Value of a Structural Engineer
Why would you hire a structural engineer to design your house? Shouldn’t building contractors know how to build a house? How expensive is it to hire an engineer? All very good questions!In a world of ever-changing building codes and the creation of elaborate, open floor plans of today’s custom houses, design and construction of residential properties can be complex and difficult. Complexities arise in the structural framework due to open floor plans reducing the ability to stabilize the structure, openings in exterior wall frames for the installation of larger doors, windows, case openings, bay windows, and on and on. As the building design opens for these features and amenities, the ability of the structure to handle the imposed loads (gravity, dead loads, live loads, wind loads, snow loads, seismic loads, etc…) becomes more challenging.
Often, house plans are submitted to lumber yards and/or truss manufacturers for material quantity take-offs and truss designs, respectively. House plans are often designed in accordance with prescriptive building codes while deferring select structural beams and frame features to the “manufacturers” of the beams and frame features. Manufacturers do their part in the structural design of the beams and frame features, but they may not look at the whole house structural design.
When your house plans are completed by your designer or architect, a structural engineer should be considered to design the structural framework and foundation of your house. A structural engineer, experienced in the structural design of residential properties, can design the necessary details to meet the code requirements for your house using computer programming and technology. On houses with complex roof designs, open spaces, and/or elaborate spacial configurations, a structural engineer can be a huge asset in providing a design for a structurally sound house.
A general scope of work for a structural engineer may include:
- Type, size, and location of all beams
- Material identification, sizing, and spacing for wall, ceiling, floor, and roof systems
- Connection details for walls, ceilings, floors and roofs
- Wind resistant strap identification and location
- Anchor (nails, screws, bolts) details
- Special Framing Details needed for construction.
Sample Structural Frame Layout
Subject to legal opinion and consideration, building contractors are generally required to construct a house in accordance with the plan provided to them and in accordance with local building codes. That being said – custom house plans have varying degrees of “completeness” with many construction details subject to opinions and/or experience of a contractor. In other words, “grey areas” may, and often do, arise when constructing a house. In an elaborate house, reliability of the contractor’s experience and project management prowess are essential for proper construction. It is these “grey areas” where the value of a structural engineer is most exploited. A structural engineer may best help in these unusual circumstances by providing a structurally sound framework system. Structurally compromised framework often leads to excessive deflection of the frame, fractures in the framework, out-of-plumb features in the house, and/or wall and ceiling cracks on the interior and exterior of the house.
The cost of hiring a structural engineer varies from region to region and market conditions. In perspective, custom residential houses are often more complex to construct than commercial buildings of comparable size. However, commercial buildings must have a licensed professional (architect or engineer) be in responsible charge of the project according to governing codes. Also, in accordance with most building codes, residential houses DO NOT have to have licensed professionals in responsible charge. Objectively, one should consider a structural engineer cost of 1% or less of the house value for the general services listed above.
Acknowledging structural engineers may not be necessary for the design of smaller houses, large custom houses often have unique structural conditions that are best managed by a structural engineer. A structural engineer may prove valuable in providing a structurally sound design for the framework of your house, which will serve to manage structural anomalies and time in the construction of your house.