|Energy and Thermal Performance This section discusses the thermal performance of the wall and the affects of advanced framing on the total effective thermal resistance of the assembly.
“Advanced Framing” in the EffectiveR Calculator:
Advanced framing is a construction framing system designed to reduce lumber usage and increase energy efficiency. Advanced framing is resource efficient and offers more space for insulation while reducing heat loss through conductive framing members.
Conventional framing, the industry standard for framing residential construction, typically consists of 2×4 (38 x 89mm) or 2×6 (38 x 140mm) wood framing spaced 16 inches (406mm) on center, double top plates, three-stud corners, multiple jack studs, double or triple headers, cripple studs, and other members that are often redundant.
Advanced framing reduces the structural redundancies inherent in conventional framing by placing framing members only where they are needed. The most commonly adopted advanced framing technique is 2×6 (38 x 140mm) wood framing spaced 24 inches (610mm) on center. Other commonly used techniques include single top plates, two-stud corners, single headers or integrated rim headers, minimal use of jack studs and cripples, and the elimination of redundant studs and unnecessary blocking and bridging. Although some advanced framing techniques can be adopted independently, the greatest savings- in both cost of construction and energy- will be realized when the system is applied holistically.
The National Building Code Note A-220.127.116.11.(1) describes advanced framing, and provides framing and cavity percentages in Table A-18.104.22.168.(1)-A. The calculator uses these percentages, which equate to a 4% reduction in framing for stud spacing of 16″ (406mm), 19.2″ (488mm), and 24″ o.c. (610mm).
|Ease of Construction This metric tries to provide a sense of “build ability” in the field. Based on current construction practices, typical scheduling and trade coordination, some wall systems can be built quickly, efficiently, safely with relatively minimal opportunity for mistakes. Other Assemblies may require additional or specialized trades, multiple materials, detailed application processes, and limited material availability. Construction cycle times and production timelines can be affected and additional warranty risks can be introduced.Ease of Construction can also be affected by existing regional building practices. For instance some areas of the country have developed processes enabling quick and efficient integration of exterior continuous insulation on all wall assemblies. The “Ease of Construction” metric is very subjective. None the less, it is intended to “generally” inform the builder of in-the-field construction issues affecting build cycle time and possibly trade selection.
Details addressed in this section may relate to:
|Affordability Implications Affordability is a concern on every project. With this in mind some general commentary is provided with each wall assembly regarding potential cost implications that the builder may encounter when specifying the assembly. These cost considerations are not comprehensive nor do they provide true Life-cycle “costing methodologies. They do however; highlight some various considerations the project estimator may want to include in initial estimates and related takeoffs.|
|Esthetic: Architectural Design A characteristic of every wall assembly is how it appears to the occupant, both from the interior and exterior. The assembly must still be architecturally pleasing, balanced and properly translate the Architects intended theme. With various wall assemblies the designer /Builder may encounter certain challenges with architectural detailing. For instance, thicker walls will often affect elements such as Jamb extensions, depth of glass (window sits deeper into assembly Or is pushed outwards towards the exterior cladding). As various wall sections of the building may require additional structural members (i.e. Tall wall or Zone framing), this will also affect the Effective Thermal value of the wall assembly. High density insulation may need to be specified in these wall cavity areas or additional exterior continuous insulation provided.The commentary in this section is intended to give the designer and builder a heads-up regarding where the most common areas of conflict may occur.|
|Materials Serving More Than One Function Modern building components will, in many instances, serve more than one function within the wall assembly. Polyethylene is the clearest example of a component that acts both as a vapour barrier and when it is properly sealed also as an air barrier. New products that have been designed and tested can serve multiple functions. For instance, some exterior insulating sheathings that are properly sealed can act as insulation but also as air barriers and weather barriers or in the language used by the building code as sheathing membranes that are part of the wall’s second plane of protection.
In some situations, liquid applied water resistive barriers can act as sheathing membranes. In all cases, you should look for an approval by the Canadian Construction Materials Centre or an approval using Division A of the Building Code in force in your location. When in doubt, check with your local building department.
|Additional Sources of information There are unlimited resources at the professional’s finger tips when it comes to sourcing product and assembly information. However, it can often be a challenge to quickly locate reliable, relevant building science and assembly information as it pertains to each individual Canadian Climate zone.
In this section the Designer/Builder Professional can access everything from construction details, scopes of work, relevant and current research and links to approved assembly materials and methods.