The Science of Rough Opening Preparation and Window Installation to Minimize Air Leakage

Transcription

1 The Science of Rough Opening Preparation and Window Installation to Minimize Air Leakage Sam Hagerman, Hammer and Hand Florian Speier, Zola Windows Paul Grahovac, PROSOCO, Inc. 1 Abstract Large sums of money are spent on high-performance windows with practically zero air leakage. However, traditional rough opening preparation and window installation methods and materials have been shown not to match the window performance. State-of-the-Art liquid-applied materials and related techniques demonstrate a Passive House level of performance. 2 Background A whole-building repair contractor continuously saw the failings of peel-and-stick membranes and building wraps. Using a Systems Engineering approach, they developed and commercialized a liquid-applied system that not only solves water-damage issues but also dramatically reduces air leakage. Hammer and Hand, a high-quality Passive House builder, has adopted the technology for their projects. Zola Windows also appreciates the need for the highest-quality installation materials and methods. 3 The Session Paul Grahovac will summarize the development of the technology and its technical attributes. Sam Hagerman will describe his company s experience with traditional materials and the reasons they have adopted the new technology. Florian Spier will address high-performance windows and approaches to installation around the country. Florian will give a quick overview of the current availability of high performance windows in the U.S. He will then go over the goals of a high performance installation airtightness, watertightness and a low psi-install, and look at several approaches executed in the last year at Passive Houses projects around the country. He believes there is no single best way to

2 accomplish installation. Mr. Grahovac believes the audience may well conclude the liquidapplied method is preferable. Florian will address install materials costs vs labor costs, and give an overview over achieved air-tightness and thermal performance as calculated in Therm. This overview will give participants the basic tools and knowledge to develop the install details for their projects. The three speakers and technicians from their respective companies will demonstrate the use of the liquid-applied technology in an actual rough opening preparation and window installation. Use of the STPE products. STPE (Silyl terminated poly ether) is the leading sealant in Europe and Asia. First, an STPE joint and seam filling product is gunned out of a cartridge and spread into the joints and seams of the rough opening. Then an STPE liquid flashing coating material is gunned out of a cartridge and spread over the joint and seam material, over the entire inside surface of the rough opening, and 4-6 inches out onto the sheathing wall around the rough opening. The window is set in the rough opening, and backer rod with STPE sealant is used to form an air and water seal around the interior perimeter of the window. At the outside, the STPE liquid flashing material is used to flash over the flanges of the window except for drainage weeps left in the sill area. The rough opening preparation is graphically depicted in the illustration below. Forty-three illustrated installation details for the whole house and an installation video are available at the PROSOCO website 1. A video of Hammer and Hand using the system on the Karuna Passive House is available online 2.

3 Air leakage testing. Below are results of tests performed at the PROSOCO air leakage test chamber facility with window installation mock-ups using 1) sheetwrap with peel-and-stick and 2) the PROSOCO liquid-applied materials. Also below are photos of the 21.25cuft test chamber with the 9sqft liquid-applied mockup along with photos of the large test chamber at PROSOCO. Testing is similar to ASTM E 2357 air barrier assembly testing except with a smaller mock-up. Air Changes per 50 Pascals = 20mph wind Energy Star 5 ACH (Climate Zones 3,4) Passive House 0.6 ACH Sheetwrap 7.01 ACH Liquid applied 0.17 ACH Liquid Applied at 2,880 Pascals = 155mph wind Category V hurricane (water intrusion testing level) 0.53 ACH The results are supported by the recent Karuna project testing where 0.42 ACH was achieved without the air-barrier system fully installed 3.

4 State of the art. Conventional rough opening preparation and window installation follows ASTM E 2112 Standard Practice for Installation of Exterior Windows, Doors and Skylights 4 which does not include methods for utilizing liquid-applied materials. However, Mr. Grahovac is a member of the ASTM E 2112 technical committee, and he has been invited by the Chair of that committee and the ASTM management staff to submit a revision that will add such systems to the ones listed in the standard. The Architectural Record recognized liquid-applied R-GUARD FastFlash in the category of the top waterproofing products of Experts have recognized the shortcomings of materials and methods referenced in ASTM E 2112 that rely on sealing off the face of the rough opening: Notwithstanding the advances in the performance of sealants and membrane materials, reliance upon face sealed systems has a higher risk of water penetration because of the inherent aging of the materials and loads imposed, thus reducing the overall resistance to water penetration and consequent damage....the combination of wood- or steel-framed construction with windows that may leak at some point during their life cycle leads the authors to conclude that only the hot and dry hygrothermal zone may be tolerant of periodic wetting and secondary protection of the window opening is required in all other hygrothermal zones 6. The ENERGY STAR for Homes Version 3 Guidelines 7 provides as follows (emphasis added): Water Management Builder Checklist Section 2. Water-Managed Wall Assembly 2.2. Fully sealed continuous drainage plane behind exterior cladding 2.3. Window and door openings fully flashed Thermal Enclosure Rater Checklist Section 3. Fully-Aligned Air Barriers All exterior walls Section 5. Air sealing 5.2. Cracks in the building envelope fully sealed: Rough opening around windows & exterior doors sealed with caulk or foam The FastFlash system meets these requirements.

5 Designers and builders are moving quickly away from conventional materials (to prepare the rough opening and install the window) to fluid-applied products. They are doing this to avoid water intrusion and air leakage from: Rotting of damp substrates behind vapor barrier coverings Reverse lapping Tenting Tunneling Fishmouths Heat damage Adhesion failures Difficult, laborious work and human error UV damage Installer experience, availability, durability, cost of materials, cost of labor. Physical actions required are pulling the handle on a caulk gun to lay down a bead of material, and spreading it with a piece of flat plastic. Inexperienced workers are successful in their first attempts. Speed and conservation of material increase with experience. Available at hundreds of construction supply distributors across the country. The service temperature of a leading peel and stick membrane is 158 degrees F with a maximum UV exposure of 30 days. These products have been tested to 300 degrees F and may be exposed for up to six months. They do not rip or tear, and any gashes into them can quickly be repaired by re coating. Material suggested retail pricing is $1.30 per lineal foot treated. Labor costs vary based on location and experience. We ve had to add a second shift in the recession to keep up with demand fueled in large part by contractors switching jobs to this system to lower their costs of doing business. 4 References 1. Installation Guidelines illustrations. 77bb 4f48 9f75 ed b Installing the FastFlash System video. eccb 42c3 b940 9d fd f70d d4d b45c _House_cruises_past_060ACH50_threshold_of_Passive_House_and_Minergie P/ construction/ 4. ASTM E 2112 Standard Practice for Installation of Exterior Windows, Doors and Skylights.

6 5. e=3 6. Challenges with Using ASTM E 2112 in North American Climate Zones, Eleventh International Conference on Thermal Performance of Exterior Building Envelopes, sponsored by Building Enclosure Integration Committee of the Building Enclosure Technology & Environmental Council (BETEC) of the National Institute of Building Sciences and ASHRAE, presented at Oak Ridge National Laboratory Building Technologies Research and Integration Center. 7.