ers), the rapid growth of wet insulation makes it
FINDINGS AND RECOMMENDATIONS
somewhat ill-suited for use in freezers and cool-
A number of roof-specific findings and recom-
ers where vapor drive and air movement are both
mendations are presented in the body of this re-
usually inward.
port where each roof is discussed. Visually, these
We found wet expanded polystyrene (EPS) in-
roofs appear to be in good condition, but thermo-
sulation in two roofs (D7 and A3) that had not been
graphically, eight of the ten are suffering some
re-covered with a new waterproofing membrane.
moisture related problems.
Additional investigations are needed to determine
On-the-roof infrared roof moisture surveys
the total amount of wet EPS in each roof. We know
were found to be more informative than indoor
of no way to dry out that insulation, in place, even
infrared roof moisture surveys because shelving,
by warming up the freezers below.
goods, piping, and such, block indoor views of the
In four of the roofs, EPS insulation was placed
roof. Nonetheless, the indoor infrared surveys and
over the old bituminous membrane in conjunction
indoor visual inspections were quite valuable
with adding a new EPDM waterproofing mem-
supplements to the on-the-roof surveys and in-
brane above. In one and perhaps two of those
spections. The indoor work showed us that air
roofs, some of that "new" EPS insulation has be-
infiltration is occurring at places along roofwall
come wet. Flaws in the flashings and membrane
intersections.
of the new EPDM waterproofing system allowed
Air infiltration at these intersections is appar-
water to gain access to that insulation. Fortunately,
ently bringing moisture into the roofs and into the
only a small portion of that insulation is wet but,
freezers themselves. Permeable fibrous glass in-
unfortunately, there is no way to dry out that ma-
sulation does not resist air infiltration very well,
terial in place.
and thus of all the insulations encountered, it is
Roof D6 (one of the two problem-free roofs in
the most susceptible to moisture gain by air move-
this study) contains EPS insulation and it is dry.
ment.
The new waterproofing membrane on this roof
The adverse effects of air infiltration on the per-
suggests that some problems occurred in the past.
formance of roofs of freezers and coolers deserves
Perhaps past moisture has thawed and drained
further study.
away during defrosting of this freezer. Perhaps,
We found more wet insulation in these roofs
deep in this roof, some moisture still exists that
than we expected. Eight of the ten contain some
we were unable to detect. Perhaps the new water-
wet insulation and therefore have lost a portion
proofing membrane was not needed.
of their insulating ability. Fortunately, only a por-
Roof A1 (the other problem-free roof in this
tion of each roof, not the entire roof, contains wet
study) contained extruded polystyrene and
insulation, except for D7, all of which may con-
isocyanurate insulation. The watertight EPDM
tain wet insulation. Unfortunately in most cases,
membrane, not these insulations, deserve the
cost-effective, easy, reliable ways of removing this
credit for that.
moisture are not available. Knowing that, we feel
Roof A3 has wet EPS insulation and a badly
it is wise to select more moisture resistant insula-
rusted steel deck that should be examined in detail.
tions for such roofs.
Roof A2 contains wet phenolic insulation that
Some of the moisture we found was in the "old"
is capable of destroying a warm steel deck in a
insulation of roofs that have been re-covered with
few months. Since the A2 steel deck is cold, its rate
a new waterproofing membrane without remov-
of deterioration is slow but it is progressing. Plans
ing wet insulation. We found areas of wet fibrous
should be made to remove the phenolic insula-
glass insulation in roofs D1, D2, D4, and D5. We
tion from this roof.
expect that a small amount is present in roof D3
As long as the roof membrane and its flashings
also. It is likely that flaws in the original bitumi-
keep water and moist air away from the insula-
nous built-up membrane allowed water to enter
tion in roofs of freezers and coolers, any insula-
the "old" fibrous glass insulation. It was easy for
tion will stay dry and perform well.
that water to move laterally in that material. As a
Most freezers and coolers are subjected to in-
result, cancers of wet fibrous glass insulation re-
tense inward vapor drive and air infiltration for
main in those roofs. Some of that moisture is in
their entire lives. If a permeable insulation such
the form of ice. While fibrous glass insulation may
as fibrous glass is to be used, it is most important
be able to be dried out (by warming up the freez-
to seal the roof against air infiltration.
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