Storage space with concrete floors

Mark Ast poses a question on moisture in relation to concrete
floors, and although I'm not a buildings expert I could add a few
facts that are commonly known in Sweden as a lot of houses built
here in the last 30 years suffer from moisture problems in
correlation with concrete.

    1.  Concrete can absorb a lot of moisture and even water.

    2.  You should be very attentive as to where the source of
        moisture comes from. The most severe problems come from
        improper isolation under the floor( assuming that it lies
        directly on the ground) in connection with ground water
        levels  rising during wet periods of the year and bad
        drainage systems. The moisture will then diffuse through the
        floor.

    3.  If such a floor is covered with an impervious material like
        plastic you will risk having both mold and bacterial damage
        as the water cannot evaporate.This will perhaps not
        immediately destroy the books but the building will suffer
        damage and the indoor climate becomes dangerous to your
        health.

    4.  Small leaks from a water pipe can " fill up" a concrete
        floor and cause severe problems.

My recommendation is that you concentrate on finding eventual
sources for moisture or water and evaluate the risks according to
this, and you should of course also measure the relative humidity
levels during the year.

Per Cullhed

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                  Conservation DistList Instance 10:4
                   Distributed: Friday, June 28, 1996
                        Message Id: cdl-10-4-009
                                  ***