Cork insulation; a complete illustrated textbook on cork insulation ...

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STRUCTURAL SUGGESTIONS 211
effect a general leveling up of the last course of <strong>insulation</strong>
in preperation for the finish over <strong>insulation</strong>. But hot asphalt
between the layers of corkboard is preferable, because it gives
just that much additional air-proofing. Detailed information
relative to asphalts will be found in a later Article in this
Chapter; and detailed specifications and directions for apply-
ing asphalts will be found in their proper order in Chapters
XIII and XIV, respectively.
It must not be inferred that the greater proportion of
moisture in corkboard <strong>insulation</strong> comes in from the outside
through the building construction. It is but one of two ways,
and it will be recalled that the other way in which moisture
finds entrance is through the Portland cement plaster finish
that it has been for so many yea^s the universal custom to
apply ; but the proper preparation of building surfaces to
receive <strong>insulation</strong> is one of the most important single con-
tributing items to the high efficiency and long life of cold
storage room <strong>insulation</strong>.
97.—Insulation of Floors, Columns, Ceilings and Beams.
Probably because a cold storage room is colder at the floor
than at the ceiling, even though the floor <strong>insulation</strong> may be
wholly inadequate, some have been tempted to specify either
very light floor <strong>insulation</strong>, or none at all. The importance of
adequately insulating the bottoms of ice-making tanks and
floors of all ice storage houses and cold storage rooms,
when such floors are located on the ground, is prob-
not as fully appreciated as is the necessity for proper
<strong>insulation</strong> of other surfaces.
The fact that a cold storage room is colder at the floor
:-than at other vertical points, even though it has no <strong>insulation</strong>
on the floor, is due to the weight of cold air as compared with
warm air, rather than to the possibility of the heat leakage
being less through such uninsulated floor than it is through
the insulated walls and ceiling. This fact, of course, is very
elemental ; but it evidently persists in the minds of some, and
should be disposed of before proceeding to the consideration
of the proper <strong>insulation</strong> of all floors that rest on the ground.
The average temperature of the earth varies for different
years and localities between about 50° and 60° F. If a cold
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