Wood or Metal Joist Frame Floors

Where walls separating adjacent but independently heated dwelling units occur, use insulation with a thermal resistance of at least R-

11. The insulation may be placed in either wall or divided propor­tionally between them (Figure 3-19).

Wood or metal joist floors over unheated basements or vented crawl spaces should have a maximum U-value of 0.07 (requiring insulation rated at R-11 or greater). Three methods for providing insulation are illustrated in Figures 3-20 through 3-22.

Wood or Metal Joist Frame Floors

Figure 3-19 Walls between adjacent separately heated dwelling units.

Wood or Metal Joist Frame Floors

Wood or Metal Joist Frame Floors

Figure 3-22 Frame floor construction with rigid insulation panels attached to the bottom of the joists.

Wood or Metal Joist Frame FloorsConcrete Floors

Concrete floors over unheated spaces should have a maximum U-value of 0.11, requiring insulation rated at R-7 or greater. The following three methods are recommended for applying a layer of insulation:

1. Spray rigid insulation in a suitable thickness on the underside of the floor.

2. Bond preformed rigid insulation to the top or bottom of the surface.

3. Form concrete around a core of rigid insulation.

Posted in Audel HVAC Fundamentals Volume 1 Heating Systems, Furnaces, and Boilers