Jim Gardner Construction

Drainage Systems

Most older residences in this area have no perimeter drainage systems. We install dual drainage systems, consisting of a French drain (sub-drain) to collect subterranean water, and a surface drain to collect roof water from the downspouts.

All water is brought to the street either by gravity or through a sump pump if the slope is not sufficient. The sub drain often has to be quite deep to be effective - the drain in the center picture is approximately 6' deep.


We are often installing drainage systems and replacing foundations concurrently. At this residence in the Fruitvale district in Oakland, an improperly installed drainage system caused the north side of the home to settle. We did foundation work, repaired dry rot and stucco, and installed a new, more appropriate drainage system.

In this extreme circumstance, we needed to
excavate 11' below grade to protect some
very tall basement retaining walls which
were leaking by installing a French drain
(subdrain) in front of them.