This is still very legitimate since the testing and calculation process is exactly the same. It is worth pointing out that while scientists and engineers like to work and think in fractional U-factors, most of the general population prefers whole numbers, which has made R-values the popular means to talk about thermal capabilities of materials. All thermal energy calculations in building enclosures (i.e., walls, roofs, etc.) are based on this fundamental formula. Applying this to a building, the fundamental formula used is (U x A) x dT where U= the tested U-factor for one square foot of material, A= the area in square feet installed in a construction assembly, and dT is the design or actual temperature difference between indoors and outdoors. The resulting number is generally a decimal (e.g., 0.5), with smaller numbers indicating small amounts of heat transfer (think insulation) and higher numbers indicating more heat transfer (think conductive metal). (The greater the difference in temperature between the two sides of the material, the faster or more intensely that heat flows.) In order to determine how much heat is transferred through any specific material, its U-factor is determined by testing that material on a square-foot basis over time, while measuring the temperature difference between the two sides. The means to measure heat transfer in building products is based on U-factors, which indicate how many British thermal units (BTUs) of energy pass through a defined size of material (i.e., one square foot) over time (specifically one hour) for each degree Fahrenheit in temperature difference. Those tests are grounded in the fundamental laws of physics and thermodynamics that, among other things, point out that heat always seeks a balance by flowing from a warm source to a cooler place. This is quite observable and measurable using standard techniques that test different materials for the amount of heat flow or heat transfer through them. Simply put, the framing allows more heat to flow through it than insulation does. Why Continuous Insulation?įramed wall construction, whether using wood studs or metal studs, has an inherent weakness from a thermal efficiency point of view. With new integrated sheathing, this layer is built in to the back of the nailable sheathing that goes directly against the framing.
The energy performance of exterior walls is enhanced by including exterior continuous insulation.
#Home designer architectural insulation in studs code#
This course will help provide clarity on the differences between the varied prescriptive code requirements for continuous insulation in different climate zones, along with principles and choices related to proper moisture management.Īll images courtesy of Huber Engineered Woods LLC, except as noted All of these variables and options have led to some significant confusion concerning the best way to properly address both code-required exterior thermal insulation and vapor management in wall assemblies. There is also concern that the continuous insulation can impact the ability of the wall to “breathe” and release any trapped moisture from within the assembly so, in some cases, it can impact the choice of an interior vapor retarder on the warm, inner side of the building. Codes and best practices suggest different amounts of continuous insulation for different climate zones. This is especially true in the case of providing exterior continuous insulation as part of a framed exterior wall. Specifically, determining the best amount and type of insulation to use may be unclear, particularly in light of controlling water vapor or moisture that can become trapped in constructed wall assemblies. While this is a positive trend, there are some notable wall design issues to address. This is achieved in wood-framed buildings by addressing both insulation levels and air tightness. Building codes and green building standards are continuing to raise the bar on energy efficiency and high performance in buildings.
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