HomeMy WebLinkAboutFOUNDATION DRAINAGE - 05-00021 - 624 Centennial Loop - New SFRIrk
FOUNDATION DRAINAGE
Section 40S of the 2000 Intemational Residential Code requires that drains shall
bc provided around foundations. The r"I�'y OF REXBURG B����ng Department and the
City Engineer have decided not to enforce this rude.
Almost all bu'ld.ng Tots located off of the hill and dawn 1"n the valley have a so1*1
structure, which consists Of topsoil over gravel Section 405 of the code includes an
exception for well -drained sons. Lois on the hill are another subject altogether. They are
almost entirely comprised of silt over bedrock. Foundation drainage could be very
beneficial for most of these lots. Many houses on the hill have part of their foundations
bearing directly on the bedrock. As water seeps into the soil {especially in spring} it fiends
to drain downhill along the bedrock. Some foundations acting as a dam,divert the flow of
water around them. This lends the homy toossiblepwater damage �n the hasemen�.
Foundation drains as caped for in the International Code should be installed at
properties that match the descriptions given above. We will allow the contractors and
developers to make this Judgment call. Included below is tie code covering this issue?
SECTION R405
FOUNDATION DRAINAGE
R405.1 -Concrete or masonry #'ounaahons. Drains shall be
provided around all concrete or masonry foundations that re-
tain earth and enclose habitable or usable spaces located below
grade. Drainage tiles, gravel or gushed stone drams, orated
pipe or other approved systems or materials shah be installed at
or below the area to be protected and shall discharge bvgravity
o�-mechanical means into an approved drainage system. Gravel
or crushed stone drains shah extend at least I foot (305 mm)
beyond the outside edge of the footing and b inches (153 mm)
above the top of the footing and be covered with an approved
filter membrane material. The top of open joints of drain tiles
shad be protected with strips of building paper, and the drain-
age tides or perforated pipe shall be placed- on a minimum of
2 inches (51 mm) of washed gravel or crushed rock at least one
sieve size larger than the dile joint opening ar perfaration and
covered with not Tess than 6 inches (153 mm) of the same
material.
Exception: A drainage system as not required when the
foundation is installed on well -drained ground or sand-
gravel mixture soils according to the Unified Soil Classifica-
tion System, Group I Sails, as detailed in Table R405. 1.
8445,2 Wood foundations. Wood foundations enclosing hab-
itable or usable spaces located below grade sham be adequately
drained in accordance with Sections R405.2.1 thrvubh
R4Q5.�.3.
R405,2.1 Base. A porous layer of gravel, crushed stone or
coarse sand shall be placed to a minimum thickntss of
4 inches (1 02 mm} under the basement. floor. Provision shall
be made for automatic draining of this layer and the gravel or
crushed stone wail footings.
R405.2*2 Moisture barrier. A 6 -mil -thick (4. 15 mm) poIy-
ethylene moisture barrier shalt be applied over the porous
layer with the basement floor constructed over the poIy-
ethylene,
R405a2.3 Drainage system. In other than Group I soils, a
sump shall be provided to drain the porous layer and foot-
ings. The sump sham he at least 24 inches (f 10 mom) in dia-
meter or 20 inches square (0. 0 129 m2), shah extend at feast
24 inches (6 14? mm) bel ow the bottomof the basement fl oor
and shah be capable of positive gravity or mechanical drain-
age to remove any accumulated water_ The drainage system
shah discharge into an approved sewer system or to daylight.
24WINTERNATIONAL RESIDENTIAL CODES