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Crawlspace dampproofing.

Discussion in 'Residential Foundation Codes' started by Buelligan, Feb 8, 2017.

  1. Buelligan

    Buelligan Sawhorse

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    Ok just a quick question. Does the code require dampproofing a crawlspace that is NOT conditioned?

    R406.1 Concrete and masonry foundation dampproofing.
    Except where required by Section R406.2 to be waterproofed, foundation walls that retain earth and enclose interior spaces and floors below grade shall be dampproofed from the higher of (a) the top of the footing or (b) 6 inches (152 mm) below the top of the basement floor, to the finished grade.

    "enclose interior spaces and floors below grade"
    This statement for many, excludes crawlspaces from dampproofing because of no floor in the crawl.

    The confusion seems to be the use of "interior space" without a definition. Would an unconditioned crawl be considered an "interior space"?

    I personally read that as the crawl space would require ALL 3 conditions, enclose earth AND interior spaces AND floors, they are not separated by OR.

    Now with that said I personally do believe that it is a fantastic idea in most cases, the less moisture anywhere the better, but as an inspector I can't make someone do it.
     
  2. FLSTF01

    FLSTF01 Sawhorse

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    I agree that while certainly best practice, 406.1 doesn't require dampproofing for crawlspace walls. I think I could justify mandating they do it if it were a case where there was an addition with a crawlspace and an opening into the existing full basement.
     
  3. Buelligan

    Buelligan Sawhorse

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    Gee 23 views and no comments? Why so quiet? You guys always have an opinion! LOL ;)
     
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  4. Paul Sweet

    Paul Sweet Sawhorse

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    We're often quiet when we agree. It gets a little noisy when people disagree!
     
  5. mark handler

    mark handler Sawhorse

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    Is a Crawl Space, enclosed, Yes.
    Is it Interior Space, Maybe, or is it an exterior enclosed space?
    With ventilation, I conceder it Exterior space.
    With ventilation, No Vapor barrier required, in my climate zone.
     
  6. linnrg

    linnrg Sawhorse

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    So a few years ago some areas nearby began experiencing higher than usual groundwater. As a consequence there were many crawl spaces that now had active water in them. People experienced many problems including having to relocate because it also flooded septic systems and in some instances surface flooding occurred preventing people from getting to the buildings. The area was previously high and dry. Oldtimers said it was a regular occurring event that water tables can rise up so dramatically, others pressed that new development and roads changing existing drainage patterns were the cause. Some people simply walked away from the homes because they could not rebuild septics or other reasons.
    So following that, even though these areas were outside of my jurisdiction, I get the flood (he he!) of calls wanting to know why we did not require every crawl space foundation to be "waterproofed" (not just "damp proofed") . Real estate transactions usually get private home inspectors and those inspectors were now writing that up. The people were really now affected because they could not sell their homes. I seem to recall talk of disaster declaration.
    So our average soils had fairly decent drainage an if the drainage around the building complies with the 6" from wood to soil and the 6" in 10' slope rules you normally have little to no foundation water. Roof gutters are also a big part of the solution.
    My own personal home on a reinforce masonry crawl space has a metal roof so during the heavier snow years I can get a large pile of snow near the foundation. Spring breakup has let some water in but not in significant quantities. I have a vapor barrier. I do not have damp proofing. I have an other home next door that has a basement and I have to have an interior drain and sump pump for groundwater that runs a couple of weeks a year. Frost heave can change my drainage patterns some. Some years the breakup goes out fast and water flows away other years it is slow an new ice buildups along with the slow melts are the ones to watch for

    The way the past codes were written it was possibly required in areas that have know soils or other indicators, I think now in the newer section R406 (2012) I believe it to be required. The "water proofing is now where some circumstances may dictate that versus damp proofing.
     
  7. JBI

    JBI Sawhorse

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    The IRC is all over the place with this one.
    For instance R406.4, Pre-cast foundation system dampproofing, specifically states '... enclosing habitable or usable spaces located below grade...'.

    IF there are enclosing walls then the 'under-floor space' (as regulated for ventilation in R408) would require damp or water-proofing IMHO. Lots of crawl spaces have equipment within.
    Also where do you draw the line? Anything with less than 'required ceiling height' is deemed 'under-floor space' or more commonly 'crawl space' even though most adults can stand up in there.

    If there are no enclosing walls, I'd agree with mark handler's comment above that it is 'exterior'.
     
    linnrg likes this.
  8. Francis Vineyard

    Francis Vineyard Sawhorse

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    Although it may be good practice in my opinion R408.6 implies under-floor or crawl spaces with covered ground (earth) do not require dampproofing unless there's a slab or wood floor as prescribed in the code.

    However a drain tile is required for usable spaces e.g. equipment and appliances (Ref. R405.1).
     
  9. ADAguy

    ADAguy Sawhorse

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    Its important to note that where dampproofing of crawl spaces is provided that adequate air circulation must still be maintained to prevent the buildup of mold and possible methane/radon containment.
     
  10. Buelligan

    Buelligan Sawhorse

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    Thanks for that answer, but I was not asking about VAPOR BARRIER inside the crawl space. I am curious if any one requires dampproofing ( i.e. Bituminous coating or other approved methods) on the exterior of crawl space walls. What does one consider "usable space"?
     
  11. steveray

    steveray Sawhorse

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    If there is equipment, if it seems like it is likely to become a storage area....I try to have a discussion with the homeowner and if they absolutely don't want to do it, I will mark the plans or permit or CO with "Not to be used for storage" or whatever sounds good at the time....
     
  12. linnrg

    linnrg Sawhorse

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    I certainly use my crawl space for storage. Most homes I have been into that are on crawl spaces use them as such. The only ones that do not are the ones at very minimum dimensions (clearance from wood to soil).
    Buelligan, I have began to require the "damp proofing". That said though then it comes up what do I want to which I reply why not go all the way with waterproofing.

    The code for this topic is very much up to local conditions. Then there is the struggle of flashing
     
  13. JonS

    JonS Registered User

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    Here's my take. I'm the home owner who is paying a general contractor to build a house on my lot that I own outright. I'm the guy who reads the code book and watches everything.

    406.1 and 406.2 use the phrase "interior spaces and floors" when you get to 406.3 it switches to "habitable or useable spaces"

    Interior spaces and floors is specifically called out different than habitable or useable.
    The crawl space doesn't have to be habitable or useable to be considered interior, all it has to be is within the limiting boundaries, which it is.
     
  14. ADAguy

    ADAguy Sawhorse

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    Consider that many houses constructed on descending slopes in mountain fire districts often have enclosed crawl spaces large enough to be partly enclosed on the highest end, the lowest side becoming occupiable and the space behind (crawl space) requiring dampproffing, or not? Cross ventilation of the enclosed crawl space must be maintained but is often obstructed by the new habitable space.
    Roof water on these houses must be drained up to the street by sump pump if no drainage easement to lower street exisits. Water allowed to collect in rear yard with no drain can lead to settlement of footings and downslope creep.
     

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