Figure 7-1.Proper drainage for storm water.
float-controlled electric pump. Drain tiles should
generally be pitched from a high point around the
perimeter of the building to a low point below the floor
slab where the sump and pump are located. Where roof
drainage causes a foundation water problem, gutters
and downspouts should be installed, preferably
connected to a storm sewer. Gutters that are
improperly hung or allowed to become clogged will
overflow and lose their effectiveness. Leaks in gutters
should be repaired promptly. Splash blocks or drain
tiles should be installed in the absence of storm sewer
connections to prevent pooling of water below
downspouts. The drainage of surface water toward a
building can be reversed by sloping the ground surface
away from the foundation wall. Where that is not
possible, ditching or installing drain tiles will serve the
same purpose. The general grade of crawl spaces
should not be lower than the surrounding area that
should be graded to drain away from the building.
Foundations are subject to deterioration whether
from material or construction deficiencies or from
environmental conditions. The deterioration of
foundation materials must be observed directly unless
the effects are severe enough to cause foundation
settling. Excessive moisture from surface or
subsurface sources is a major cause of timber
deterioration, providing the necessary condition for
wood decay and encouraging insect infestation.
Improperly seasoned wood is subject to cracking,
splitting, and deflection. Concrete and masonry are
subject to cracking, spalling, and settling, particularly
under adverse ground and climatic conditions. Steel
and other ferrous metals are subject to corrosion in the
presence of moisture and sometimes by contact with
acid-bearing soils. Signs of corrosion are darkening,
rusting, and pitting of the metal.
Corrective actions taken to alleviate the
deterioration of the foundation materials given above
are covered in detail later in this chapter in the section
dealing with the maintenance and repair of waterfront
Considerable deterioration extending from the
foundation to the building superstructure can be
caused by neglect of crawl spaces, especially in
climates where it is necessary to enclose the space to
maintain comfortable floor temperatures.
Unventilated crawl spaces contribute materially to
rapid absorption of moisture into structural wood and
other materials, and the spaces soon become a natural
habitat for fungus growth and termites. Sills, joints,
and subflooring may be affected by wood decay.
Condensation may occur in the studding spaces above
the floor level and cause paint failures.
Crawl spaces should be carefully checked
periodically. In checking these spaces, ensure that they
are clean, clear, and accessible. An accumulation of
rubbish in the space may provide a natural harbor for
insects and rodents as well as impede access and
possibly interfere with drainage. Scrap wood is a clear
invitation to termites.
Look for disorganized storing of any material in
crawl spaces. Also, check for accumulations of water
that may breed mosquitoes, cause fungus growth, and
weaken soil bearing under footings.
Ensure that all ventilation openings are covered
with suitable hardware cloth or copper screening to
prevent entry of birds and rodents. In addition, see that
access doors to crawl spaces are provided with a
suitable padlock and kept closed.