SIPs are a composite building product, consisting of an insulating layer of rigid foam sandwiched between two layers of structural sub-straights (skins).

What are structural insulated panels (SIPs)?

What types of skins does Alaska Insulated Panels (AIP) use?

AIP SIPs are manufactured exclusively using 1/2 inch structural rated CDX plywood; unlike most other SIP manufacturers that use 7/16 inch oriented strand boards (OSB).

Why does Alaska Insulated Panels (AIP) use CDX plywood?

AIP uses 1/2” CDX plywood exclusively for its durability and strength. Although 7/16" OSB is structurally acceptable for SIPs, and is the skin of choice by most other SIP manufacturers, it is easily saturated by moisture. In Alaska where the building season is only about 100 days long, assembling swelled OSB-skinned SIPs can be very frustrating and time-consuming, which is why we use CDX plywood.

What type of foam is used for Alaska Insulated Panels (AIP)?

AIP uses low-density liquid polyurethane (PUR) system manufactured by the Carpenter Co. This system employs Solstice LBA - an environmentally-friendly blowing agent.

Physical properties for foamed-in-place 2-part polyurethane mixture meeting the following criteria:


Physical Properties for foamed-in-place 2-part polyurethane mixture meeting the following criteria:

Molded density nominal (ASTM D-1622)                                                                                                              2.3 ilb/cf

Core density nominal (ASTM D-1622)                                                                                                                    2.1 Ib/cf

Compressive resistance at yield (ASTM D-1621)                                                                                                       24 psi

Flexural Strength (ASTM C-201)                                                                                                                                 34 psi

Tensile Strength (ASTM D-1623)                                                                                                                                 56 psi

Shear Strength (ASTM C-273)                                                                                                                                     32 psi

Substrate adhesion (ASTM D-1623)                                                                                                                           35 psi

Closed Cell Content, % (ASTM D-6226)                                                                                                                       >90

Water vapor permeance of 1” thick, max (ASTM E-96)                                                                                      2.1 perm

Water absorption max. (ASTM C272)                                                                                                         0.00027 lbs/in3

Dimensional stability max. (ASTM D-2126)                                                                                     -0.6% 28days @ -20ºF

Dimensional stability max. (ASTM D-2126)                                                                                    -0.2% 28days @ 200ºF

Dimensional stability max. (ASTM D-2126)                                                                    +2.0% 28 days@ 158 ºF-95% RH

R-Value, BTU. in/hr-sf² at mean temperature 20ºF (ASTM C-518)                                                                  8.0 per inch

R-Value,² at mean temperature 55ºF (ASTM C-518)                                                                 7.09 per inch

R-Value,² at mean temperature 75ºF (ASTM C-518)                                                                 6.67 per inch

Flame Spread (ASTM E-84)                                                                                                            25 Sample thickness 6”

Smoke Density (ASTME E-84)                                                                                                      350 Sample thickness 6”

Flammability Rating (ASTME E-84)                                                                                                            UL-723 Class - 1

AIP uses a polyurethane mixture (LDB-173-I / LDA-M200-31LC) blended by Carpenter Co. This system employs Solstice LBA, an environmentally friendly blowing agent, and exceeds the requirements of IRC R316 and R613.3.1.

Are AIP SIPs structurally strong?

AIP SIPs have structural characteristics that are similar to an I-beam. When under pressure or stress, the skins are in tension and compression, while the polyurethane core resists shear and buckling.  Experiments conducted by the University of Alaska Anchorage (UAA) structural lab on SIPs used AIP’s 6½” 8-foot tall wall panel, with a 3:1 safety factor that resulted in an axial loading capacity of 7,290 per lineal foot. These tests proved AIP SIPs to be 7 times stronger than conventional 2x6 stud-framed walls. 

Will skins separate from the PUR foam?

AIP uses a process known as rapid injected mold (RIM). This process impregnates the foam into the fibers of the plywood creating a bond of incredible adhesion strength (35psi). Through an actual destructive test conducted by UAA, there were only irregular panel breaks (foam on wood or wood on foam). 

What applications are PUR SIPs used?

AIP SIPs are versatile and can be used for the total insulated building envelope including below-grade foundation and frost walls, insulated floors, exterior walls, roofs, and cantilevered soffits. 

Yes, AIP SIPs become the structural component of the building envelope including window & door openings.  When used for insulated floor and/or roof applications, structural joists, purlins, and/or trusses need to be installed to accommodate specific geographical loading, i.e. seismic, wind, and snow requirements.

Will AIP SIPs replace stick frame construction?

AIP’s manufacturing process creates one of the highest insulating R-Value per inch of all the commercially available insulating products in today’s market. AIP SIP’s provide a superior and uniform insulation in comparison to traditional insulation methods, thus providing a more airtight structure which means: fewer drafts, less noise, eliminated thermos bridging, and lower energy consumption that can reduce heating and cooling costs by up to 50%. Essentially providing a more comfortable living and working space for the entire family.

Why are AIP SIPs a superior alternative to traditional insulation?

Are PUR SIPs safe for my family, friends, and the environment?

Yes! AIP SIPs qualify for Green building projects as well as Energy Star rated construction, which is a government-sponsored program that helps promote high levels of energy efficiency.

Are PUR SIPs easy to install?

Yes! Quick and easy installation can be achieved with the use of standard construction tools. Installation instructions are provided with every order, and you can check out our video for reference. 

How are PUR SIPs joined together?

AIP SIPs are joined by either two strips of plywood called surface "splines" or by dimensional 2X lumber.  The type of spline used will be determined by properties such as wind, weight, and seismic forces.

How are windows and doors installed in PUR SIPs?

Rough openings for windows and doors are provided during building fabrication. Windows and doors are installed on-site according to the specific manufacturer's instructions.

How do you install electrical wiring and plumbing in PUR SIPs?

AIP fabricates vertical "electrical chases” and cutouts for boxes as determined by the electrical wiring plans provided. Traditionally, plumbing is kept within the interior walls and floors of your home. Installing island vents or loop vents are also a common practice and can be found in plumbing codes.

How do you attach siding to PUR SIPs?

Application of siding should be in accordance with the specific siding manufacturer's instructions including weather barrier and fastening. Typically, the frequency of fastening increases to 12" on center.

How do PUR SIPs protect against moisture?

PUR foam has a perm rating of less than 1 and is water-resistant. Therefore, it will not allow any type of moisture to penetrate the panel. The proper sealing of all panel joints during on-site construction is required.

What is "off-gassing" and does this occur with PUR SIPs?

Off-gassing is the release of chemicals from non-metallic substances under ambient or greater pressure conditions. Off-gassing can be related to what's popularly known as the "new car smell."  When PUR is encapsulated between two plywood skins and not exposed to atmospheric conditions, off-gassing cannot ensue. Cured, rigid polyurethane foam is a thermoset plastic that does not release VOCs. 

How do PUR SIPs perform in a fire?

The polyurethane foam used in AIP SIPs has a UL 723 class “1” rating, a flame spread rating of 25, and a smoke-developed rating of 300. PUR is a cross-linked thermoset plastic that is highly resistant to heat - capable of withstanding temperatures up to 800 ºF (427 ºC). When exposed to high temperatures, the PUR only chars - it does not melt. In residential applications, building codes require the interior surface of any foam products must be covered with a 15-minute thermal barrier.

Are PUR SIPs toxic in a fire?

Polyurethane foam is organic; the major toxic material emitted when burned is the same as any organic material: Carbon Monoxide and Carbon Dioxide. 

What is the cost of PUR SIPs per square foot?

AIP SIP buildings are engineered to specific building plans and geographic load (snow, wind & seismic) requirements; therefore, the cost per square foot is a variable. The superior insulation performance of AIP SIP’s allows for thinner walls, which means increased living space when compared to conventional buildings that have the same exterior dimensions. To get a free estimated cost for your specific plan, please fill out the info on our contact page or call Alaska Insulated Panels at 1-907-357-2769.

AIP SIPs are manufactured using the latest state-of-the-art equipment by placing two (2) preheated structurally-rated skins in a specifically designed mold. The mold is placed in a hydraulic press and injected with a 2-part polyurethane (PUR) liquid. Once mixed and injected it expands up to 50 times its volume in about 8 seconds, generates up to 15 pounds per square inch of pressure, and temperatures in excess of 300°F.  During the curing process, the hydraulic press counters the generated forces of the foam and maintains the desired panel thickness while the pressure and heat impregnate the foam into the fibers of the skins, creating a bond that is almost indestructible. Once the foam has bonded and fully cured it becomes a thermal set closed-cell plastic that will not melt and has incredible structural strength.

How are PUR SIPs manufactured?

What is the difference between PUR and Expanded Polystyrene (EPS) SIPs?

Comparing AIP’s PUR SIP to an EPS glued sandwich SIP is akin to comparing apples to oranges. The difference in the technology and thermal performance of the foams used is like night and day. SIPs, like all manufactured products, are only as strong as its weakest link. The more components used in the manufacturing process increases the risk of failure. For example; Polyurethane is glue and when injected as a liquid into the SIP mold, the heat and pressure created by the curing process impregnates the foam into the fibers of the plywood skins. AIP’s PUR foam core SIP is a two-component molded panel whereas an EPS SIP is a three-component glued sandwich panel. Polyurethane is also a glue and is oftentimes used by EPS manufactures for gluing their sandwiched panels. It comes down to this: all buildings constructed in northern cold-climate regions like Alaska have movement, be it from seismic (earthmoving), wind pressure (lateral), thermal expansion or contraction (heat/cold), and differential settling (ground/soil).  The weakest link of the EPS SIP is the glued joint, and over time this joint will fail.

What is AIP's SIP warranty?

AIP PUR SIPs have a 20-year limited warranty that provides comprehensive coverage from defects in the manufacturing, materials, and workmanship. 

Are AIP SIPs made in Alaska?

Yes, AIP SIPs are manufactured and fabricated in Wasilla, Alaska. Everyone is invited to tour our plant; just call 907-357-2769 to make an appointment.