Dow Inverted Wall Assembly - Welcome To TAYLOR .

The Use of STYROFOAM Brand Insulationin the Commercial Inverted Wall AssemblyThis commercial assemblyaddresses the needs ofall building enveloperequirements:Metal Framing(Cavity Insulation Optional)STYROFOAM Brand XPS InsulationUltra SL or STYROFOAM Brand XPSInsulation CAVITYMATE SC Fire performance (NFPA 285) Continuous Insulation/Thermal efficency Weather-resistive barrier(WRB) Durability/security Air barrier with appropriatedetailing with the WRBGeneral DescriptionThe Inverted Wall Assembly is a new configuration of a wellestablished exterior commercial wall design. For over 45 years,designers and architects have used STYROFOAM Brand XPSInsulation, an exterior insulating sheathing for metal frame curtainwall design, with many exterior claddings including stucco, brickand ACM Panels. The standard curtain wall design starts with alayer of exterior gypsum sheathing attached to the metal framingfollowed by a weather-resistive barrier, a layer of STYROFOAM Brand XPS Insulation, and lastly, the exterior cladding attached overboth sheathing layers. This provides architects with the structural,durable, fire-resistant performance they expect from the gypsum andthe superior energy savings, moisture management and moistureprotection they desire from STYROFOAM Brand XPS Insulation.This long-used assembly, now reconfigured as the STYROFOAM Inverted Wall Assembly, meets the NFPA 285 fire test. The layers arerearranged to attach STYROFOAM Brand XPS Insulation directlyto the metal framing and then gypsum sheathing is attached overthe insulation. An approved weather-resistive barrier (see JensenHughes Engineering Judgment letter “Exterior Wall Analysis – Use ofGypsum Sheathing Over XPS Insulation in NFPA 285 Complying WallAssemblies”) is then applied over the gypsum sheathing.Exterior Gypsum SheathingApproved Weather-resistiveBarrierExterior Cladding Such as FireResistant ACM PanelThe assembly extends the number of veneers, including fire sensitivecladdings like ACM panels, which can be used to comply with theNFPA 285 acceptance criteria as required by the building code. Thedesign methodology for the attachment of gypsum sheathing, furringsystems and exterior cladding systems through foam sheathing iswell understood and documented in Section 2603.12 of the 2015International Building Code (IBC). This is an important facilitator toachieving and complying with continuous insulation requirementsof the IBC. The basic wall design, with the the exterior cladding overgypsum sheathing and STYROFOAM Brand XPS Insulation on metalwall framing, is shown in Figure 1.Contact your building envelope expert at Dow to access the wallassembly details and component options provided in the JensenHughes Engineering Judgment letter “Exterior Wall Analysis – Useof Gypsum Sheathing Over XPS Insulation in NFPA 285 ComplyingWall Assemblies.”

Approved STYROFOAM Brand XPSInsulation ProductsSTYROFOAM Brand Ultra SLR-value at 75F meantemp ASTM C518/ASTM C578Water ResistanceASTM C272Edge DetailR-122.18”R-142.5”R-16.83”Superior Energy Savings0.3% max.Wall durabilityShip-lap edge onlong sideEnergy efficiency &resist moisture intrusionSTYROFOAM Brand Square Edge WideR-value at 75F meantemp ASTM C518/ASTM C578It is important to consider minimizing the total number offasteners used to attach the insulation and gypsumsheathing to ensure optimal thermal efficiency.Water ResistanceASTM C272Edge DetailR-5.01”R-7.51.5”R-102”Energy Savings0.3% max.Wall durabilityShip-lap edge onlong sideEnergy efficiency& resist moisture intrusionWall Assembly GuideProject sequencing is important to limit the exposure ofSTYROFOAM Brand XPS Insulation to a maximum of 90 daysbefore covering with gypsum sheathing. The gypsum sheathing andweather-resistive barrier layers should not be exposed longer thanmanufacturer recommendations.Substrate PreparationsSteel framing shall be designed, installed and braced permanufactuer requirements. Maximum steel stud spacing for thiscommercial wall assembly is 24” oc.The installation of STYROFOAM Brand XPS Insulation, gypsumsheathing, furring system and wall cladding can begin once themetal wall framing and bracing have been installed. Considerationshould be given to construction sequencing to minimizing thenumber of fasteners used to fasten STYROFOAM Brand XPSInsulation and gypsum sheathing to minimize thermal shorts.The design methodology for the attachment of exterior claddingsthrough foam sheathings is well understood and can comply withthe IBC. This document summarizes the minimum fasteningrequirments when attaching exterior claddings, furring systemsand gypsum sheathing over STYROFOAM Brand XPS Insulation onsteel wall framing. This is an important enabler to achieving andcomplying with continuous insulation requirements.Attachment of STYROFOAM Brand XPS InsulationSTYROFOAM Brand XPS Insulation shall be positionedhorizontally or vertically with the metal framing. Use corrosionresistant self-tapping screws with washers such as the RodenhouseGrip-Deck self-drilling screw with PlastiGrip or Thermal-Gripwashers. See manufacturer’s recommendations on specificfastener size for the thickness of STYROFOAM to be installed.It is important to consider minimizing the total number offasteners used to attach the insulation and gypsum sheathing toensure optimal thermal efficiency. The number of fasteners isbased on wall installation sequencing and local weather conditionsexpected during the wall construction process. STYROFOAM Brand XPS Insulation need only be fastened with the minimumnumber of fasteners to hold it in place until the gypsum sheathingis installed. If the elapsed time between insulation installation andgypsum installation is sufficiently brief and weather conditionsare sufficiently mild, as determined by Project ConstructionManagement, STYROFOAM Brand XPS Insulation may be installedwith as few as 5 fasteners, one in each corner and one in themiddle of the board along a stud line. The gypsum sheathingshould be installed before weather conditions arise that wouldrequire additional securement for the STYROFOAM Brand XPSInsulation boards. Where weather conditions cannot be predicted,4’x8’ boards of STYROFOAM Brand XPS Insulation should beinstalled with fasteners 12”oc around the perimeter of the walland 16”oc in the field of the wall. Fasteners should be set back 3/8”from edges and ends of the insulation boards.

Attachment of the Gypsum SheathingFor NFPA 285 compliant assemblies with fire sensitive veneers,5/8” Type X gypsum sheathing is required to be installed over theSTYROFOAM Brand XPS Insulation. The fastening of the gypsumsheathing shall be per manufacturer’s recommendations. Again, itis important to consider minimizing the total number of fastenersused to attached the gypsum sheathing and furring/claddingattachment systems for optimum thermal efficiency. In manycases a metal furring or metal cladding attachment system willbe installed over the gypsum sheathing with a defined fasteningpattern required to meet structural and attachment requirementsfor the exterior cladding. All fasteners used for gypsum sheathing,furring and cladding attachment systems should be securelyfastened back to the metal framing structure as per manufacturerrecommendations. When furring or cladding attachment systemsare used, Project Construction Management may determine ifconditions allow the fastening pattern of the gypsum sheathing tobe reduced with the subsequent required fasteners used to securethe furring/cladding attachment system.The design requirements for the attachment of gypsum sheathing,furring and exterior claddings over foam sheathing on steelwall framing is specifically addressed in Section 2603.12 of the2015 IBC. The design methodology is also documented in theDr. J Engineering Technical Evaluation Report TER No. 1303-04“Attachment of Exterior Wall Coverings Through Foam PlasticInsulating Sheathing (FPIS) to Wood or Steel Wall Framing” sulating-sheathing-fpis-wood-or).Application of Weather-Resistive Barrier (WRB)Install the Weather-Resistive Barrier (WRB) as per manufacturerrecommendations over the gypsum sheathing. Where requiredas an Air Barrier, follow manufacturer recommendations onsealing details.Attachment of Furring and/or CladdingAttachment SystemsInstall metal furring or metal cladding attachment systemsover the WRB covered gypsum sheathing as per manufacturerrecommendations. All fasteners used for metal furring andmetal cladding attachment systems should be securely fastenedback to the metal framing structure as per manufacturerrecommendations. The design requirements for the attachmentof metal furring, metal cladding attachment systems andexterior claddings over foam sheathing on steel wall framingare specifically addressed in Section 2603.12 of the 2015 IBC. Thedesign methodology is also documented in the Dr. J EngineeringTechnical Evaluation Report TER No. 1303-04 “Attachmentof Exterior Wall Coverings Through Foam Plastic InsulatingSheathing (FPIS) to Wood or Steel Wall Framing” sulating-sheathing-fpis-wood-or).The 2015 IBC design table for attaching metal furring for exteriorcladding over foam plastics is provided below:IBC Table 2603.12.2 Furring Minimum Fastening Requirements for Application Over Foam Plastic Sheathing to Support Cladding rType andMaxiumumSizeb#8 screw33 milsteel stud#10 screwMinimum33 milsteelfurring#8 screw43 milsteel stud#10 screwFastenerSpacingin Furring(inches)Maximum Thickness of Foam Sheathingc (inches)16” oc furringd24” oc furringdCladding WeightCladding Weight3 psf11 psf25 psf3 psf11 psf25 l furring shall be minimum 33 ksi steel. Steel studs shall be minimum 33 ksi steel for 33 mil thickness and 50 ksi steel for 54 mil steel or thicker.bScrews shall comply with AISI S200. Minimum penetration into steel framing is steel thickness plus 3 threads.cFoam sheathing shall have a minimum compressive strength of 15 pounds per square inch in accordance with ASTM C578.dFurring shall be spaced not more than 24 inches on center, in vertical or horizontal orientation. In a vertical orientation, furring shall be located over wall studs and attached with the required fastenerspacing. In horizontal orientation, the indicated 8-inch and 12-inch fastener spacing in furring shall be achieved by the use of two fasteners in studs at 16 inches and 24 inches on center, respectively.DR Design required.a