Figure 17. General view of roof D4 looking towards downtown Dallas (i.e., about
southeast).
(1/4-in.- [6-mm-] thick) layer of frozen fibrous
ROOF D4
glass insulation was present on the concrete deck,
This roof consists of a ballasted EPDM mem-
but the rest of the insulation was dry. When cut C
brane, expanded polystyrene insulation (2 in.), an
was taken, we noticed that there was a lot of frost
old bituminous built-up membrane, fibrous glass
in the fibrous glass near an insulation seam but
insulation (7 in.), and a concrete deck. The tem-
little frost in the middle of the insulation board.
perature of the freezer below this roof was 0F. A
Finding frost, not ice, suggests that moist outdoor
general view of this roof is shown in Figure 17.
air infiltrating into the freezer in this area has de-
There were no bright or dark thermal anomalies
posited some of its moisture within the insulation.
on it. However, the infrared survey done within
Some moisture has also entered the freezer and
the freezer revealed extra brightness within a few
has frosted the roofwall intersection in this area,
feet (about a meter) of the northeast corner of this
similar to that shown in Figure 11.
roof. That brightness was similar to that shown
for roof D1 in Figure 11. We expect that it was
caused by air infiltration not wet insulation. Core
ROOF D5
4 and cut C were taken in this area to verify our
suspicions. Core 4 findings are presented in Table
This roof consists of a ballasted Hypalon mem-
6 and cut C findings in Table 7. At core 4, a thin
brane, a thin slip sheet, a thin, old mineral sur-
Table 6. Core sample findings for roof D4.
Moisture
content
Thickness
(% of
TRR
Core
Insulation
(in.)
dry weight)
(%)
Status
4
EPS
2
1
100
dry
4
FGL
2
0
100
dry
4
FGL
2.5
0
100
dry
4
FGL
1.75
0
100
dry
4
FGL(frozen)
0.25
357
20
WET
15
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