11.7: This straw bale research building at the University of Manitoba was designed by Kris Dick, and will be an important centre for alternative building materials testing.
Design professionals face challenges from many directions. Working with alternative building materials adds new dimensions to those challenges. For me, as a structural engineer, it creates an opportunity to work with many interesting people on unique projects, to apply fundamental engineering principles to non-traditional ways of building, and to explore the use of alternative building techniques through engineering design and applied research. However, some aspects of doing things differently can expand the boundaries of a design professional's responsibilities, both explicitly and implicitly.
Choosing to build a home is one of the biggest decisions many of us will make in our lifetime. Many of us are generally unfamiliar with all of the services, permits, scheduling, and finances that are a part of construction. One of the services usually required is that of a structural engineer. It is from the perspective of a structural engineer working with straw ^
The stamp of a structural engineer for straw bale home plans is a must in many jurisdictions. Structural engineers can work from completed plans or can often do the design and drafting work as well. They ensure that the plans, as drawn, are feasible, structurally sound, and meet code and safety requirements. The stamp of a structural engineer can help circumvent the concerns of a building official and allow you to get approval for your straw bale building plans. If you have drawn your own plans or purchased plans that require adaptations or minor changes, it may be better to take them to an engineer rather than to an architect.
Often known as an architectural technologists, a draftsperson has the skills and understanding to
11.8: You can blend other materials with your bale walls to good effect, like the stone base and wooden shelving in this sharply plastered wall.
bale structures that I would like to discuss what you should expect from a structural engineer, and what the engineer hopes you as the owner appreciate regarding their role and responsibility in the project.
A good place to start is where most projects begin, with a request for services. The phone rings, and a voice on the other end says, "We understand that you provide engineering for straw bale buildings. We're building a straw bale house, the building inspector says we need a seal, the plans are done. If I courier the plans to you tomorrow could I get a stamp in a few days? We're on a budget, I hope this won't cost much I just need a seal." While totally understanding the caller's situation, and willing to help, the engineer must address professional and legal responsibilities.
Constructing a straw bale house places the building outside of structural systems that are specifically addressed in the building code. In Canada, this means that a straw bale building must be evaluated based on a more rigorous engineering analysis, one primarily applied to commercial structures. This analysis is done in accordance with Part 4 of the National Building Code of Canada (NBCC). Due to the nature of the building materials used for a straw bale structure, it cannot meet the more prescriptive requirements of Part 9 of the NBCC, reserved for traditional residential buildings. In the case of a nontraditional building, the plan examiner or building official will require that the plans be "sealed" by a registered professional engineer. For those components of the building that do not have a specific reference in the building code, an equivalency of the proposed components must be demonstrated. Since there is engineering input required, the engineer responsible must affix their seal to all of the drawings associated with their design. Once an engineer puts their seal on a drawing, they are indicating to the pubic and the jurisdiction having authority that they are accepting responsibility for that portion of the project, and more specifically, any liability associated with it. ^
draw up quality plans but is not a licensed architect. A competent draftsperson has the training and knowledge to assist you with your design and your plans, from the initial stages through to completed construction documents, but he or she will not have the stamping powers of an architect or structural engineer. Still, a good draftsperson can be a valuable partner, and charges less than an architect.
Experienced builders can often draw up plans for clients, offering the advantage of minimizing mis-communication between designer and builder
Having the plans done before sending them to an engineer may or may not be a good approach, dependent upon how they have been done. There are industry standards for drawings that each engineer works to, and in some instances, there may also be certain details required by a local authority. By sealing a set of plans, the engineer is indicating the work has been done either by them or under their supervision. This is not to say that an engineer cannot review a set of plans done by someone else and seal them. The engineer must, however, perform an engineering review, request that any revisions be made, and when all is in order, seal them. If, upon review, there are numerous changes required to a plan set, it may be easier to have the engineering company make the changes. A change to one seemingly insignificant component often creates a ripple effect through an entire drawing set. If the original plans are in computer format, then it is a case of modifying the existing files to reflect the changes required. If the plans have been done by hand, then it may be a little more time-consuming to adjust the drawings. In some instances the engineer can create a separate set of drawings under their company name that can be appended to the plan set.
Involving the owner, engineer, building officials, and drafting personnel early in the design process can reduce time delays and minimize frustrations. Remember that, as the building season gets closer, all those involved typically get busy, resulting in unavoidable delays.
Naturally, with every service there is a cost. Every straw bale project is unique, requiring varied degrees of engineering involvement. Thus, it is impossible to estimate specific fees for engineering services. I would, however, ask the reader to consider the various roles and responsibilities of an engineer involved in a straw bale project and the value they bring to your project.
Some typical business costs, such as supplies, rent, support staff salaries, disbursements, and facility insurance, are reasonably straight forward to determine. The fees that are challenging to quantify are those related to the more intangible aspects of engineering service. When an engineer is requested to either prepare the design and plans, or review a design, there is an expectation that they will apply due diligence to the task. This expectation comes from not only their client but also the professional bodies through which all professional engineers must be licensed to practice. In the case of a nontraditional building designed in the absence of clear code guidance, the engineer must apply an analysis based on specialized knowledge gained and refined over time to meet a personal comfort level that allows them to take responsibility for their portion of a project. On occasion I have half jokingly said to people that for me this is a function of how high the acid rises in my stomach! It is difficult to place a value on years of study, experience, and a willingness to be legally and financially accountable for design decisions. As society becomes more litigious, one measure of cost might be to look at the amount of liability insurance design professionals pay. For example, at the time ^
and the disadvantage of having fewer people's thinking applied to the plans.
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