SPRAYFOAM Professional - Spring 2016 - (Page 57)

ABAA NEWS AIR LEAKAGE PATHS IN A TYPICAL WOOD FRAMED WALL ASSEMBLY BY LAVERNE DALGLEISH, PRINCIPAL, BUILDING PROFESSIONALS T he Air Barrier Association of America (ABAA) worked with Oak Ridge National Laboratories (ORNL) to conduct assembly testing on a wood framed wall to determine what part of a wall would leak the most. The testing was conducted at Tremco's facility in Cleveland Ohio, where they have a fully automated ASTM E2357 test apparatus. The funding to ORNL was supplied by DOE's Building America Program. This research was an extension to the ABAA Research Project on Air Barriers, which was to determine whether there were energy savings when making a building very air tight. The baseline specimen was a more detailed ASTM E2357 test specimen, where the wall was purposely made very leaky. The specimen was framed in a wooden buck for ease of mounting into the test apparatus. A foundation was simulated with CMU and a wood mud sill was installed with spacers between the mud sill and the CMU to represent normal site conditions. Simulated floor joists with a header were then installed and then a strip of sub floor was installed. The sub-floor was shimmed to replicate the drying and movement of wood framing members on the construction site. A wall was then framed using 2 x 4s with a single bottom plate and a double top plate. The wall was sheeted with OSB. A 1/8 inch gap was maintained between the sheets of OSB which is a standard practice on job sites to allow for the expansion and contraction of the material due to temperature and moisture content. Details on the construction of this wall specimen were documented so that the base specimen could be replicated for additional testing with various types of air barrier materials being installed. To identify how much air would leak through a specific air leakage path, it was decided to test the complete wall specimen to start with and then to seal one crack at a time and test after each air leakage path was sealed. The baseline wall was inserted into the test apparatus and the wall proved to be so leaky, that it was impossible to create a 25 Pa pressure difference across the specimen. This proved the goal of making the baseline specimen very leaky was achieved. Now we talk about a certain air leakage rate at 75 Pa but this is the reported leakage rate. In ASTM E 2357 we actually test up to 600 Pa, then 800 Pa and finally 1200 Pa. You will find that all the testing is conducted at multiple pressure differences and normally much higher than the reported test pressure. The next issue that the crew faced was to find a sealant that would set up in a short period of time so that the testing could be done almost continuously. Normal sealants and caulks require a curing time which would drag out the testing process. Finally an answer was found, which was to use a glue gun. This material set up as soon as it was cooled and provided a structural seal that withstood the loads imposed upon them by the test procedure which created a pressure difference across the wall assembly. To give you an idea of the loads placed on the wall assembly, The other interesting observation was that 92% of the air leakage at the wall/roof intersection was at the joint between the OSB and the top plate." www.sprayfoam.org | SPRAYFOAM PROFESSIONAL 57 http://www.sprayfoam.org

Table of Contents for the Digital Edition of SPRAYFOAM Professional - Spring 2016

EXECUTIVE DIRECTOR’S CORNER
PRESIDENT’S POST
FOAM BUSINESS NEWS
SPFA TODAY
LEGISLATIVE UPDATE
KEYNOTE SPEAKER – RICHARD R. RAWLINGS
OSHA STANDARD FOR CONFINED SPACES:
SUSTAINABLE CONSTRUCTION: TRANSPARENCY AND CHOICE
INDUSTRY’S CHALLENGES SHAPE OUR EVOLUTION
SPF RESEARCH ON AIR QUALITY – PART 2
NEW CONSTRUCTION NEEDS OPEN DOORS FOR SPF INDUSTRY
TOP TRUCKS FOR SPF CONTRACTORS
BEHIND THE FOAM
2015 SPFA CONTRACTOR AWARDS
SPEAKING SENSIBLY
ABAA NEWS
ASK THE EXPERT – How to Write Clear Contracts
UPCOMING EVENTS
INDEX OF ADVERTISERS | ADVERTISERS.COM

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