Capture savings through resource efficiency
You may have read in the morning paper or noticed at the pump that the price of gasoline is on the increase again. If you drive very far to your job sites it may already be affecting your bottom line enough that you are really starting to feel it. In the construction industry, the cost of energy impacts a lot more than the price of filling up your gas tank. Every other person who works on those job sites is also facing the same increased costs of getting there. Every piece of equipment used for excavation and materials handling now costs more to be trucked in and out and is operating on site at a higher cost. Every component, no matter how small, that is used to assemble the building is trucked in from somewhere at those rising fuel prices. Before shipping, all of those building materials were manufactured from natural resources or recycled resources in a plant somewhere using still more energy. Could using locally or regionally produced products reduce the cost? How far has each product used in a home traveled from its point of origin or manufacture? Just pick up any item on a construction site and consider the source of its components, including the resources and energy required to put it in your hand. Is everyone on your project team thinking about improving resource efficiency? Should they be?
Photo by Richard Stone, University of Minnesota
There are opportunities for increased resource efficiency at every stage of new home design and construction. Excess materials are removed at the design stage by architects and designers who integrate resource efficiency and durability concepts into construction details and specifications. Plans with this level of detail lead to more accurate material take-off lists and on-site execution of the work, saving time and materials. When I began the shift to "advanced framing" over twenty years ago, our electrical contractor told me that the changes made our homes a lot faster to wire because of the detailed specifications and reduced amount of lumber that he had to drill and pull cable through. That provided an additional cost savings that I had not anticipated. It also showed me that there were additional advantages to be gained by planning thoroughly and keeping to the plan instead of allowing mechanical system design to be determined on site based on the space and materials that happened to be available on any given day. We started with small changes and then, as our comfort level increased, expanded our application of the principles, identifying new opportunities to reduce cost and at the same time improve the durability and energy performance of the homes we built.
When the subject turns to advanced framing, most builders think immediately of two foot on center 2 x 6 framing and California (3 stud) corners. While these are two of the time proven and widely accepted advanced framing practices, they are only a couple of examples of possible savings. Other resource efficient components have been accepted into common practice with hardly a second thought. Roof trusses, from the simple to the very complex, dominate today's construction market. Floor trusses and floor systems using composite joist and decking materials have also captured major market shares. The use of composite framing members, particularly in headers and tall wall assemblies, is increasing as well. As shown in the framing illustration, all of these components can be efficiently combined in "stack framing" where the designed load path is continuously aligned from the foundation through the wall systems to the roof trusses. This engineered approach allows for much more efficient and cost effective use of lumber. A few builders have adopted the practice of using only a single top plate when stack framing. More are shifting to the use of single top plates on all interior, non-bearing walls. Some are using 24 inch on center floor truss spacing with a thicker sub-floor while others are more comfortable using 19.2 inch floor truss spacing or staying with the traditional 16 inch spacing. Their decisions are driven by what choice works best for them. Other factors in these decisions are the availability of materials and familiarity with different advanced framing styles.
Building America (DOE) photo
An easy change to make is the incorporation of headers into the floor or roof system above windows. Because the floor or ceiling joist is already in place, some material savings can be realized. The opportunity to move these large thermal bypasses up into a floor or roof system and increase the amount of insulation in the walls over windows is another advantage gained that can impact comfort and thermal performance. In the photo showing floor framing, you can see that the band joist has been doubled to provide the header for the window below.
Other options are also available to increase resource and energy efficiency by reducing materials or changing framing style. While reducing the amount of lumber used to frame homes can result in savings, any changes considered should always be evaluated at the very earliest design stage and through the entire process to assure that all structural requirements are met and codes are satisfied. The old maxim for the most efficient use of time and other resources still holds true today. First, plan your work: Then work your plan.
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