TM 5-852-4/AFM 88-19, Chap. 4
are thaw-stable clean sands and gravels, the
Condensation on the floor may result if the relative
construction of a basement which will be kept at above
humidity is sufficiently high. Areas such as kitchens and
freezing temperatures will tend to produce a sump in the
mess halls where high relative humidity can normally be
frozen materials in which thaw water will tend to collect,
expected are more susceptible to condensation than
causing a basement drainage problem.
areas such as warehouses and living quarters. A
(b) Two types of concrete floors are
relatively small amount of insulation properly placed can
reduce these adverse effects significantly.
used in basementless houses: unheated floors relying
(e) Edge insulation for slab-on-grade
for warmth on heat delivered above floor level, and
construction may be installed either horizontally as in
heated floors containing heated pipes, ducts, or other
figure 4-32 or vertically as in figure 4-33 with
integral heating system to constitute a radiant slab (panel
approximately equal results. The flow nets in figures 4-
heating).
Thermal analysis should be made in
32 and 4-33 are theoretical, for assumed steady state
accordance with recommendations contained in the
heat flow conditions, seldom if ever fully realized in the
latest edition of the ASHRAE Guide"'.
(c) Edge insulation for non-radiant
field.
The flow net in figure 4-33 is based on
thermocouple measurements from an actual foundation,
concrete floor slabs on grade may serve the functions of
with some extrapolation. Since footings of slab-on-grade
preventing excessive heat losses at edges of floor slabs,
type buildings in frost areas are normally placed several
maintaining comfortable floor temperatures for building
feet deep in the ground in order to be below the seasonal
occupants, and preventing condensation on floor
frost line, the insulation is easily installed on the foun-
surfaces adjacent to exterior walls.
(d) As shown in figure 4-31, the
maximum rate of heat loss from an uninsulated non-
radiant floor slab occurs at the edge, tending to result in
an uncomfortably cold floor along the building perimeter.
Figure 4-31. Flow net, concrete slab on grade, uninsulated41.
Figure 4-32. Flow net, concrete slab on grade, insulated41.
4-47
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