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Positive Drain for Crawlspace

Discussion in 'Residential Foundation Codes' started by PositiveDrain, Nov 2, 2016.

  1. PositiveDrain

    PositiveDrain Registered User

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    I need help understand the definition and intended purpose of Positive Drain for Crawl space as it is outlined in the Building Code (specifically for Wake County, NC).

    Is the definition/purpose of a Positive Drain for crawl spaces contained in the building code?
    What is a Positive Drain (according to the building code)?
    What is the intended purpose of a Positive Drain (according to the building code)?

    BTW, the house was built and sold in April 2014.

    Thanks, Troy
     
  2. FLSTF01

    FLSTF01 Sawhorse

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    What code and section, please?
     
  3. Rick18071

    Rick18071 Sawhorse

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    No definition in the 2009 IBC or IPC
     
  4. JCraver

    JCraver Sawhorse

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    Hi Troy. Welcome.

    No definition for any kind of "Positive Drain" in the (2009) IRC. Below is all you're going to get, and it doesn't even apply if your crawlspace doesn't have any usable, habitable space:

    R405.1 Concrete or masonry foundations. Drains shall be
    provided around all concrete or masonry foundations that
    retain earth and enclose habitable or usable spaces located
    below grade. Drainage tiles, gravel or crushed stone drains,
    perforated pipe or other approved systems or materials shall be
    installed at or below the area to be protected and shall discharge
    by gravity or mechanical means into an approved drainage sys-
    tem. Gravel or crushed stone drains shall extend at least 1 foot
    (305 mm) beyond the outside edge of the footing and 6 inches
    (152 mm) above the top of the footing and be covered with an
    approved filter membrane material. The top of open joints of
    drain tiles shall be protected with strips of building paper, and
    the drainage tiles 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 tile joint opening or perforation
    and covered with not less than 6 inches (152 mm) of the
    same material.
    Exception: A drainage system is not required when the
    foundation is installed on well-drained ground or
    sand-gravel mixture soils according to the Unified Soil
    Classification System, Group I Soils, as detailed in Table
    R405.1.


    You may have local amendments/additions to the code that define the term you're looking for; best bet would be to ask your Building Official.

    What's the problem you're trying to solve? Is the building dept. asking you to add something, or fix something, or what?
     
  5. PositiveDrain

    PositiveDrain Registered User

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    Thanks, Good info.

    I hope I can describe this correctly.

    The back wall of the house is saturated with water and very muddy and the water is working is way down to the positive drain on the lower side of the house. Additionally, the path the water travels (via capillary action) in the crawlspace is muddy and soft. Other sections of the crawl space are hard and in much better condition.

    I have had someone state that the purpose of a positive drain is to allow water to escape out of the crawlspace if a water lines was to bust. The positive drain is not intended to be used continuously for draining water that gets into the crawl space. For obvious reasons, it is beneficial to keep the moisture level low.

    So that would lead me to my next question of how best to keep water from getting into the crawl space and keep the crawl space dry enough to prevent problems or damage associated with a wet crawl space.

    This product solution look interesting (DELTA Premium Moisture Protection System):
    Now I understand that the DELTA system is design for basements, but I believe it is important to keep crawl spaces just as dry and clean as possible.
     
  6. Francis Vineyard

    Francis Vineyard Sawhorse

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    NC may have amended this section; check with your AHJ. Assuming this not a conditioned (unvented) crawl space;

    R408.6 Finished grade. The finished grade of under-floor surface may be located at the bottom of the footings; however, where there is evidence that the groundwater table can rise to within 6 inches (152 mm) of the finished floor at the building perimeter or where there is evidence that the surface water does not readily drain from the building site, the grade in the under-floor space shall be as high as the outside finished grade, unless an approved drainage system is provided.

    Postscript what does the exterior grade look like; does it allow surface water to drain away from the foundation?
    Sometimes the backfill will settle around the foundation and allow water to pond.
    How about the rain gutter down spout discharge?
    Are plantings being watered nearby?
     
    #6 Francis Vineyard, Nov 2, 2016
    Last edited: Nov 2, 2016
  7. PositiveDrain

    PositiveDrain Registered User

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    First, I have done nothing to the landscaping, etc since we purchase the house and I wanted to get this nut cracked before doing anything that would alter the original state or cause additional problems.

    The grade is pretty good (not level). The water flows from the Right-Rear corner of the lot to the Left-Front side of the lot. The fall/drop from that Left-Front Corner of the house to the curb might be close/tight/tricky. But sometimes the grade can fool the eye and would need to actually measure it to make sure all is kosher.

    I do not see any ponding around the foundation except in one place along the rear of the house. The builder did try to resolve this by grading the path for the water to move away from the house. But the ponding still occurs.

    The builder did come back and installed piping from the gutters of the house to the road. The builder did the same for all my neighbors as well. The house sit about 6-7 feet apart (very close). The builder also ran all HVAC condensate lines into drain pipe that discharges to the curb.

    There is minimal planting around the house and there is no irrigation or watering of the plants.

    Thanks,
     

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