Engineering:Residential frame engineering

Residential frame engineering typically involves the structural engineering design of the frame structure of a house. Rather than a set of structural plans drafted by an architect or lumber supplier, engineered framing plans are developed by a licensed engineer.

Drawings

A typical set of engineered drawings for a house will include: Roof framing, Ceiling joist framing, Floor joist framing, Wall bracing and General notes and details.

Roof framing

The level of detail to which a roof system is engineered varies greatly among engineers. At a bare minimum, the roof framing plans should show the rafter layout, specify the size and spacing of the rafters, and specify the allowable span of the rafters. Some engineers today provide only this minimal amount of detail on the roof framing plans they generate. Other engineers provide a much higher degree of detail. In addition to the items mentioned above, they show the location of all roof supports (i.e. struts) and show all purlins with dimensions to tie down their location. Generally speaking, the more detailed the roof framing plan, the higher quality the roof frame engineering.

Ceiling joist framing

The ceiling joist layout shows all of the ceiling joists over the rooms (typically over the second floor of a 2-story house, or over the first floor of a 1-story house). The size of the joists will vary depending on the spacing of the joists, as well as the span. Whether or not the joists are designed for attic storage loads will also affect the size of the members.

Depending on the location of the project, the type of lumber used may vary. The allowable spans for several common lumber species can be found in the 2015 International Residential Code, published by the International Code Council.

Floor joist framing

The floor joist framing layout looks similar to the ceiling joist layout. However, where the ceiling joists may consist of 2x6s, 2x8s, 2x10s and 2x12s, the floor joist layout will typically show 2x12 joists only. In some cases, where loads and spans dictate, and deeper floor joist system may be required. Deeper floor systems include wood I-joists and open web trusses.

Wall bracing

Wall bracings plans specify the amount and type of sheathing or lateral bracing that is needed for the house to withstand the applicable design wind speed. In higher wind speed areas, the wall bracing plans may additionally specify embedded or post-installed hold-downs, pre-fabricated steel wall panels, steel moment frames, etc.

General notes and details

The general notes and details will contain standard construction recommendations and typical construction details. General notes and details provide information that supplements the structural drawings.

Benefits

There are several benefits to having residential framing plans engineered. Some of these benefits include:

1. Load path analysis to ensure roof loads are properly and efficiently transferred down to the foundation
2. Value engineering - beams with significant spans are designed for bending capacity and their deflections are checked using engineering analysis, and are not simply taken from a table based on historical precedence
3. Value engineering means better performance while minimizing costs
4. Fewer delays obtaining permits and during construction
5. Peace of mind knowing the structure complies with code and sound engineering principles