Another energy efficient wall solution in commercial construction is the precast concrete panel option. Also known as tilt-up walls, they can be easily and economically insulated by incorporating Plasti-Fab PlastiSpan insulation into the panel when they are manufactured. The panel can then be easily placed during the construction process, providing a fully insulated finished wall or floor section. You can imagine how much time this saves in commercial construction.
The precast concrete panel is usually constructed so the interior shell of the panel is structural and will support wind loads or any other loads expected. Since it is insulated from the weather it will not be subjected to extremes of thermal expansion and contraction and will be a more suitable unit. The windows are mounted on the interior shell which is more stable. The interior shell acts as a heat source for the window, warming it and allowing for a higher relative humidity in the building before condensation occurs on the window.
How are the walls made?
The panel is usually poured exterior face down so any architectural details can be incorporated into the mould. Concrete is poured over the exterior shell reinforcing to the depth required for the thickness of the exterior skins, then vibrated as necessary. Shear ties are worked into the wet concrete or in some cases the shear ties are placed as the concrete is poured.
Some designs require a bond breaker between insulation and exterior shell. 2 mil polyethylene will provide this requirement. PlastiSpan insulation boards are placed over the wet concrete allowing space for concrete web around perimeter where necessary. Reinforcing for the inner shell is placed. To complete the wall, concrete is poured to finished thickness of panel, again vibrating as necessary. The surface of concrete is troweled as required. The concrete is allowed to set and cure as normal, and then the panel is ready to be handled as usual.
The total thickness of concrete in the panel is usually accepted in order to determine the fire rating of the panel. Fire testing to verify this rating has been completed in other countries. Where the panels are designed for long spans it is desirable to separate the PlastiSpan insulation along the length of the panel to divide the flammable component into two or more compartments.
A spray-on finish is standard for a ceiling finish on the underside of the panel. When used as a roof panel the insulation on the panel may be used to calculate the thermal resistance over the area to be covered by the roof. Additional insulation over the slab is often required in conjunction with the roof membrane to reduce the effect of the thermal short at the concrete webs. We will cover the Plasti-Fab roofing insulation solutions a little further along in this blog series.
To learn more about these Tilt-up walls as a solution to your commercial construction project, contact us today. 1-88-THINK EPS® or visit http://www.plastifab.com