SIP Construction Guide

Based on ANSI/APA PRS 610.1-2023 Standard

What are Structural Insulated Panels (SIPs)?

SIPs are sandwich panels consisting of a foam plastic insulation core bonded between two wood structural panel facings. They are designed for use as wall panels and lintels in above-grade wall applications.

SIP Components

Core Materials

SIPs use one of three approved foam core types:

1. EPS (Expanded Polystyrene) - Type I specification

2. XPS (Extruded Polystyrene) - Type X specification

3. Foamed-in-place polyurethane - Meeting specific density and strength requirements

Facing Materials

• 7/16-inch Performance Category wood structural panels

• Oriented Strand Board (OSB) or plywood construction

• Same material and thickness on both exterior layers

Adhesives

• Laminating adhesives bond facings to core (except foam-in-place systems)

• Must be distributed over full surface contact area

• Foam-in-place systems serve as both core and adhesive

Standard SIP Dimensions

Thickness Options

• 4-1/2 inches (114 mm)

• 6-1/2 inches (165 mm)

Manufacturing Tolerances

• Thickness: +1/8 inch, -0 inches

• Width: ±1/8 inch

• Height: ±1/4 inch

• Squareness: 1/64 inch per linear foot

• Edge straightness: 1/16 inch maximum deviation

• Face alignment: ±1/16 inch

Installation Requirements

Service Conditions

• Intended for dry service conditions

• Average lumber moisture content less than 16%

• Requires weather protection with appropriate exterior coverings

Support Requirements

• Both panel facings must be continuously supported at bottom

• Must be attached to top and bottom plates

• Requires proper flashing and drainage systems

Orientation

• Wall panels: Strength axis vertical, loads applied uniformly to both facings at top

• Lintels: Strength axis horizontal, gravity loads applied equally to both facings

Connection Methods

Spline Connections

Two approved spline types for joining panels:

Box/Block Splines

• Minimum 3-inch width

• Made from same wood structural panel material as facings

• Bonded with same foam core material

• Fits into recesses at panel edges

Surface Splines

• Minimum 3-inch width

• Pair of wood structural panels

• Fit into grooves cut into foam core at panel edges

Fastening Requirements

• Use 8d common nails (0.131 x 2-1/2 inches)

• Install at 6 inches on center

• Position 3/8 inch from facing edge

• Nail heads must not penetrate facings more than 1/8 inch

Electrical Integration

Electrical Chases

• 1-1/2 inch diameter maximum

• Centered in foam core

• Must be included in structural testing

Electrical Boxes

• 4-inch by 4-inch maximum size

• Pre-cut holes in facings only

• Other penetrations beyond standard scope

Quality Requirements

Performance Standards

SIPs must meet minimum requirements for:

• Axial load capacity

• Transverse load capacity

• Racking resistance

• Lintel load capacity (when applicable)

• Bond strength between facings and core

• Construction moisture effects

Testing Requirements

• Full-scale structural testing required

• Small-scale bend testing for characterization

• Bond strength verification

• Durability testing for foam-in-place systems

Installation Best Practices

Site Preparation

• Ensure level, square foundation

• Verify dimensional accuracy of plates and supports

• Plan panel sequence and crane access

Panel Handling

• Use appropriate lifting equipment

• Protect panel surfaces during transport

• Store panels properly to prevent moisture exposure

Assembly Sequence

1. Install bottom plates with proper fastening

2. Position first panel with temporary bracing

3. Install splines and sealants as specified

4. Continue panel installation maintaining plumb and alignment

5. Install top plates and complete connections

Weather Protection

• Install temporary weather protection during construction

• Complete exterior envelope systems promptly

• Ensure proper moisture management details

Inspection Points

During Manufacturing

• Verify core material properties and labeling

• Check facing material grade marks

• Confirm adhesive application and distribution

• Verify dimensional tolerances

During Installation

• Check foundation and plate preparation

• Verify panel orientation and alignment

• Confirm proper fastening patterns

• Inspect spline and connection details

Marking Requirements

Compliant SIPs must display:

• Manufacturer identification

• Manufacturing date or traceable marking

• Approved agency identification

• Standard compliance designation "ANSI PRS-610.1"

• Flame spread and smoke-developed indices

• "Wall" designation with rated direction marked

Limitations and Considerations

Design Limitations

• Values are from laboratory testing only

• Does not address end-use factors like wind speed, connections, creep

• Design value derivation requires additional engineering

• Combined loading conditions need separate analysis

Installation Limitations

• Requires qualified contractors familiar with SIP construction

• Weather-sensitive installation process

• Coordination required with other building systems

• Special considerations for seismic design categories

Quality Assurance

• Periodic re-evaluation required

• Production quality control testing

• Approved agency inspection and certification

• Proper material storage and handling protocols

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This guide provides general construction information based on the ANSI/APA PRS 610.1-2023 standard. Always consult qualified engineers and follow local building codes for specific project requirements.