Standard Practice for the Installation of Windows with Integral Mounting Fin in Wood Frame Construction for Heavy Weather and Extreme Window Locations
Introduction: During the hurricane season of 2004 – 2005, the southeast United States received significant water damage through fenestration. The Florida building code commission has asked the Fenestration Manufacturers Association of Florida to create standards that would improve the current installation methods. This document was created by the Fenestration Manufacturers Association, and is now offered to ASTM to establish a consensus process.
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1. Scope
1.1 This standard covers the installation of windows in buildings of no more than 3 stories in height.
1.2 This practice applies windows which employ an integral mounting flange that is permanently attached and sealed to the window perimeter frame and is designed as an installation fastening appendage.
Note 1: The use of a frontal-flanged frame as required for masonry installation is not allowed to be used in wood frame construction, as described by this standard.
1.3 This standard covers the installation process for windows from pre- to post-installation. It does not include fabrication techniques that would be required to join individual windows to each other, either horizontally or vertically. It does not cover any other factory fabrication which joins or combines multiple windows to create bays or combination windows. The instructions for mulling windows together and any accessories required must be supplied by the window manufacturer.
1.4 This standard provides minimum requirements for window installation, illustrating an effective, watertight manner based on state-of-the-art techniques. Actual conditions in buildings may vary. In some cases the window manufacturer will have to be consulted if the field or building conditions are other than as described in this standard.
1.5 This standard does not address safety concerns, either from the installation process or present at the building site. It is the responsibility of the user of this standard to ensure that all appropriate health and safety practices have been implemented.
1.6 This standard’s techniques have been developed specifically to allow incidental liquid water entering from superficial cracks, either in the cladding or building or window joinery or installation joints, to drain onto the drainage plane, and to exit to the building exterior through a screed.
2. Standard References
2.1. AAMA 711 Voluntary Specification for Self-Adhering Flashing Used for Installation of Exterior Wall Fenestration Products
2.2 AAMA 800 Voluntary Specifications and Test Methods for Sealants
2.3 ASTM C755 Practice for Selection of Vapor Barriers for Thermal Insulation
2.4 ASTM E2112 Standard Practice for Installation of Exterior Windows, Doors and Skylights.
2.5 ASTM E 631 Standard Terminology of Building Constructions
2.6 ICBO Evaluation Service: Acceptance Criteria for Flashing Materials (AC148)
2.7 ICBO Evaluation Service: Acceptance Criteria for Weather-Resistive Barriers (AC38)
3. Definitions
3.1 Back dam, n. Portion of sill pan construction which is the rear upturned leg. This leg can be created from a variety of materials, provided that the height of the back dam is at least 6 mm (1/2-inch) and it is sealed to the pan and to the end dams.
3.2. Building paper, n—a membrane material made of cellulose paper impregnated with asphalt (to inhibit passage of liquid water through the material) and which is commonly used as a concealed weather-resistive barrier in membrane/drainage walls.
3.3 Compatible Materials – Materials that can exist in close proximity to one another without detrimental effect.
3.4 End dam, n. Portion of sill pan construction which is the side upturned leg. This leg can be created from a variety of materials, provided that the height of the end dam is at least 62 mm (2-1/2-inch) higher than the sill pan surface and it is sealed to the pan and to the back dam, to cause a 3-sided water-capturing pan.
3.5 Flange-mounted, a.k.a. frontal-flanged, adj.—refers to a type of window which has a flange projecting parallel to the plane of the wall, located at the most exterior surface of the window for the purpose of installing the window against a backstop, buck, receptor, groove, or other such stepped features that are incorporated into the rough opening to act as a backstop for the flange only, to seat a window into a masonry opening.
3.6 Flashing, n—sheet material integrated with the weather-resistive barrier that bridges and protects the joint (gap) between the window or door frame members and the adjacent construction for the purpose of preventing water penetration by draining water away from the window or door. See Mechanically attached flashing, Self Adhering flashing, Pan flashing.
3.7 House wrap, n—a polymer-based sheet material provided in a variety of dimensions and used as a water-resistive barrier (User of this product should defer to manufacturer's instructions).
3.8 Mechanically attached flashing - any durable material with low or no permeance that is designed to prevent liquid water from passing through it. When mechanically attached flashing is used, a dimension of not less than 9 inches is required.
3.9 Mounting fin, a.k.a. integral fin, n—a permanent appendage protruding from the body of a window or door, used as either an installation attachment feature or part of the water-resistive barrier interface between the product and the wall, or both. The term “fin” is also known as “flange”. A fin projecting from the frame of the window, parallel to the plane of the wall, for the purpose of securing the window to the building structure.
3.10 Pan flashing, a.k.a. sill pan, n—a type of flashing used at the base of rough opening to divert water to the exterior or to the exterior surface of a concealed WRB. Pan flashings have upturned legs at the rear interior edge (back dam) and right and left sides (end dams), to form a three-sided pan that has the front open for drainage. They are intended to collect and drain water toward the exterior, including water that may enter through the window unit or around the window (between the rough opening and the fenestration). The pan flashing must be integrated with other flashings and the window assembly to capture water that may otherwise penetrate to the sill framing and allow it to freely drain to the exterior. The window, flashings and pan must be sealed in a manner that reliably inhibits air and moisture flow to the interior.
3.11 Residential building, n - A building of no more than 3 stories, which can be single or multi-unit, usually developed for the purpose of a residence.
3.12 Self Adhering Flashing – Flexible facing materials coated completely or partially on at least one side with an adhesive material and which do not depend on mechanical fasteners for permanent attachment.
3.13 Shim, n - a thin, flat or wedge-shaped piece of wood or other suitable material used to level or plumb a fenestration product frame during installation.
3.14 Water-Resistive Barrier (WRB), n - the surface or surfaces of a wall system which complies to ICC AC38 is responsible for preventing water infiltration to the building interior. A membrane, also called a housewrap, whose primary function is to act as a drainage plane for liquid water, which has a permeance high enough to keep liquid water from penetrating through the surface.
3.15 Weep Screed, n. A permanent member with gaps designed to allow liquid water to exit from the drainage plane to the exterior of a building; located at the bottom of wall claddings between the drainage plane and the cladding.
4. Significance and Use
4.1This practice recognizes that the effective performance of installed fenestration products is dependent in part upon following proper installation procedures and appropriate workmanship.
4.2This practice recognizes that the coordination of trades and proper sequencing are essential for effective fenestration installation. The general contractor shall be responsible for the necessary coordination of trades and proper construction sequencing of the installed fenestration product.
4.3Improper installation of units contributes to excessive air, water and sound leakage, and condensation. It may promote the deterioration of wall constructions, insulation, fenestration products, and their respective finishes.
4.4This practice presumes a working knowledge of applicable federal, state, and local codes and regulations; specifically, but not limited to required means of egress, requirements for safety glazing materials, and structural requirements of applicable codes.
4.5This practice presumes a working knowledge of the tools, equipment, and methods necessary for the installation of specified fenestration products. It further assumes familiarity with flashing and sealing, glazing procedures, finishes where applicable, and an understanding of the fundamentals of construction that affect the installation of these units.
4.6This practice presumes that the products that have been furnished for the installation and their locations within the structure comply with all the applicable building codes and regulations.
4.7 This standard recognizes that the installer must have a working knowledge and an understanding of the fundamentals of the methods necessary for the installation and application of caulking, sealants, and coatings as required for the installation of the window, including their compatibility with other products.
5. Related Issues and Procedures
5.1Continuity— Continuity shall be maintained between all elements in the fenestration product and the surrounding wall. Where the installer is required to furnish or repair a vapor barrier, the material shall comply with the requirements of ASTM Practice C755.
5.2Joints and Anchorages—Joints and anchorages between the building envelope (water-resistive barrier assembly) and fenestration product shall be designed to accommodate differential thermal expansion within the window/wall assembly.
5.3Construction Sequence—Effective integration and continuity of the fenestration product and other components of the building envelope is dependent on proper construction sequencing.
5.4Construction Damage—The installed water-resistive barrier shall be protected from damage during construction. Any damage to the water-resistive barrier shall be repaired prior to completing the installation of the fenestration product.
5.5 Pre-Installation Requirements performed by others, per manufacturers instructions.
5.5.1 Rough Openings
5.5.1.1 The builder shall construct the rough openings in accordance to the window manufacturer’s size and tolerance requirements.
5.5.1.2 The rough opening shall be square, plumb, and level prior to the installation of the window. Rough openings diagonal dimension must be square; no more than a 6 mm (1/4-inch) tolerance diagonally will be allowed. Horizontal and vertical dimensions of the rough opening can be no smaller than described above and up to 3 mm (1/8-inch) larger. Manufacturer’s instructions may supersede these tolerance ranges.
5.5.2 Water-Resistive Barriers (WRB) – The installation of the WRB will vary from the sequence of window installation. Method A1 or method B may be used depending on the sequence of construction. Prior to installation, the wood frame structure will have been covered completely with one layer of WRB, covering 100% of the vertical surfaces of the wall, lapped, fastened, taped, and sealed per the WRB manufacturer’s instructions. Penetrations through the WRB for the installation of windows will be made pursuant to this standard by the window installer. Where a water-resistive barrier (WRB) is used, apply the WRB in water shedding fashion, starting at the base of the wall and working towards the top. Install the water-resistive barrier to the face of the building framing or sheathing flush with the rough opening of the window head, jambs and sill.
5.5.3 Sealants – All gunnable sealants shall comply with ASTM C 920 Class 25 or greater for proper joint expansion and contraction. In addition, the sealant shall be chemically curing to minimize cracking, loss of adhesion and shrinkage. Solvent and waterborne products such as latex, acrylic, other water and solvent based tri-polymer blend products shall not be used due to the high shrinkage and low joint movement for the installation of windows. If preformed tapes are used they must meet ASTM C1281 specification. Prior to using the sealants seek input from sealant manufacturer for proper joint design and sealant selection.
5.5.4 Cladding - Prior to window installation, no claddings shall be installed.
5.5.5 Related Procedures – Post-Installation by others
5.5.6 Second Layer WRB
5.5.6.1 A second layer of WRB or building paper (BP) in accordance to state and local code may be required. After the window has been fully installed and sealed to the water-resistive barrier (WRB) per this standard, a second WRB or BP will be installed on top of the first layer. This material will be either one layer of WRB or BP (Kraft/building/stucco paper/felt) per code and manufacturer’s instructions. The second layer will be installed over the complete surface of the wall, and will not be interfaced with the windows. No attempt will be made to seal this second layer to any part of the first layer of WRB. This second layer of WRB or BP will be lapped, fastened, and taped, per the WRB or BP manufacturer’s instructions; but not sealed to the building.
5.5.6.2 After the installation of the second layer of WRB, the cladding will be applied with a screed installed at the bottom of the first floor and in between all floors above; one per story.
6. Window Installation Procedures
6.1 Pre-Installation Inspection
6.1.1 Before installation can occur, the installer will inspect the WRB for tears, penetrations, or defects within 300 mm (12 inches) past the rough opening area. Any tears, penetrations, or punctures will be sealed per the WRB manufacturer’s instructions before the installation starts. Refer to ASTM C755.
6.1.2 Verify that the rough opening is square, plumb, and true. Notify contractor to remedy any discrepancies per this standard.
6.1.3 Verify the WRB Housewrap is installed in accordance to this standard and the WRB Manufacturer’s instruction.
6.2 Installation Procedures (Method A1 and B)
Note: Two methods of installation are recommended in this procedure, Method A1 and Method B.
6.2.1 Method A1 Installation
6.2.1.1 Cut WRB Housewrap in the rough opening.
6.2.1.2 Step 1: At the head of the opening, starting at the top corner of the window (rough) opening, measure from the corner a dimension equal to the width of the flashing to be applied, over, and mark. At a 45° angle, carefully cut the WRB on a diagonal. Gently raise the top edge of the WRB up and temporarily tape the top corners and center to the exterior water-resistive barrier surface above. This is done in order to allow for installation of the window and flashing later.