SIPs - Structural Insulated Panels

Structural Insulated Panels

Structural Insulated Panels, or SIP’s, are a cost-competitive, energy efficient and labor-saving way to enclose an historic timber frame. They are basically panelized walls, replacing in one step — framing, sheathing, insulating and drywall installation.

The panels are pre-cut to size, often also with pre-cut door and window openings. They are screwed to the timber frame and are able structurally to span large areas. At the same time, the drywall can be pre-installed between the panels and the frame, eliminating the need for time-consuming installation around the timbers from the interior.

Comparative R-values

When it comes to the insulative properties of structural panels, the stated R-value is only half the story. The monolithic construction of SIPs dramatically reduces the amount of air leakage in and out of the building. The result is that, although the panels’ R-value may only be 15-20% higher than standard insulation, the actual energy- conserving capabilities of SIPs can be as much as 40% greater than traditional stick-frame construction of walls the same thickness.

SIPs are manufactured with a variety of different foam materials: the denser the foam, the greater the R-value and the higher the price. The table below compares two common types of structural panels with traditional stick-frame construction.

Polystyrene is basically the common styrofoam found in everyday items like disposable cups and plates. This type of panel is very sufficient for most climates.

Polyurethane is a denser, heavier material than polystyrene. This type of panel is used in harsher climates and higher altitudes where sustained winter cold and wind are prevalent.