TECH SOLUTIONS THERMAX Insulation in Low Humidity Metal Buildings

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1 Summary Low humidity metal buildings are used in the commercial to industrial construction markets and include factories, warehouses, agricultural structures, cold storage structures and similar facilities. Low humidity buildings typically have a relative humidity of less than 50% and may need to maintain constant temperatures that are lower compared to the outside environment. This combination of low humidity and temperature emphasizes the need for good building science in the building design. Using insulation such as THERMAX polyisocyanurate insulation helps safeguard against thermal loss, air leakage, moisture build-up and even fire damage. Model energy codes ASHRAE 90.1 Energy Standard for Buildings Except Low- Rise Residential Buildings and/or International Energy Conservation Code (IECC) - across the country now require continuous insulation (ci) to minimize thermal bridging in certain climate zones to help improve overall thermal performance of the wall. In addition, designers now have to address air leakage by detailing mandatory air barriers. THERMAX Insulation can deliver both continuous insulation and air sealing properties in one easy-to-construct package. Because metal is a very good conductor of heat, installing continuous insulation with a high R-value over the studs minimizes the effect of thermal shorts. With the versatility that designers and installers demand, THERMAX Insulation can be installed in both exterior and interior walls and roofs and over any type of framing: C purlin, Z purlin, wall girts, bar joist or others. Each board of THERMAX Insulation qualifies as an air barrier as per ASTM E By detailing joints and interfaces of THERMAX Insulation with tapes, PVC joint strips, insulation edge treatments, sealants, adhesives and air sealing foams either singly or in combination as needed the assembly also meets the code requirements as an air barrier. THERMAX Insulation in Low Humidity Applications THERMAX Insulation products offer several advantages in low humidity applications: High R-value (R-6.5 at one inch) Available in square or shiplap joint edge treatment Can be installed exposed to the interior without a thermal barrier (FM 4880) Delivers excellent fire performance. THERMAX products, when used in Dowapproved assemblies, meet standard fire test requirements per IBC Sections and Broad range of product thicknesses to easily meet U-value / energy code requirements Range of board lengths up to 30' to span several roof purlins or wall girts and minimize joints Easy and fast installation Easy maintenance with a range of available facers (smooth aluminum foil, embossed aluminum foil, white thermosetcoated aluminum) in a range of thicknesses and combinations *R means resistance to heat flow. The higher the R-value or RSI (R-Value Système International), the greater the insulating power. 1 UNITED STATES. COMMERCIAL TECHNICAL INFORMATION 1

2 Importance of Controlling Moisture Movement Even in low-humidity buildings, good building design means that insulation joints must be addressed. Otherwise, there is a potential for airflow through the board joints. Airflow into the building envelope can lead to reduced energy performance and condensation in the roof or wall cavity when warm, moistureladen air condenses or reaches the dewpoint. Dewpoint theory predicts condensation in a system will occur at any point where the actual and dewpoint temperature lines cross. In the following example, we look at a metal building in Chicago, IL in climate zone 5. The design conditions are as follows: interior (72.0 F at 45% Relative Humidity) and exterior (10.0 F at 72% Relative Humidity). Required U-value = 0.05 for walls (R-19 ci) Option 1: R-19 batt and no continuous insulation Option 2: R-19 batt, 1" (25 mm) THERMAX Insulation (ci) Option 3: 3" (75 mm) THERMAX Insulation (ci) only Option1 R-19 batt. Effective R-value is 12.2.* Dewpoint occurs within the cavity insulation. Dew point met in cavity. Does not meet code for ci. 2 UNITED STATES. COMMERCIAL TECHNICAL INFORMATION 2

3 Option 2 R-19 batt, 1" THERMAX Insulation with taped joints. Effective R-value is 18.9.* No dewpoint within wall assembly. No dew point. Meets code for ci. High effective R-value for increased energy efficiency. 3 UNITED STATES. COMMERCIAL TECHNICAL INFORMATION 3

4 Option 3 3" THERMAX Insulation with taped joints. Effective R-value is * No dewpoint within wall assembly. No dew point. Meets code for ci. 10% higher effective R-value for greater energy efficiency. Ease of installation & Air Sealing. NOTE: For support on running dewpoint analysis on your metal building design, contact your Dow representative. 4 UNITED STATES. COMMERCIAL TECHNICAL INFORMATION 4

5 Joint Treatment Solutions for Moisture Control To minimize moisture movement through the building envelope, use a suitable joint treatment along with the THERMAX Insulation. This includes tapes, PVC joint strips, insulation edge treatments, sealants, adhesives and air sealing foams used either singly or in combination. Here is one recommended approach: This approach not only helps protect against moisture movement, it meets air sealing and continuous insulation requirements in one package. (See Figures 1 and 2.) Figure 1: THERMAX Insulation is Ideal on walls and roofs in low humidity metal buildings Figure 2: Use a THERMAX shiplap joint with compatible sealant and THERMAX tape Materials Required: THERMAX Insulation with shiplap joint and desired facers Compatible sealant. NOTE: To produce a continuous airand moisture-vapor seal, use Vulkem 116, Sikaflex 201, Dow Corning 790 or equivalent sealant. Contact your Dow representative for more information. 3" (75 mm) THERMAX foil tape (white foil or aluminum foil depending on facer used) Corrosion resistant fasteners that penetrate a minimum 1" into framing with a 1-1/4" diameter poly washer. NOTE: When fastening to metal, use Buildex Multi- Diameter Insulation Teks or equivalent with minimum 1-1/4" poly washers (recommended). Installation: Install a bead of sealant along the long edge of the THERMAX shiplap joint and then tape the insulation joint with 3" THERMAX white foil or aluminum foil tape. Always make sure that the insulation surface is clean and dry before applying the tape. Securely fasten in accordance with the fastener manufacturer s recommendation. Other options: For interior surfaces that must be pressure cleaned or there are aesthetic requirements, use square edge THERMAX Insulation with PVC joint strips. (See Figure 3.) For an airtight seal, place a bead of compatible construction grade sealant with the joint strip. In addition, tape the back side of the board joints with 3" THERMAX white foil or aluminum foil tape. Figure 3: PVC joint strips with square edge THERMAX Insulation 5 UNITED STATES. COMMERCIAL TECHNICAL INFORMATION 5

6 Roof-Wall Air Sealing Solutions Used in conjunction with THERMAX insulation, an air sealing foam such as FROTH-PAK Foam Insulation kit* works on larger gaps such as at the wall/roof junctions. Easyto-install, FROTH-PAK Foam Insulation is a two-component, quick-cure polyurethane foam that fills cavities, penetrations, cracks and expansion joints to help create an airtight seal. FROTH-PAK insulation can be left exposed in non-fire-resistant rated roof/wall junctures (max. 6" high and 2" deep, unlimited width) per NFPA 286 Testing. High Temperature/Low Humidity Buildings Where the roof temperature may exceed 150 F, we recommend using two layers of THERMAX Insulation to separate the PVC joint strip from a roof system s exterior metal. Key Learnings THERMAX Insulation is an ideal choice in low humidity metal buildings. Not only can it meet energy code requirements for continuous insulation and air barriers, the high R-value/inch can help manage the dewpoint. THERMAX Insulation comes in a range of thicknesses and lengths to make installation quick and easy. FROTH-PAK Foam Insulation kit makes it easy to seal larger gaps or hard-toaccess areas such as roof/wall junctures. Available facers make maintenance easy and depending on the code, no additional thermal barrier is required. For Technical Information: BLUE (2583) For Sales Information: THE DOW CHEMICAL COMPANY. Dow Building Solutions. 200 Larkin. Midland, MI Illustrations are not intended to replace the need for design by appropriate professionals such as architects or engineers. NOTICE: No freedom from 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 or regions. 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 EXPRESS WARRANTIES ARE GIVEN EXCEPT FOR ANY APPLICABLE WRITTEN WARRANTIES SPECIFICALLY PROVIDED BY DOW. ALL IMPLIED WARRANTIES INCLUDING THOSE OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED. 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 BLUE (2583) or contact your local building inspector. In an emergency, call WARNING: Rigid foam insulation does not constitute a working walkable surface or qualify as a fall protection product. 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 BLUE (2583) or contact your local building inspector. In an emergency, call in the U.S. or in Canada. 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 self-contained breathing apparatus). Spraying large amounts of foam indoors may require the use of a positive pressure, air-supplying respirator. Contents under pressure. 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. Printed in U.S.A. Form No MCK McKAY *Read the label and Material Safety Data Sheets carefully before use. 6 UNITED STATES. COMMERCIAL TECHNICAL INFORMATION 6