Structural Insulating Wall Panels (SIPs)

DEFINITION
CONSIDERATIONS
COMMERCIAL STATUS
IMPLEMENTATION ISSUES
GUIDELINES

  1. Ordering Panels
  2. Panel Details

CSI NUMBER:

07410 Preformed Wall & Roof Panels


DEFINITION

Structural panels are typically two outer layers of structural sheathing material separated by an insulated core. They are made in different sizes according to the job’s requirements.


CONSIDERATIONS:

Structural panels replace the standard stud/insulation/sheathing wall system. Some panels have sheetrock mounted on the inside portion, and/or siding on the exterior. Most have sheathing such as OSB for facings.

Panels can be fabricated with three types of foam cores: molded expanded polystyrene (MEPS), extruded polystyrene (XEPS), and urethane (polyurethane and polyisocyanurate are types of urethane). There are several options for facings: plywood, waferboard, oriented strand board (OSB), sheetrock, and metal. Exterior surface materials such as T-1-11 siding are offered by some suppliers. XEPS and urethane foam use CFC’s or HCFC’s as blowing agents. MEPS does not use any ozone-depleting chemicals. For credit from the Green Builder Program for this option, MEPS insulation or an alternative that has no ozone-depleting chemicals must be used. Additionally, waferboard, OSB, sheetrock and/or siding need to be used as facings.

Foam insulation can attract insects. Some companies use borates as an insect barrier in the foam insulation. This is a preferred strategy for protecting the panels. Borates are also topically applied to the facings by some companies.

Structural grade adhesives should be used to bind the facings to the foam core. Use the manufacturer warranty as a gauge of the quality of the product. Poor adhesive qualities can cause panel failure. Select panels that are certified to meet building codes.

Structural panels offer very effective insulating qualities, rapid installation, and consistent quality (minimizing waste). The use of OSB or waferboard for facings is considered a positive use of wood resources.

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Structural Wall Satisfactory in most conditions Satisfactory in most conditions Satisfactory in most conditions Satisfactory Satisfactory Satisfactory in Limited Conditions
Satisfactory Satisfactory
Satisfactory in most conditions Satisfactory in most conditions
Satisfactory in Limited Conditions Satisfactory in Limited Conditions
Unsatisfactory or Difficult Unsatisfactory or Difficult


COMMERCIAL STATUS

Technology:

Many manufacturers make structural panels. Quality control is inconsistent in the industry and product development is continuing.

SUPPLIERS:

Available locally and regionally.

COST:

$1.75 to $2.75 per square foot or higher (material only). This can be slightly higher than conventional framing costs.


IMPLEMENTATION ISSUES

FINANCING:

Available if panels are code compliant.

PUBLIC ACCEPTANCE:

Good

REGULATORY:

Not all panels have been tested for code compliance. Make certain that the panel as a whole is code compliant, not just the components of the panel. This information is provided by the manufacturer.


GUIDELINES

1.0 Ordering panels

Specify MEPS with borate treatment for insulation or other non ozone-depleting insulation.

Use waferboard or OSB facings. These materials do not contain urea formaldehyde or outgas toxic materials.

Window and door openings can be provided by some manufacturers.

Drywall can be provided already mounted by some manufacturers. Some panel manufacturers also offer exterior wall surfaces, typically T-1-11.

Sandwich panels (two facings) and unfaced panels are available. Unfaced panels typically have structural members (i.e. studs) in the insulation. Facings are added on-site.

Use panels that have structural grade adhesive linking the cores with the facings.

Panels can be used as infill in a post and beam structure.

2.0 Panel details

To groove or notch panels to fit together; a hot knife, hot wire, or router can be used.

Caulk guns are a necessity.

An oversized saw is useful for cutting panels.

If openings are not factory supplied, a chainsaw can be used.

Expect to use a large assortment of straps and reinforcing brackets.

While storing panels, protect them from rain and keep them ventilated (particularly in hot, sunny locations) by using “sleepers”, or spacers, between panels.

Stack panels so that the sequence of removal accommodates the order they need to be erected.

Examine panel details from the manufacturer in regards to installation; many variations exist. In connecting panels, choose systems that do not compromise the thermal qualities of the panel by creating a thermal bridge or “short circuit”.

There should be a gap between panel sections so facings have room to expand.

When creating openings (i.e. windows), the foam must be cut back from the edge of the facings in order to infill with 2X material. With MEPS this is most quickly done with a router and a hot knife in the corners. This is a slow process with only a hot knife.

Wiring and plumbing chases are typically provided by the panel manufacturer at specified distances along the panel.