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

REQUIREMENTS OF AN INSULATION 177
ries that manufacture corklDoard in the United States. Con-
sequently, pure corkboard <strong>insulation</strong> is almost as easily ob-
tained in this country as is any approved building material
in common use ; and considering its permanent insulating
worth and general utility, is fairly priced and often to be had
at a- cost that makes its purchase an unusually attractive
investment.
88.—Permanent Insulating Efficiency.—Thus it will be
noted that the requirements of a satisfactory <strong>insulation</strong> for
cold storage temperatures cover a wide range indeed, and
may be summed up briefly in the statement that such insula-
tion must be of such permanent thermal resistivity, obtainable
in such form, structurally suitable in such degree, readily
available in such quantity and at such price, as to make tliat
insulating material one of permanent insulating worth and
efficiency.
There are, perhaps, a numl^er of insulating materials of
various kinds and in various forms, that show, under labora-
tory tests, when such materials are new and dry and unused,
a heat resistivity, or an insulating value, as high as, or higher
than, pure corkboard <strong>insulation</strong> ; but for many years it has
been the actual experience of countless <strong>insulation</strong> users that
pure corkboard of proper thickness applied in the proper
manner is the only cold storage <strong>insulation</strong> for which, from
every consideration, permanent efficiency can be claimed.