Tech Solutions 536.0 WEATHERMATE Straight Flashing Commercial Installation Guide
Table of Contents Product Overview.................................................................................3 Benefits of Detailed Window Flashing.................................................................3 Installation on Flat Surfaces.........................................................................4 Outside Corner Flashing............................................................................5 Inside Corner Flashing..............................................................................6 Fenestration Flashing Recommendations.............................................................7-9 Wall Penetrations..............................................................................10-11 Common Installation Errors......................................................................12-13 Flashing Details...............................................................................14-15 2
Product Overview This document describes how to use WEATHERMATE Flashing Tape to create an air and weather barrier layer by sealing the insulation board joints and through wall penetrations in a wall assembly. This applies only to tested Dow wall assemblies that include THERMAX and/or STYROFOAM Extruded Polystyrene Foam Insulation products. For more information on the THERMAX Wall System, visit www.thermaxwallsystem.com. For more information on Ultra Air Barrier Wall System visit www.ultrawallsystem.com. WEATHERMATE Straight Flashing combines a tough plastic film facer with a 20 mil butyl rubber adhesive that offers a strong bond to foam, most sheathing facers, wood, metal and masonry and concrete. A polymeric-coated paper release liner on the flashing offers easy application. WEATHERMATE Straight Flashing should be installed on clean, dry, frost-free surfaces. Before application, surfaces should be cleaned to remove moisture, dirt, dust, grease/oils and other contaminants that may limit adhesion. Remove sharp protrusions in surfaces to avoid punctures in the flashing. When installing the WEATHERMATE Straight Flashing on substrates where the adhesion may not be optimum, apply a spray adhesive such as 3M High Strength 90 on the substrate before application. Minimum application temperature for WEATHERMATE Straight Flashing is 25 F (-4 C). WEATHERMATE Straight Flashing should not be stretched or pulled as it is applied. This can cause wrinkles and can also result in the facer shrinking back to its original length which will expose some adhesive on the ends of the tape. WEATHERMATE Straight Flashing may be left exposed to sunlight for up to 180 days before covering with the exterior cladding. A general installation guide for WEATHERMATE Flashing Tape cannot cover every possible scenario in which it would be used to seal the wall system against air and water penetration. In all cases, flashing tape should be thought of as a bridge to seal the gaps between insulation boards or between insulation boards and a penetration such as a door or window. If a question arises on how to seal a given penetration, consider using the flashing tape to create a continuous waterproof line of defense from the sheathing to the waterproof portion of the penetrating element. This line can also include liquid sealants such as polyurethane or silicone. Always wear personal protective equipment, including gloves and safety glasses, and use safe work habits during building and construction projects. For more information on WEATHERMATE Flashing Tape visit www.ultrawallsystem.com Benefits of Detailed Window Flashing Proper window flashing is critical because it diverts water that may get behind the exterior cladding to the exterior of the building. Water tightness of the windows is critical in ensuring full performance of the building envelope. The window flashing is also part of the air barrier system that reduces air leakage into the building. Improper installation and faulty design details for flashing can result in water leakage, mold, warping, and eventually structural damage requiring costly repairs. 3
Installation on Flat Surfaces To install the WEATHERMATE Straight Flashing, cut the material into pieces (approximately 5' in length) that can be easily applied in a straight and true manner to maintain coverage and overlaps without wrinkles. Flashing may be cut with a utility knife or cutting shears. Use safe cutting practices and wear protective equipment including gloves. Peel back the release paper from the butyl backing about 12 inches and position the material so that it is aligned in the direction and location in which it will be placed. If this is on an insulation board joint, it should be parallel to the joint that you want to seal and lapped equally on both sides of the joint (See Image 1). Press the first inch of the material onto the substrate to secure the material in place (See Image 2). Keeping the strip in place, peel back the release paper and press/smooth the flashing into place moving along the joint. Proper adherence of the flashing to the substrate is best achieved by working the adhesive onto the substrate using a smoothing tool like a roller or a flat piece of plastic to ensure a complete seal and strong bond. Smooth out all air bubbles and wrinkles (See Image 3). Flashing should always be lapped in a water shedding (ship-lapped or shingle) fashion starting from the lowest point. This means that you start from the bottom of the wall and work your way up. By having the top piece of flashing placed over the bottom piece, you will help shed the water as it drains down the face of the materials serving the function as a water resistive barrier (See Image 4). Image 1 Image 2 Roller Smoothing Tool Flat Plastic Smoothing Tool Image 3 Image 4 4
Outside Corner Flashing Select the width of WEATHERMATE Straight Flashing that will cover at least 2 of the sheathing at each side of the corner plus the exposed butt end of the insulation. Starting from the bottom working up in water shedding shingle fashion, apply WEATHERMATE Straight Flashing first to one side of the external corner. Make sure that this is fully applied and worked into the surface of the insulation along the entire length of the piece of flashing tape. Then fold over and adhere to the adjoining sheathing surface covering a minimum of 2 of the sheathings surface (See Images 5a and 5b). Image 5a Image 5b Flashing lap joints should be a minimum of the width of the flashing. Be sure to firmly smooth over the underlying flashing to eliminate the potential bridge gaps and channels. For example, If you are using 4 inch (100 mm) wide material, then install the material with a 4 inch (100 mm) overlap and when using a 6 inch (150 mm) wide material, then install the material with a 6 inch (150 mm) overlap (See Image 6). Image 6 5
Inside Corner Flashing Starting from the bottom working up in water shedding shingle fashion, apply a vertical piece of WEATHERMATE Straight Flashing first to one side of the internal corner. This is a more difficult installation than an external corner because the second half of the flashing must be kept from prematurely adhering to the second insulation surface avoiding an unadhered bridge across the corner seam (See Image 6a). Make sure that the first side is fully applied and worked into the surface of the insulation along the entire length of the piece of flashing tape. Use a smoothing tool to ensure that the flashing is installed all the way into the corner (See Image 6b and 6c). Then fold over and adhere to the adjoining sheathing surface covering a minimum of 2" (+/- 1/2" tolerance) of that sheathing s surface. A plan view of installing vertical WEATHERMATE Straight Flashing on an inside corner. Incorrect Correct Image 6a Image 6b Image 6c Always terminate the horizontal flashing at all corners, specially inside corners (See Image 7a). Start a new piece of flashing tape on the adjacent side of the corner. DO NOT bridge the corner as this can result in the flashing slightly pulling away from the insulation substrate which would compromise the water barrier qualities of the system (See Image 7b). Image 7a Image 7b 6
Fenestration Flashing Recommendations Non-Flanged Block Frame Step 1. Prepare opening and ensure surfaces are clean, dry and smooth. Select the flashing width that will cover a minimum of 2" (+/- 1/2" tolerance) of the structural wall, plus sheathing thickness, plus an additional 2" minimum (+/- 1/2" tolerance) overlap on the sheathing surface. Note: You will need to use 6" wide flashing tape for almost all situations, or even 9" wide flashing tape if the sheathing is more than two inches thick. Step 2. Cut two flashing strips 12" long and apply them into each of the opening lower corners so that a minimum of 2" (+/- 1/2" tolerance) of flashing can overlap the sheathing and a minimum of 2" (+/- 1/2" tolerance) can overlap on to the structural wall. Make sure to work the flashing onto the surface of the structural wall. When applying the flashing tape into the corner of the window, do not allow the flashing to bridge the corner, creating an air gap and a weak point in the flashing. Instead, work the flashing completely into the corner from one side with a plastic smoothing tool. Only after the flashing is seated firmly in the very edge of the corner should the remaining flap of flashing be applied onto the remaining face of the corner (See Image 8). Image 8 Step 3. Make two relief cuts near the corner of the installed flashing tape (Image 8a). Carefully fold the long sides of the flashing tape resulting from the cuts onto the sheathing surface (Image 8b). Then fold the corner tab created by the cuts onto the sheathing surface (Image 8c). Work the flashing tape onto the sheathing surface (Image 8d). Image 8a Image 8b Image 8c Image 8d 7
Fenestration Flashing Recommendations (continued) Step 4. Cut a flashing strip the width of the opening plus 2 widths of the flashing. Center the flashing piece horizontally across the bottom of the opening and apply to the wall so that a minimum of 2" (+/- 1/2" tolerance) will cover the sheathing below the opening. After this piece is installed and worked onto the insulation, cut the flashing at each side of the opening. Fold the resulting flap down onto the insulation and structural wall of the opening taking care to make sure there are no folds or bubbles. This flap must extend at least two inches onto the structural wall (See Images 9a, 9b and 9c). Image 9a Image 9b Image 9c Step 5. Apply jamb flashing to the side of the opening. This procedure is very similar to Step 4. Cut two flashing strips the height of the opening plus 2 widths of the flashing. Starting with one side, center vertically and apply to the wall so that a minimum of 2" (+/- 1/2" tolerance) will cover the sheathing along each jamb in the opening. After this piece is installed and worked onto the insulation, cut the flashing at each side of the opening. Fold the resulting flap down onto the insulation and structural wall of the opening taking care to make sure there is no fold or bubbles. This flap must extend at least 2 onto the structural wall. Repeat on the other side of the opening (See Images 10a, 10b, 10c and 10d). Image 10a Image 10b Image 10c Image 10d 8
Fenestration Flashing Recommendations (continued) Step 6. Apply header flashing. This is done is a manner identical to the base and jamb flashings described in the previous steps. Cut a flashing strip the width of the opening plus 2 widths of the flashing. Center horizontally and apply to the header so that a minimum of 2" (+/- 1/2" tolerance) will cover the sheathing above the opening. After this piece is installed and worked onto the insulation, cut the flashing at each side of the opening. Fold the resulting flap onto the insulation and structural wall of the opening taking care to make sure there is no fold or bubbles. This flap must extend at least 2 onto the structural wall. Step 7. Install fenestration per manufacturers guidelines. Step 8. Seal fenestration exterior perimeter per fenestration manufacturers recommendations. A high quality construction sealant which is designed to adhere to smooth surfaces should be used. DOW CORNING 758 SILICONE WEATHER BARRIER SEALANT is an example of a product designed for adhering to low energy or slippery surfaces common in sheet or peel and stick weather resistant barriers. Step 9. Seal any gap between the window frame and the structural wall with an approved sealant. Seal void spaces on the interior side around the window using GREAT STUFF PRO Window & Door Insulating Foam Sealant** (See Image 11). Image 11 9
Wall Penetrations Penetrations through the wall system, such as ducts or pipes, also need to be sealed to maintain the weather barrier integrity across the entire envelope. Square Penetrations Install strips of flashing on all four sides, starting at the bottom, then down the sides and finish by installing a strip along the top. The strips of WEATHERMATE Flashing shall be positioned so that the flashing overlaps the THERMAX (ci) Exterior Insulation by 2 (+/- 1/2" tolerance) (50 mm) and the penetration by 2 (+/- 1/2" tolerance) (50 mm). Install the bottom strip by folding it in half along the long dimension, and pressing one half of the strip against the sheathing. Use a smoothing tool to get the tape pressed into place all the way into the corner. Then fold the other half against the penetration (See Image 13). Image 13 Cut the flashing tape along the edge of the penetration and fold the resulting flap back against the sheathing and smooth into place (See Image 14). Image 14 Follow this same procedure for each side of the penetration making sure to work the flashing into the very corner of the penetration prior to folding over the flap of flashing tape (See Image 15). Repeat this procedure for the top of the penetration to complete the flashing process. Image 15 Note: If the gap between the duct and the opening is over 1, fill the space between the duct and the opening with foam sealant (either GREAT STUFF Big Gap Filler Insulating Foam Sealant** or FROTH-PAK Foam Sealant**). After the foam sealant has fully set, trim the excess foam flush with the opening per manufacturer s recommendations and apply the WEATHERMATE Flashing tape as outlined above. Choose the width of the flashing tape to ensure the flashing tape extends at least 2 onto the duct and 2 onto the wall sheathing. **Consult label and Material Safety Data Sheet carefully before use. 10
Round Penetrations Round penetrations are flashed with a slightly different method than those described above. Step 1. Seal the space between the penetration and the wall using a single component foam sealant such as GREAT STUFF PRO Insulating Foam Sealant.** Trim off any excess per installation instructions (See image 16). Image 16 Step 2. Apply either WEATHERMATE Straight Flashing Tape or Flexible Flashing Tape to complete the sealing process. When using WEATHERMATE Straight Flashing Tape, cut a piece of 9 inch wide tape the same length as the circumference of the penetration. Along one side of the flashing, make cuts in the flashing spaced 1 (25 mm) apart. Install flashing against the THERMAX (ci) Exterior Insulation with one edge up against the penetration. As you do this, the flashing will fan out as it curves around the penetration. Cover the spaces between the splayed out flashing with additional pieces of straight flashing applied shingle style around the opening (See Image 17). Image 17 When using WEATHERMATE Flexible Flashing Tape, wrap two pieces of flashing tape around the bottom and then the top of the penetration. Wrap the inner portion of the flashing onto the penetrating object itself (See Image 18). Image 18 **Consult label and Material Safety Data Sheet carefully before use. 11
Common Installation Errors Flashing Application (Do s and Don ts) Example 1 - Applying Flashing Tape to Inside Corners What TO DO: When possible, cut flashing pieces in no longer than 4 foot sections Press the flashing into one side of the corner first - adhering it completely on one side and pushing it as far as possible into the corner. Then press the remaining side onto the adjacent surface. Be careful to press tightly in the corner and avoid bridging the angle In areas where a vertical seal can be applied, always apply the vertical piece first (less potential for shrinkage and bridging with a vertical piece). The horizontal piece can be cut at the intersection and sealed to the vertical flashing face What NOT to do: Do NOT apply from right to left and across the angle. Do NOT over stretch the flashing tape (this can result in poor adhesion and bridging effect) This applies to inside and outside corners Example 2 Stretching of tape What TO DO: Smooth the tape so it adheres properly to the substrate Make sure the edges of the tape are properly adhered What NOT to do: Do NOT stretch the tape stretching results in wrinkles, lack of adhesion to substrate, and tape facer shrinking back to its original dimension, exposing the butyl adhesive on some edges CORRECT INCORRECT 12
Example 3 Loose Edges & non coverage over caps What TO DO: ALWAYS press out the flashing piece ensuring entire surface area is adhered to insulation facer In areas where there are non flush materials such as fastener caps, ensure that you have a minimum of 1 overlap of tape on the joint and fastener cap Default to a wider flashing tape if overlap cannot be achieved Smooth the tape so it adheres properly to the substrate What NOT to do: Do NOT leave edges of tape unadhered. This can lead to water intrusion into the wall system Do NOT flash over items without providing the proper amount of overlap. In the example above, the fastener cap is not completely covered, allowing for a gap to be formed for water intrusion Do NOT stretch the tape stretching results in wrinkles, lack of adhesion to substrate, and tape facer shrinking back to its original dimension, exposing the butyl adhesive on some edges Example 4 External Strapping What TO DO: Always apply good building science techniques and effect to provide proper water drainage properties What NOT to do: Do NOT apply flashings over top of other wall components when it can be avoided Example 5 Common Sense Do NOT apply flashings over top of uneven surfaces Do NOT apply flashing over top of materials such as caulking, spray foam and foam sealants without trimming the material to ensure proper adhesion and water drainage properties Do NOT install the tape on a wet or dusty surface this results in improper adhesion of the tape to the substrate. 13
Flashing Details The detail in the figure above has been tested to verify installation with the THERMAX Wall System based on stringent external water evaluations through the Testing Method -ASTM E547 Standard Test method for Water Penetration of Exterior Windows, Skylights, Doors and Curtain Walls and E331, at the National Certified Testing Laboratory 14
This detail is also recommended to be used with the THERMAX Wall System, but it has not been externally tested. 15
For Technical Information: 1-866-583-BLUE (2583). For Sales Information: 1-800-232-2436 THE DOW CHEMICAL COMPANY. Dow Building Solutions. 200 Larkin. Midland, MI 48674 www.dowbuildingsolutions.com Illustrations are not intended to replace the need for design by appropriate professionals such as architects or engineers. NOTICE: No freedom from infringement of any patent owned by Dow or others is to be inferred. Because use conditions and applicable laws may differ from one location to another and may change with time, Customer is responsible for determining whether products and the information in this document are appropriate for Customer's use and for ensuring that Customer's workplace and disposal practices are in compliance with applicable laws and other government enactments. The product shown in this literature may not be available for sale and/or available in all geographies where Dow is represented. The claims made may not have been approved for use in all countries. Dow assumes no obligation or liability for the information in this document. References to Dow or the Company mean the Dow legal entity selling the products to Customer unless otherwise expressly noted. NO WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED. STYROFOAM Brand Extruded Polystyrene Foam Insulation CAUTION: This product is combustible. Protect from high heat sources. A protective barrier or thermal barrier may be required as specified in the appropriate building code. For more information, consult MSDS, call Dow at 1-866-583-BLUE (2583) or contact your local building inspector. In an emergency, call 1-989-636-4400. Dow Polyisocyanurate Insulation CAUTION: This product is combustible and shall only be used as specified by the local building code with respect to flame spread classification and to the use of a suitable thermal barrier. For more information, consult MSDS, call Dow at 1-866-583-BLUE (2583) or contact your local building inspector. In an emergency, call 1-989-636-4400. GREAT STUFF PRO Insulating Foam Sealant products contain isocyanate and a flammable blowing agent. Read the label and Material Safety Data Sheet carefully before use. Eliminate all sources of ignition before use. Wear long sleeves, gloves, and safety glasses or goggles. Provide adequate ventilation or wear proper respiratory protection. Contents under pressure. FROTH-PAK Spray Polyurethane Foam contains isocyanate, hydrofluorocarbon blowing agent and polyol. Read the instructions and Material Safety Data Sheets carefully before use. Wear protective clothing (including long sleeves), gloves, goggles or safety glasses, and proper respiratory protection. Do not breathe vapor or mist. Use only with adequate ventilation. It is recommended that applicators and those working in the spray area wear respiratory protection. Increased ventilation significantly reduces the potential for isocyanate exposure, however, supplied air or an approved air-purifying respirator equipped with an organic vapor sorbent and a particulate filter may still be required to maintain exposure levels below ACGIH, OSHA, WEEL or other applicable limits. For situations where the atmospheric levels may exceed the level for which an air-purifying respirator is effective, use a positive-pressure, air-supplying respirator (air line or selfcontained breathing apparatus). Spraying large amounts of foam indoors may require the use of a positive pressure, air-supplying respirator. Contents under pressure. WARNING: Rigid foam insulation does not constitute a working walkable surface or qualify as a fall protection product. Building and/or construction practices unrelated to building materials could greatly affect moisture and the potential for mold formation. No material supplier including Dow can give assurance that mold will not develop in any specific system. Dow Polyurethane Foam Insulation and Sealants CAUTION: When cured, these products are combustible and will burn if exposed to open flame or sparks from high-energy sources. Do not expose to temperatures above 240ºF (116ºC). For more information, consult MSDS, call Dow at 1-866-583-BLUE (2583) or contact your local building inspector. In an emergency, call 1-989-636-4400 in the U.S. or 1-519-339-3711 in Canada. Printed in U.S.A. Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Form No. 179-04147-0613MCK 178-04038-0613MCK McKAY216510