or replacement of decks over 12feet high.
• Bridges
• Construction other than conventional, wood framing, per UBC 2320.
• Buildings of other non-standard construction, including split-level buildings and buildings of unusual shape, per UBC 2326.
• Non-standard foundations, including pier and grade beams.
• Trusses.
• Large load-bearing beams, including glu-lams.
• Large or high strength timber connections.
• Water storage tanks over 5,000 gallons (to include foundation and anchorage to foundation).
• Grading more than 2,000 cubic yards
• Swimming pools.
• Special Inspection and testing schedule.
• Contour mapping when required per building height
What are the benefits to working with an Engineer?
• Save time, money, and resources!!! It is a good idea to get the engineer involved at an early stage, as the engineer is often able to find ways within the project to be more economical with your and your client’s resources, time and money.
• Codes are constantly evolving!!! Another important reason you want to work with an engineer is that codes are constantly evolving. You have a construction crew to manage and many other important tasks to accomplish, so utilize the engineer’s expertise with codes. It is the engineer’s job to stay current, ensuring your project will not only stand up, but will meet the most current building codes and standards. Help minimize your liability!o As a simple example, the engineer can appropriately size the beams, holdowns, and connections you need so you don’t spend extra money on materials you don’t need.
What else do I need to know?
Why is it engineered that way?
• Shear Walls – are designed to transmit lateral (horizontal) loads from wind and seismic forces to the foundation system to prevent the structure from collapsing in an earthquake or heavy wind. There are many different types of systems (lateral force resisting systems), including conventional plywood shear walls, pre-fabricated shear walls (Simpson Strong-Walls, Hardy Panels, etc.), and steel frames.
• Framing Connections – are one of the most significant developments of the last 50 years. They help to create a complete load path that ties all components of the structure safely to the foundation, ensuring that the structure will withstand loads from wind, earthquakes, and gravity.
• Anchors – are an essential component used to tie the structure to the foundation. It is important to use the anchors specified by the engineer, because different types of anchors have different capacities intended for different uses.
Frequently made mistakes in the field:
• CLR vs. MIN – It is important to understand the abbreviations used on the plans. For example: CLR means clear, which means the distance between the edge of the concrete and the edge of the reinforcing. It is an exact dimension and is not to be confused with MIN. MIN means minimum, which means the dimension cannot be less than the specified number, but can be larger. These differences make a difference in the strength of the concrete. See Rebar Location below. When in doubt, ask the engineer for clarification!
• Rebar Location – The strength of a concrete structure depends on the distance between the edge of the concrete and the reinforcing steel within. Concrete is very strong in compression, but without the steel reinforcing it has very little tensile strength. It is not enough to just put the steel in the concrete; it must be in the correct location to resist the tensile forces. See CLR vs. MIN above.
• Holdowns – have evolved quite a bit in the last decade, so use of currently designed holdowns is important. It is important to use the holdowns specified by the engineer, because different holdowns have different capacities. They also require the proper corresponding anchor bolt. Mismatched holdowns and anchor bolts can lead to a failed structure.
Construction Observations
Typically the engineer will be involved with the project from the beginning and on through the construction phase. You will likely have questions and the engineer will help you correctly interpret the design. During this time, the engineer should also visit the project site to review or observe certain pieces of the construction, such as reinforcing and anchor bolt locations prior to pouring concrete (see: frequently made mistakes). The engineer should also observe shear walls and framing connections. In many situations, these observations are also required by the building code. These site visits by the engineer are extremely valuable because they often help you avoid costly mistakes.
Special Inspections
In addition to inspections by the Building Inspector, the Building Code requires Structural Tests and Special Inspections of certain types of components. Welding, high strength concrete, and epoxied anchors are some examples of these components. There are many other situations that require these tests or inspections. These will be determined during the design process. It is important for you to know when these need to happen, so they don’t get missed. The project engineer may be able to perform some of these inspections, while others require a Recognized Special Inspection and Testing Agency.
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