Designing an Air Barrier Specification
Following is a list of general questions that will help us to design an air barrier and/or foam insulation specification for your firm. Please feel free to call me if any of the questions require further clarification. More specific questions may follow as we refine the specification to meet the needs of your firm or project.
- Do you want this specification to be written for average (typical) performance, high-performance, or state-of-the-art performance buildings?
- Do you want a universal specification that works for nearly every building (exceptions would be special environments such as pools, saunas, greenhouses, cold storage, etc.), or a specification with specifier notes that allow the specification to be customized for each job?
- Who do you want to make responsible for the air barrier- the Owner, the General Contractor, or a Sub-contractor?
- Do you want all of the components, quality assurance requirements, and warranties related to the air barrier system to be on one separate section or scattered throughout the specifications in the usual locations? (i.e., Vapor and damproofing, insulation, sealants, masonry, Division 1, etc.)
- Do you want testing to be part of the air barrier specification? What kind of testing: Quality assurance testing, compliance testing?
- Do you want to set a numeric airtightness standard for your buildings? (Typically reported in cubic feet of air flow per minute per square foot of envelope surface area at a pressure difference of 50 Pascals {CFM50/sq. ft.}). For example: the US ACE has a standard for all of its buildings (.19 CFM50/sq. ft.), some states have a standard, and designers who want to reduce construction costs by taking advantage of reduced air leakage rates set standards for their projects.
- Does the specification need to comply with a specific code or certification? For example: a State’s energy code, IBC, LEED certification, or ABBA certification.
- Are there specific alternates that you would like added to the specification?
- Are there specific submittals or Installer certifications required?
- Are there specific warranties or bonds you would like to have in the specification related to air barrier performance?
- Do you want a specific allowance for testing?
- Are there specific building materials pertaining to the A/V barrier that you would like listed in this specification? Do you want to specify a specific product (proprietary), a set of prescriptive products, or a performance standard for any product on the market?
- How do you want the results of the individual tests reported? Who do you want to make responsible for the testing? Who will be responsible for masking and isolating test areas, the GC or the testing agency. Who will be responsible if the compliance test fails? Who will be responsible if there is dispute over the test result (pass or fail)?
- In what units do you want the performance of the air barrier reported?
Specification Methods
Bill Rose: “There is nothing in the AIA Code of Ethics that says anything about performance.”
Writing criteria for product and system performance is very transparent. Everyone knows what the product and installation goals are. Specifying a product or class of products doesn’t communicate the performance intent of the design. The physical properties and performance details are hidden in the manufacturer’s data. There is no way to easily know when cookie-cutter Proprietary and Prescriptive Standards/Specifications become obsolete and no way to easily make adjustments to these specifications to keep them up to date.
| Does this specification method guarantee that the: | Proprietary | Prescriptive | Performance |
| Specified BE Performance will be achieved |
No* |
No |
Yes |
| Energy use will be lower |
No |
No |
Yes |
| Architect is protected from performance responsibility |
No |
No |
Yes |
| Cost of the design is lower |
Yes |
No |
Yes |
| Cost of the installation is lower |
No |
No |
Yes |
| Standard is simple to write and still protects the parties |
No |
No |
Yes |
| QA protocols are required during construction |
No |
No |
Yes |
| Playing field is level for the bidders |
No |
No |
Yes |
| Use of new, better, lower cost products is allowed |
No |
No |
Yes |
| Specifications are easy to standardize |
Yes |
Yes |
Yes |
| Standardized specifications are easy to keep current |
No |
No |
Yes |
| Physical properties of a product, with respect to compliance for a given application, are easy to evaluate |
No |
No |
Yes |
| Building science implications of a product, with respect to its appropriateness for a given application, are easy to evaluate |
No |
No |
Yes |
| Specification method protects the Architect when specific assembly details are missing |
No |
No |
Yes |
| Specification method requires durability for an installed assembly, not just for the material.*Sometimes these answers are “maybe,” but in general given the choice of yes or no, respond according to which is the most appropriate. |
No |
No |
Yes |