When approaching a major renovation, there are two structural components that should never be dismissed just to achieve your client’s dream home: load bearing walls and roof structures. Although the consequences of removing a wall or renovating an attic into a loft may seem minimal, if either are ignored it can hinder the structural integrity, which the architect or contractor could be found liable if done negligently.
Load bearing walls are fairly self-explanatory. They are the walls that carry the weight of the home. These are structurally engineered not only to bear the weight and stress of a home but also to resist earthquakes, heavy winds, and other weather-related events.
As for structurally engineered roof systems, there are two options: prefabricated roof trusses and conventional stick framed roof. Trusses are built at the manufacturer’s facility and can be customized to fit any scope of project. These are often stronger and more efficient than stick framed roofs, as they utilize a system of interconnected framing members which band the roof and ceiling together. This system causes all the relatively small members to act as one taller structural member, which increases its strength and stiffness and allows the total weight of the roof to be fairly light in comparison to its strength. Prefabricated trusses are critical to the development of structurally sound buildings (residential and commercial) and similar concepts are used in bridges as well.
In comparison, stick framed roofs are built on-site by the contractor and are constructed by cutting and placing each rafter or ceiling joist one at a time. Although not as strong and efficient as trusses, stick framed roofing is often considered easier to manipulate (either later on in the construction or even later during a renovation), but many architects and homeowners are opting out of this style for a few reasons. First, stick framed roofing takes up a considerable amount of room on-site (room that could be used by other contractors working on different areas of the home). Second, working on-site relies heavily on the right weather conditions – rain, wind, mud, and extreme heat are all negative factors when building stick-framed roofing. Third, stick framing increases the time and amount of lumber needed to complete the roof.
Understanding the basic fundamentals of both load bearing walls and roof trusses will help paint a clearer image of why structural engineers are imperative to these types of renovations.
Although renovations are seemingly normal these days, home improvement shows and DIY websites don’t accurately depict the entire story. It can be extremely dangerous (as well as detrimental to a home’s resale value) to begin a renovation without the guidance of a Structural Engineer. In California, most types of renovation projects require a Structural Engineer in order to be approved and permitted by the Local Building Department. If one fails to follow protocol in obtaining a building permit, the homeowner can get red-tagged and/or be liable for fines. Structural engineers are there to work with architects to help homeowners through this permit process, as their stamped and signed structural plans (which enforce construction and safety codes) are exactly what the Local Building Department needs.
LOAD BEARING WALLS
Most commonly these days, homeowners are looking to create an open floor plan, requiring partial or full wall removal(s). While removing load bearing walls is not impossible, understanding which walls are load bearing (and which are not) is not as straightforward as one might think.
As we know, load bearing walls carry the home’s weight (from the roof all the way down to the foundation) and protect the home from environmental factors. It’s critical to have a reconstruction or renovation plan completed by an engineer in order to ensure the building’s structural integrity will be restored (in the event a load-bearing wall is indeed removed). However, these load bearing structures get a bit trickier when there are two or more stories involved. If a homeowner wants to create an open floor plan on the ground floor but keep the overall structure on the top floor the same, the structural integrity will be jeopardized if not engineered by a Structural Engineer.
Structural engineers are able to look at a home’s original plans in totality and determine which walls can be safely removed and which load bearing walls need newly drafted construction plans for permits. In the event that the original blueprints are not available, an on site visit by an engineer is then needed in order to determine the structural renovation needs. We highly recommend to all home improvement professionals to never assume an interior wall can be removed, as it might be important to the overall structure and safety.
TRUSS ROOF SYSTEM
When it comes to skylights, this is a bit easier as an engineer can accurately depict where the incisions can be placed without creating stress or harm to the trusses. Renovating an attic space, however, can be much more difficult and involve a lot of reconstruction as it all depends on what style of trusses have been installed (more on this, below). For both minor and major roof and ceiling renovations, a Structural Engineer will be your go-to person to ensure the design plans are A) possible, B) compliant with state and city safety codes, and C) are structurally sound.
Open plan and storage style trusses are the easiest for architects, engineers, and contractors to convert into another bedroom or loft. The trusses have already left plenty of space ready to be used, and while still needing permits, they will not be as complex and the overall construction cost will be lower. If the home has a closed-in roof truss, such as King post, fan, or howe for example, the entire truss construction will need to be redesigned in order to fit your design plans.
• This may be the most obvious one, but to ensure a safe structure for those living in and around the home.
• In California, most structural constructions, reconstructions, renovations, or alterations must be stamped and signed by a licensed engineer and permitted by the Local Building Department.
• Not obtaining the necessary permits and documents can result in major devaluation of the home’s resale price or create potential issues if the homeowner wants to renovate again later on.
• Create “as-built” drawings based on what is visually observable to replace any inaccurate or lost blueprint originals.
• Prepare a stamped set of structural drawings for the removal of load bearing walls and/or roof truss reconstruction.
• Prepare an analysis for wind, seismic, and gravity forces according to current California Building Codes.
• Provide a calculations book for vertical, wind, and seismic loads required by the Local Building Department.
*Note: The content published above was made in collaboration with members of Design Everest.