Evening star. [volume] (Washington, D.C.) 1854-1972, 1889-04-04
WALLS MUST BE POROUS.
Some Interesting Points From Professor
Faya on the Sanitation of Dwellings.

The walls of lecture room II of the Column
bian university were peculiarly decorated last
night. They were covered with huge diagrams
ascending from the floor to half the height of the
room. and representing all the most remote
places in a dwelling, as we'll as other ones more
interesting from the point of view of Lenten
stomach-kitchens and pantries. They all
showed sections with the runs of the principal
drain pipes, and blue and black arrows, evil
IDENTIFY intended to show the currents of good
and bad air, striped Enthusiastically through the
openings of doors, out of pipes and down into
the frying pans, and into other similar places
where you least desired to see them.
These diagrams were destined to illustrate
the lecture of Professor Fava on Sanitary SCI
ence." this lecture being the third in the series
delivered to the advanced students of the
school Of civil engineering, and which, by
courtesy OF the president of the faculty, has
been opened to the public.
DAMP WALLS.
The subject of the evening was the SANTA
ton of dwellings. Prof. Fava proceeded to
prove that what we commonly understand as
damp walls" is the product of two defects
equally avoidable as well ON the part of the
professional expert engaged on the work as on
the part of the public. If the site of a home,
ground, on wet subsoil, then many precau-
tions must be taken, the neglect of which is
paid dearly by the loss of health and of life
of the indwellers. solid. deep foundation of
lmpervious material is required. An air space
around and beneath the house must be pro-
vided, the space around the house being filed
In, after the drying of the foundation walls.
with loose material. allowing the drainage of
the surface water into stratum below the found
alton walls: If the subsoil itself is impervious
like clay, then artificial under-drainage should
be established. If any one of these rules is
neglected as the walls themselves are porous
they will suck in the water through capillarity
as piece of sugar does when held with one
end into cup of coffee. and the whole wall
will be continuously wet. The sanitary laws
should be made to reach the professional man
allowing building to go up without the neces-
walls
Another reason which makes wall damp is
the fact OF moving into new building when
the walls have not had time to dry. As soon
as we move into a house we create moisture
therein, and if the wall is not dry enough in
advance to be able to absorb this moisture, and
give 1t partly out into the outer air. according
to how the atmospheric conditions may be, then
the circular process of condensation and evap-
Grafton inside of the room will take place.
Walls, Prof. Fava says, must be porous. They
must have the faculty of absorbing water
and giving 1t out again. Impervious walls
such as are made out of slags in smelling
districts, or entirely of glass, as is some
times suggested, would be fallacy
unless they are of such dimensions as to con-
tain much greater quantity of air than an
ordinary house can contain. As they do not
allow any Initiated air to pass through the walls
they retain in the room all noxous gases pro-
duced by the in-dwellers through respiration
and perspiration. the vapor produced by the
water used in washing and cleansing, and the
exhalations from the different waste-pipes.
A FEW SIMPLE PRINCIPLES.
Prof. Fava deduced the following as a few
simple principles: Dry walls are requisites for
health, damp walls are causes of disease. A
wall is dry when it has ventilation on both
sides and air in the very middle of its bricks
and mortar. Porous substances are necessary
to secure good wall ventilation. A dry wall
allows air to pass through, thus fostering the
change of atmosphere in the room. Damp
walls prevent this passage. house should
never be occupied before its walls are salts
factorily dry. A house occupied against this
rule is, on account of the humidity created in
1t by the inhabitants, prevented forever from
drying. Walls built on dry foundation and
exposed to the motion of the air will dry. ac-
cording to the months of wind or quiet, more
or less rapidly on an average, in three four
months after plasterlng Internal heat, pro-
duced by stoves, fires gas. &C.. causes motion
of the air. Appliances for producing heat
with their pipes and fues are therefore good
ventilators. Porous walls evaporate greatly
from the external surface, where they are con-
stantly swept by air in motion, while walls
made of impervious material cannot let out the
humidity deposited on their inner surface. If
walls are sufficiently dry before the house is in
habited the humidity of the atmosphere of the
rooms is never sufficient to saturate them
thoroughly, and comparative dryness of the
dwelling is insured i'll all cases. maintaining a
healthful atmosphere therein. Chimneys. doors,
and windows are good ventiators, and the best
ventiator in the house is the hall. 1t is there
fore mistake to make halls so narrow that two
people can hardly pass at the same time, ex-
cept when the narrOwness of the building lot
does not allow otherwise