Structural, energy and other technical requirements

Beyond fire safety, egress and accessibility, codes regulate how buildings stand up, how they keep out water and weather, how much energy they use, and how their plumbing, heating, ventilation and electrical systems are built. These requirements are largely the domain of engineers and specialist designers, but construction managers deal with their consequences: structural design loads drive the size of members and connections, energy rules drive insulation, windows and air barrier details, and plumbing and mechanical rules drive rough-in layouts and inspections. This lesson gives an overview of each area, enough to understand the code basis of the design and to recognize when a site decision may affect compliance.

The structural design itself is covered in CON-240 Structural Systems for Construction, and envelope materials in CON-111 Construction Materials and Methods II. Here the focus is on what the code requires and how compliance is shown and checked.

Structural design requirements

IBC Chapter 16 governs structural design and references ASCE/SEI 7, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, for most loads; the 2024 IBC references ASCE 7-22. Buildings are designed by strength design (load and resistance factor design) or allowable stress design using load combinations from ASCE 7, with member design from material standards: ACI 318 for concrete, AISC 360 for steel, the AWC NDS for wood and TMS 402 for masonry. Loads include dead, live, roof live, snow, rain, wind, earthquake, flood, ice and tsunami where applicable. The ASCE Hazard Tool provides site-specific wind, snow, seismic and other hazard values.

Buildings are assigned a risk category from I to IV based on the consequences of failure. Risk Category I covers buildings with low hazard to human life, such as agricultural buildings; Category II covers most buildings; Category III covers buildings with large occupant loads, such as schools and large assembly buildings; and Category IV covers essential facilities, such as hospitals, fire stations and emergency operations centers, which must remain operational. The risk category affects design loads for wind, snow, seismic and other hazards.

Site decisions can affect structural compliance. Storing heavy materials on a roof or floor before it is complete, cutting holes in joists or beams for services, substituting a different connector, omitting temporary bracing or changing the sequence of shoring removal can all overload or destabilize a structure. Construction managers should route any such question to the structural engineer of record and keep a record of approvals. Structural safety during construction is also regulated by occupational health and safety law and by provisions for temporary works.

Environmental separation and the building envelope

IBC Chapter 14 governs exterior walls, including weather protection, water-resistive barriers, flashing, vapor retarders by climate zone and materials such as cladding, metal composite panels and exterior insulation and finish systems. Chapter 15 covers roof assemblies and rooftop structures. Air barriers are required by the energy code. Sound transmission between dwelling units is controlled by IBC Section 1206, which requires a sound transmission class (STC) of 50 (45 if field-tested) for walls and floors separating units and an impact insulation class (IIC) of 50 for floors.

Envelope details are where many construction defects arise: leaks at windows, condensation in walls, ice dams and mold. Codes set the minimum, but performance depends on continuity of the air barrier, water-shedding laps and flashings, and correct sequencing of trades. Mock-ups and field testing, such as window water testing and whole-building air leakage testing, are increasingly required by owners and, in some energy codes, by the code itself.

Energy codes

Energy requirements come from the International Energy Conservation Code, adopted by states with amendments; for commercial buildings, ASHRAE Standard 90.1 is an alternative compliance path. The 2024 IECC and ASHRAE 90.1-2022 are the newest editions; adoption varies widely, with some states still on much older editions and others, such as California with its Title 24 Part 6 standards and Washington with its own energy code, going well beyond the model codes. Federal law requires states to certify their commercial energy codes against recent ASHRAE 90.1 editions. Compliance may be shown by a prescriptive path (maximum U-factors and minimum R-values by climate zone, and equipment efficiencies), a component performance or trade-off path, or a total building performance path using energy modeling, and the 2021 and 2024 IECC require additional efficiency credits for commercial buildings.

Energy codes have changed construction practice more than any other part of the code in recent years: continuous exterior insulation, thermally broken window frames and cladding attachments, high-performance glazing, air barrier testing, controls for lighting and heating, and heat recovery ventilation are now common. Construction managers must protect the details that deliver the energy performance, because substitutions of windows, insulation or equipment can change compliance. Energy code inspections, testing reports and commissioning documentation are often required before occupancy.

Plumbing, mechanical and electrical codes

Plumbing systems must comply with the International Plumbing Code or, in some states, the Uniform Plumbing Code, which govern drainage, venting, water supply, backflow prevention and fixtures; the required number of fixtures is set by IPC Table 403.1 based on occupant load. Mechanical systems must comply with the International Mechanical Code or Uniform Mechanical Code and the International Fuel Gas Code, with ventilation rates based on ASHRAE 62.1. Electrical installations must comply with the National Electrical Code (NFPA 70) as adopted, with permits and inspections by local or state electrical inspectors. Elevators must comply with ASME A17.1, usually enforced by state elevator inspectors.

Other technical requirements

Codes and related regulations cover many other technical matters: protection against radon and soil gas, which recent editions have extended; protection from falling at guards and windows; safety glazing in doors and near floors; elevators and lifts; signage; and, increasingly, climate resilience measures for flooding, wildfire and extreme heat. Construction sites themselves are regulated: demolition, excavation, hoarding and protection of the public and adjacent buildings.

IBC Chapter 33, Safeguards During Construction, covers protection of pedestrians with barriers and covered walkways, protection of adjoining property, fire safety during construction and stairways in buildings under construction. OSHA regulations govern worker safety.

Climate resilience and emerging requirements

Recent editions and state amendments have begun to address resilience to climate hazards. ASCE 7-22 updated snow, wind, flood and tornado provisions, and the 2024 IBC references tornado loads for Risk Category III and IV buildings in tornado-prone regions. The International Wildland-Urban Interface Code, California's Chapter 7A and similar state rules require ignition-resistant construction in wildfire areas, and flood-resistant construction follows ASCE 24 in flood hazard areas. Construction managers should expect more requirements in these areas in future editions and local amendments.