A CI wall system places insulation on the exterior side of your structural framing. This approach wraps the building in an unbroken thermal layer. The result is a dramatically reduced thermal bridge at studs, plates, and headers.
Traditional cavity insulation leaves steel or wood framing exposed to temperature differentials. Those framing members conduct heat directly through your envelope. Research from building science organizations shows thermal bridging can account for up to 30 percent of heat loss in insulated buildings.
For architects specifying exterior assemblies, CI systems address this gap. They also simplify moisture management by keeping the dew point outside the structural cavity. That consistency shows up in long-term durability and occupant comfort.
Thermal bridging occurs wherever a conductive material bypasses your insulation layer. In framed walls, studs create direct pathways for heat transfer. The effective R-value of your assembly drops significantly as a result.
Consider a 2x6 wood-framed wall with R-19 cavity insulation. The framing fraction typically runs around 25 percent. That means one quarter of your wall area performs at R-6 instead of R-19. Your whole-wall R-value drops to roughly R-13.
Steel framing amplifies the problem. Metal conducts heat far more efficiently than wood. Without exterior CI, steel-framed walls can lose 50 percent or more of their rated insulation value.
Energy codes reference clear-field R-values, but real performance depends on whole-wall calculations. The International Energy Conservation Code and ASHRAE 90.1 both recognize this reality. Many jurisdictions now require either prescriptive CI values or performance-based calculations.
Meeting code means documenting your assembly's true thermal performance. That requires accounting for framing, fasteners, and penetrations. CI systems give you a straightforward path to compliance by addressing the exterior layer directly.
Selecting the right insulation material depends on your project's thermal targets, moisture exposure, and fire requirements. Each option brings specific trade-offs.
EPS delivers R-4.2 per inch at 75°F. It offers predictable thermal performance across temperature ranges. EPS also absorbs and releases moisture without losing R-value, making it forgiving in real-world conditions.
Old Mill Building Products uses EPS foam panels in the Panel+ Wall System. The material accommodates built-in drainage channels and precise veneer alignment. Standard thicknesses range from 1 inch to 4 inches, with custom options available for projects requiring higher R-values.
XPS delivers slightly higher R-value per inch, typically R-5. It resists moisture absorption more than EPS. However, its vapor impermeability can complicate drying potential in some assemblies. XPS works well below grade or in high-moisture applications.
Polyiso offers the highest R-value per inch among common rigid foams, around R-6 at standard temperatures. Performance decreases in cold weather, so architects in heating-dominated climates should factor in temperature derating. Polyiso requires attention to fire protection detailing.
Mineral wool delivers fire resistance and vapor permeability in one material. R-values run around R-4 per inch. The material's density supports direct cladding attachment in some assemblies. Mineral wool also allows assemblies to dry in both directions, reducing moisture accumulation risk.
Window and door openings represent critical transition points in your CI assembly. Getting these details right determines long-term water management and thermal performance.
Decide where your window sits relative to the CI layer. Three common approaches exist: inboard of the insulation, outboard at the face of insulation, or centered in the insulation thickness. Each position affects flashing, trim, and thermal bridging.
Inboard positions create a deep exterior recess. That recess needs careful flashing at jambs and sill. Outboard positions minimize the recess but require robust head flashings to shed water away from the CI face.
Apply a sloped sill pan before setting the window. The sill flashing should extend onto the face of the CI or integrate with a sub-sill that does. Back dams prevent water from entering the wall cavity. End dams direct water toward drainage paths.
Use a fluid-applied membrane or pre-formed pan for reliable results. The sill must slope to drain. Standing water at this junction leads to deterioration over time.
Jamb flashings lap over the sill pan and extend up the full height of the opening. They should tie into your weather-resistive barrier behind the CI layer. Head flashings cap the assembly and direct water outward.
Coordinate flashing materials with your CI type. Self-adhered membranes work well on most substrates. Some foams require compatible adhesives or primers for reliable bond.
Terminate your CI neatly at the window frame. Some systems use extension jambs that bridge from the window to the CI face. Others rely on trim profiles that cap the foam edge. The goal is a weather-tight connection that allows the cladding to terminate cleanly.
Top and bottom of wall represent two more critical transition points. Each requires careful coordination between structural, thermal, and moisture control layers.
At the base of wall, CI should extend down to cover the rim joist or slab edge. Terminating above the rim joist creates a thermal short circuit at the floor line. Extend insulation low enough to maintain envelope performance.
Protect exposed CI with a durable finish below grade or in the splash zone. Code-approved coatings, metal flashings, or cementitious finishes prevent UV degradation and physical damage. Coordinate with your drainage plane to direct bulk water away from the foundation.
At roof transitions, CI should meet roof insulation without a gap. Coverage at this junction prevents a thermal bridge. Parapets require CI on both interior and exterior faces to avoid becoming cold fins that conduct heat from conditioned space.
Coordinate your air barrier at these transitions. Seal the wall air barrier to the roof membrane. Continuity at this junction prevents stack-effect air leakage that undermines your thermal strategy.
Moisture control in CI assemblies depends on three strategies: keeping bulk water out, managing vapor diffusion, and allowing drying when wetting occurs.
Your primary defense against bulk water is a drainage plane behind or integrated with the cladding. Water that penetrates the outer layer needs a clear path down and out. Drainage channels or mat systems create that path.
Panel+ EPS foam panels from Old Mill Building Products incorporate cross-drainage channels directly into the insulation. This design facilitates water evacuation and supports drying of the drainage plane. The built-in channels eliminate the need for separate drainage mat products in many assemblies.
Your weather-resistive barrier sits between the sheathing and the CI layer. In a fluid-applied adhesive installation method, Old Mill Air & Water Barrier applies directly to approved substrates, creating a monolithic membrane that also serves as the air barrier.
Vapor control strategy depends on climate zone. In cold climates, vapor retarders on the interior side prevent moisture-laden indoor air from reaching cold surfaces. In mixed climates, vapor-permeable assemblies allow drying in both directions. Coordinate your CI permeability with overall wall vapor profile.
Every wall assembly gets wet sometimes. Successful walls dry before moisture causes damage. CI systems that allow some vapor permeability support outward drying. Ventilated rainscreen cavities accelerate drying behind cladding.
Balance drying potential against thermal performance. Highly vapor-permeable CI materials may require thicker applications to hit R-value targets. The goal is an assembly that manages both heat flow and moisture safely.
Cladding attachment through CI presents structural and thermal challenges. Your approach depends on cladding weight, CI thickness, and thermal bridging tolerance.
Lightweight claddings like fiber cement siding can attach through CI up to 4 inches thick using long screws into framing. Fastener length increases thermal bridging. At some point, the thermal short through metal fasteners offsets gains from thicker CI.
Calculate your effective R-value with fasteners included. Software tools and published guidance from insulation manufacturers help model this trade-off. For most residential and light commercial projects, 1-2 inches of CI with standard fasteners delivers significant improvement over cavity-only insulation.
Heavier claddings like thin brick, stone, and tile require more robust attachment. Substructure systems use clips or rails that penetrate the CI and anchor to framing. The substructure then receives the cladding.
Panel+ from Old Mill Building Products takes a different approach. The EPS foam panel includes built-in alignment grooves for thin brick, stone, or approved tile veneer. The veneer adheres directly to the panel face using Old Mill Adhesive. This method eliminates separate substructure, reduces labor coordination, and maintains a cleaner thermal envelope.
Thermally broken clips minimize heat transfer through attachment points. These systems use materials with lower conductivity than steel, or they incorporate thermal breaks in the clip assembly. The result is a substructure that supports cladding while limiting thermal bridging.
Thermal clip systems add cost and complexity. They make sense for thick CI assemblies where standard fasteners would create significant thermal shorts. Weigh the thermal benefit against installation time and material expense.
NFPA 285 is the fire test standard for exterior wall assemblies containing combustible components. If your CI material is combustible, your assembly must pass this test to meet code requirements for Type I through IV construction.
The NFPA 285 test subjects a two-story mock-up wall to a fire inside a lower-floor window opening. The assembly must prevent flame spread up the exterior wall and limit fire propagation into the upper floor. Test criteria include temperature rise, flame extent, and observation of fire spread behavior.
Passing assemblies earn specific listings that define every component: insulation type and thickness, sheathing, barrier, cladding, and fasteners. Substitutions outside the tested assembly void the listing.
When specifying CI assemblies, confirm NFPA 285 compliance for your specific combination of materials. Panel+ Wall System assemblies have been tested to NFPA 285 requirements. This testing gives architects confidence that the specified assembly meets fire code without custom engineering.
Document your assembly clearly in specifications. Reference the test report number and list all tested components. Inspectors will verify compliance against these documents during construction.
Installation sequence matters. Following the correct order ensures your air barrier, insulation, drainage, and veneer work together as designed.
Start with approved sheathing installed over framing. Acceptable substrates include exterior-grade gypsum sheathing, concrete, masonry, and other approved materials. Surfaces must be clean, dry, and free of debris.
For the fluid-applied adhesive method, apply Old Mill Air & Water Barrier to the sheathing. This creates your weather-resistive barrier and air barrier in one application. Allow proper cure time before proceeding.
Comb Old Mill Adhesive vertically with a 1/2-inch notch trowel. The vertical combing pattern creates drainage channels that supplement the built-in panel channels. Set Panel+ EPS foam panels into the adhesive, aligning edges and maintaining level courses.
For the mechanically fastened method, install a drainable building wrap first. Then attach panels using Old Mill washers and approved fasteners driven into framing. Both methods achieve the same thermal and drainage performance.
Flash all window and door openings as described earlier. Seal penetrations for pipes, conduits, and vents with compatible sealants or flashing. Maintain air barrier continuity at every transition.
Terminate panels neatly at top and bottom of wall. Coordinate with foundation protection and roof membrane tie-ins. Every edge and junction needs attention.
Panel+ panels include alignment grooves that guide veneer placement. Apply Old Mill Adhesive to the panel face and set thin brick, stone, or approved tile into the adhesive. The built-in alignment ensures consistent spacing without separate spacers or layout tools.
Work from bottom to top, pressing each unit firmly into the adhesive. This field-installed veneer approach delivers the look of traditional masonry without the weight or installation complexity of full-thickness materials.
Traditional exterior assemblies require multiple trades and sequential operations. CI systems that integrate functions into fewer components compress schedules and reduce coordination burden.
Panel+ reduces labor time by up to 60 percent compared to traditional lath and scratch methods. Crews skip the steps of installing separate drainage mat, applying scratch coat, and waiting for cure times. The panel delivers insulation, drainage, and veneer alignment in one product.
For builders managing schedule pressure, this consolidation matters. Faster crews mean earlier dry-in. Earlier dry-in means interior trades can start sooner. The schedule benefit compounds through subsequent phases.
Fewer components mean fewer handoffs between trades. The same crew that installs Panel+ can also install the thin brick veneer. No mason required for the wall system installation. This simplification reduces coordination burden and limits the delays that occur when trades wait for each other.
For contractors and builders, reduced callbacks also factor into labor calculations. Integrated systems with tested assemblies perform predictably. That predictability shows up in fewer warranty issues and lower long-term service costs.
Clear specifications prevent substitutions that undermine performance. Your documents should address materials, performance requirements, installation methods, and quality assurance.
Name approved products or establish performance criteria that candidate products must meet. For CI materials, specify R-value per inch, vapor permeability, compressive strength, and fire classification. Reference applicable ASTM standards for each material type.
For integrated systems like Panel+, specify the complete system including adhesives, fasteners, barriers, and veneer options. Single-source systems reduce substitution risk and ensure component compatibility.
State required whole-wall R-value, air leakage rate, and water penetration resistance. Reference test methods: ASTM E2178 for air barriers, ASTM E331 or E1105 for water penetration. For fire performance, cite NFPA 285 and list acceptable tested assemblies.
Include performance requirements for thermal bridging. Some specifications now call for calculated whole-wall R-values that account for framing and fastener impacts.
Reference manufacturer installation guides as the basis for workmanship standards. Require installer training or certification where available. Specify inspection hold points for air barrier application, flashing installation, and final veneer placement.
Include provisions for submittal review, mock-up construction, and field verification. Mock-ups at window openings and wall transitions let you verify detailing before full-scale installation proceeds. Field air barrier testing catches defects before they become hidden in completed assemblies.
Panel+ was developed to solve the practical challenges architects and builders face when specifying CI wall systems. The system integrates multiple functions that traditionally required separate products and coordination between trades.
Panel+ EPS foam panels include engineered drainage channels. Water that reaches the panel face drains down through these channels and exits at the base of wall. The channels also support ventilation behind the veneer, helping the assembly dry when wetting occurs.
Traditional thin brick and stone applications over CI require separate substructure systems for attachment and alignment. Panel+ eliminates that step. The panel face includes alignment features that guide veneer placement directly. Crews achieve consistent coursing and joint width without additional layout effort.
Panel+ supports both fluid-applied adhesive and mechanically fastened installation methods. This flexibility lets you match the method to project conditions and crew capabilities. Both methods deliver tested performance with documented NFPA 285 compliance.
Old Mill Building Products supplies all system components from sheathing out: Air & Water Barrier, Adhesive, Panel+ foam panels, fasteners and washers, and veneer products. Single-source responsibility simplifies procurement, ensures compatibility, and backs the assembly with a 15-year system warranty.
Field experience reveals recurring errors that compromise CI assembly performance. Awareness of these pitfalls helps architects and installers prevent problems before they occur.
Cutting CI to fit around pipes, conduits, and other penetrations often leaves gaps. Those gaps create thermal bridges and potential moisture pathways. Fill all gaps with compatible insulation or sealant. Plan penetration locations to minimize cutting and maximize insulation coverage.
Flashings that fail to integrate with the drainage plane trap water instead of shedding it. Lap flashings correctly: upper layers over lower layers, directing water outward at each junction. Test flashing details with water before concealing them behind cladding.
Air barrier continuity depends on proper sealing at every transition: foundation, roof, windows, doors, and penetrations. Missed seams and failed adhesion create leakage paths that undermine both thermal and moisture performance. Conduct air barrier inspections before covering the work.
Heavy cladding systems sometimes require substructure that penetrates CI with significant metal mass. Evaluate the thermal impact of your attachment strategy. Consider thermal clips or systems that minimize conductive penetrations. Balance structural requirements against thermal goals.
Detailing CI wall systems requires attention to thermal continuity, moisture management, and code compliance. Every junction, opening, and penetration presents an opportunity to maintain or compromise assembly performance.
Success comes from understanding how the layers work together: structure, air barrier, insulation, drainage, and cladding. Coordinate these elements through clear specifications and careful installation. Document tested assemblies to satisfy code officials.
Old Mill Building Products' Panel+ Wall System addresses these challenges by integrating CI, drainage, and veneer alignment into a single-source system. For architects specifying exterior assemblies, this integration reduces complexity while delivering NFPA 285-compliant, high-performance envelopes.
Ready to specify Panel+ for your next project? Contact Old Mill Building Products for technical details, assembly documentation, and project-specific guidance.
Code-required R-values vary by climate zone and building type. Commercial buildings typically require R-7.5 to R-15 for CI alone, depending on climate zone under ASHRAE 90.1. Residential codes reference similar ranges.
Check your jurisdiction's adopted code version for specific requirements.
Old Mill Building Products' Panel+ places EPS foam insulation on the exterior side of your framing. This approach eliminates the thermal bridges that occur at studs and plates in cavity-insulated walls. Panel+ delivers R-4.2 per inch, with thicknesses up to 4 inches standard and custom options available.
Yes. Many CI assemblies have been tested and listed to NFPA 285 requirements. Old Mill Building Products' Panel+ Wall System assemblies are NFPA 285 compliant. Specify the tested assembly exactly as listed to maintain code compliance.
CI systems support a range of claddings: fiber cement, wood, metal panels, stucco, thin brick, and stone. Attachment method varies by cladding weight and CI thickness. Old Mill Building Products' Panel+ is designed specifically for thin brick, stone, and approved tile veneer.
CI assemblies manage moisture through drainage planes, vapor control, and drying potential. Old Mill Building Products' Panel+ includes built-in drainage channels that direct water down and out. The system also works with Old Mill Air & Water Barrier to create a fully integrated moisture management assembly.
Old Mill Building Products' Panel+ reduces labor time by up to 60 percent compared to traditional lath and scratch methods. The integrated panel eliminates separate drainage mat installation, scratch coat application, and associated cure times. Faster installation means earlier project completion.
No mason is required for Panel+ Wall System installation. The system uses thin brick adhered directly to the panel face with Old Mill Adhesive. Built-in alignment grooves guide veneer placement. Standard construction crews can complete the installation after appropriate training.
Approved substrates vary by system and installation method. For Panel+, acceptable substrates include exterior-grade gypsum sheathing, concrete, and masonry. Old Mill Building Products' Air & Water Barrier applies directly to approved substrates in the fluid-applied adhesive method.