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Minimum ceiling height

Discussion in 'Residential Building Codes' started by 4thorns, Sep 7, 2017.

  1. 4thorns

    4thorns Bronze Member

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    Hi All.
    Working with IRC 2012
    Please see the code below;

    R304.2 Other rooms. Other habitable rooms shall have a floor

    area of not less than 70 square feet (6.5 m2).

    Exception: Kitchens.

    R304.3 Minimum dimensions. Habitable rooms shall not be

    less than 7 feet (2134 mm) in any horizontal dimension.

    R304.4 Height effect on room area. Portions of a room with a

    sloping ceiling measuring less than 5 feet (1524 mm) or a furred

    ceiling measuring less than 7 feet (2134 mm) from the finished

    floor to the finished ceiling shall not be considered as contributing

    to the minimum required habitable area for that room.

    R305.1 Minimum height. Habitable space, hallways, bathrooms,

    toilet rooms, laundry rooms and portions of basements

    containing these spaces shall have a ceiling height of not less

    than 7 feet (2134 mm).

    1. For rooms with sloped ceilings, at least 50 percent of

    the required floor area of the room must have a ceiling

    height of at least 7 feet (2134 mm) and no portion of

    the required floor area may have a ceiling height of

    less than 5 feet (1524 mm).
    ________________________________________________________

    Does this code mean that the "required floor area" under a Cape style (duel slope) ceiling is the area between the 5' ceilings? For example, if I have 12' between 5' ceiling heights then do I need a minimum of an area 6' wide that has a ceiling height of 7'?

    Any help with the exact interpretation of this piece of code would be appreciated.

    Thanks,

    Doug
     
  2. cda

    cda Sawhorse

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    Rhttp://evstudio.com/how-low-can-you-go-ceiling-heights-in-the-building-code/

    Can you link a diagram of what you are asking
     
  3. cda

    cda Sawhorse

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  4. Francis Vineyard

    Francis Vineyard Sawhorse

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    Doug, you're example would work.

    At minimum 7 ft. is required between the 5 ft. ceiling height.

    Another example where a steeple type roof line having a ceiling height of 7 ft., one ft. wide and 35 ft. in length with the remainder of the ceiling not less than 5 ft. over 35 ft. of floor will satisfy the 70 sf minimum.
     
  5. fatboy

    fatboy Administrator

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    Simplifying Francis' explanation, to count towards the 70 sf minimum, 50%, or 35 sf, must be the full 7', the remaining 50%, 35 sf may be between 7' and 5' in height.
     
  6. 4thorns

    4thorns Bronze Member

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    Thanks for the replies.

    So essentially it comes down to the minimum square footage of 70'?

    Doug
     
  7. 4thorns

    4thorns Bronze Member

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    Too much going on here Fatboy. Got that one in before my question. I'm going to take that as a yes. Basically I was trying to figure out if it was that or if the requirement was half the width between the the 5' ceiling heights had to be 7'.

    Doug
     
  8. 4thorns

    4thorns Bronze Member

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    Is it just me or do several parts of the code seem a bit cryptic?
     
  9. Francis Vineyard

    Francis Vineyard Sawhorse

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    Cryptic as the formula for EERO to have a minimum opening of 20 x 24 inches (W x H) to provide a 5 or 5.7 sf opening.
     
    #9 Francis Vineyard, Sep 8, 2017
    Last edited: Sep 8, 2017
  10. steveray

    steveray Sawhorse

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    "Other habitable rooms shall have a floor

    area of not less than 70 square feet"

    Required to be 70SF....AS FB said, reductions come off the "required" area.
     
  11. steveray

    steveray Sawhorse

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    Funny thing is we got rid of "typical projections" in the main house in the 2012 IRC, so now anything below 7' is technically a violation unless you apply the above section ( lights, headers,soffits,etc.) unless they are "sloped".....

    R305.1 Minimum height. Habitable space, hallways, bathrooms,
    toilet rooms, laundry rooms and portions of basements
    containing these spaces shall have a ceiling height of
    not less than 7 feet (2134 mm).
    Exceptions:
    1. For rooms with sloped ceilings, at least 50 percent of
    the required floor area of the room must have a ceiling
    height of at least 7 feet (2134 mm) and no portion
    of the required floor area may have a ceiling
    height of less than 5 feet (1524 mm).
    2. Bathrooms shall have a minimum ceiling height of 6
    feet 8 inches (2032 mm) at the center of the front
    clearance area for fixtures as shown in Figure
    R307.1. The ceiling height above fixtures shall be
    such that the fixture is capable of being used for its
    intended purpose. A shower or tub equipped with a
    showerhead shall have a minimum ceiling height of
    6 feet 8 inches (2032 mm) above a minimum area 30
    inches (762 mm) by 30 inches (762 mm) at the
    showerhead.
    R305.1.1 Basements. Portions of basements that do not
    contain habitable space, hallways, bathrooms, toilet
    rooms and laundry rooms shall have a ceiling height of not
    less than 6 feet 8 inches (2032 mm).
    Exception: Beams, girders, ducts or other obstructions
    may project to within 6 feet 4 inches (1931 mm) of the
    finished floor.
     
  12. Desert Dweller

    Desert Dweller New Member

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  13. fatboy

    fatboy Administrator

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    Welcome Desert Dweller!

    What code are you working in? Where are you located?
     
  14. cda

    cda Sawhorse

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    Welcome

    Looks like you are in the shake and Bake State,

    Which has taken on a new meaning
     
    Desert Dweller likes this.
  15. Desert Dweller

    Desert Dweller New Member

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    California, thanks.
     
  16. fatboy

    fatboy Administrator

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    Surely CA folks will chime in here........CA codes are not in my wheelhouse........good luck!
     
    Desert Dweller likes this.
  17. Desert Dweller

    Desert Dweller New Member

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    Just had an email exchange with Douglas Hansen, of Code Check fame. I am SO grateful for those "Code Check" books. He confirmed that it is what it is: 7'0" is the bottom of ceiling, and no other intrusion exceptions. Bummer for my design, but at least I know the deal is the deal. Thanks for all your help!
     

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