At Childress & Cunningham Architects, we commonly perform construction management for a project we design, and therefore get to know each structure down to the smallest details.  This allows regular refinement in our construction approach, including this clever solution for the installation of basement insulation.

Typically in a residence, the basement wall formwork is  8′-0″ above the footing.   A  4″ basement slab rests on top of the footing, while a 2x wood plate adds 1 1/2″ to the top of the wall.  The net result is an interior ceiling height to the bottom of the structure of 7′-9 1/2″.  Insulation foam (and many other materials, for that matter) commonly come as an 8′ sheet, which must be cut to fit.

The design approach we have used successfully in several projects is to call for a double sill plate on top of the wall.  The substrate under the basement slab is held to 1″ lower than the top of the footing, so that the slab thickness when poured will be 3″ over the footing.

This results in a taller interior height of 8′-0″.  Further, the rigid insulation boards can be inserted to a tight fit without the mess and time for cutting and fitting,  making a finished lower level easier and less expensive to achieve.

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