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Another Habitalbe Attic Question

Francis Vineyard

Francis Vineyard

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Jan 1, 2010
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Location
Charlottesville, VA
Architect uses the term "loft" and I would describe it as a flat roof above the third story, half the span is a full width shed dormer, none of its rafters on top of the third story top plate. What point does this become a 4th story?

2009 IRC.

Thanks in advance

Francis
 
Does it have a code compliant stairway?

Will the ceiling/floor joist support at least a 30PSF live floor load

Does it have code compliant headroom?
 
HEIGHT, STORY. The vertical distance from top to top of two successive tiers of beams or finished floor surfaces; and, for the topmost story, from the top of the floor finish to the top of the ceiling joists or, where there is not a ceiling, to the top of the roof rafters.

R301.3 Story height. Buildings constructed in accordance with these provisions shall be limited to story heights of not more than the following:

1. For wood wall framing, the laterally unsupported bearing wall stud height permitted by Table R602.3(5) plus a height of floor framing not to exceed 16 inches (406 mm).

Exception: For wood framed wall buildings with bracing in accordance with Tables R602.10.1.2(1) and R602.10.1.2(2), the wall stud clear height used to determine the maximum permitted story height may be increased to 12 feet (3658 mm) without requiring an engineered design for the building wind and seismic force resisting systems provided that the length of bracing required by Table R602.10.1.2(1) is increased by multiplying by a factor of 1.10 and the length of bracing required by Table R602.10.1.2(2) is increased by multiplying by a factor of 1.20. Wall studs are still subject to the requirements of this section.

2. For steel wall framing, a stud height of 10 feet (3048 mm), plus a height of floor framing not to exceed 16 inches (406 mm).

3. For masonry walls, a maximum bearing wall clear height of 12 feet (3658 mm) plus a height of floor framing not to exceed 16 inches (406 mm).

Exception: An additional 8 feet (2438 mm) is permitted for gable end walls.

4. For insulating concrete form walls, the maximum bearing wall height per story as permitted by Section R611 tables plus a height of floor framing not to exceed 16 inches (406 mm).

5. For structural insulated panel (SIP) walls, the maximum bearing wall height per story as permitted by Section 614 tables shall not exceed 10 feet (3048 mm) plus a height of floor framing not to exceed 16 inches (406 mm).

Individual walls or walls studs shall be permitted to exceed these limits as permitted by Chapter 6 provisions, provided story heights are not exceeded. Floor framing height shall be permitted to exceed these limits provided the story height does not exceed 11 feet 7 inches (3531 mm). An engineered design shall be provided for the wall or wall framing members when they exceed the limits of Chapter 6. Where the story height limits are exceeded, an engineered design shall be provided in accordance with the International Building Code for the overall wind and seismic force resisting systems.

MEZZANINE, LOFT. An intermediate level or levels between the floor and ceiling of any story with an aggregate floor area of not more than one-third of the area of the room or space in which the level or levels are located.

A "loft" would need to be under the ceiling of the story it serves.....
 
ATTIC, HABITABLE. A finished or unfinished area, not considered a story , complying with all of the following requirements:

1. The occupiable floor area is at least 70 square feet (17 m2), in accordance with Section R304,

2. The occupiable floor area has a ceiling height in accordance with Section R305, and

3. The occupiable space is enclosed by the roof assembly above, knee walls (if applicable) on the sides and the floor-ceiling assembly below.

JMHO

I believe the clarification is in #3

If the space has knee wall or sloped wall construction to meet the ceiling height requirements of R305 then it is an attic. If the wall construction is verticle then it is a story.

I personally don't like the habitable attic provison
 
Big Mac design exceeds the minimum; needed to know the threshold when it is a story.

Steveray thanks a million. I was stuck focusing on the fact that a ceiling shall be fastened to the rafters but that may not always be the case.

mtlogcabin this brings up my question below.

Now that I have something to hang my hat on; allow me to propose a question to help find another threshold; with the exceptions of gable dormers the addition of a shed dormer of any size and configeration converts an attic into a floor level?

Dormers.jpg


Francis
 
Last edited by a moderator:
Francis - I would consider any of the sketches you have provided as a story if the floor system provides adequate structural integrity as a floor. I would also wonder, if the difference is whether there are vertical walls or a roof line, what about 'A' frame type structures?
 
The code cannot possibly cover every case. R301.3 the exception is gable end walls up to eight ft. in height above the 3rd floor, guess that could limit the height of the "A" frame.

And it would be okay to have a roof with 4 gable end walls and I'm not sure if it's because the other configurations adds to the load of the studs below attic floor ceiling assembly.

Francis
 
FWIW

One of my replys today to allow dormer windows in hip roofs and townhouses between end units. Note Virginia amended R612.2 height to 18 inches from 24.

"Unfortunately the addition of a dormer window would not comply for the exception of gable end walls in section R301.3 Story Height. Except for gable end walls habitable attics are required to be enclosed by the roof assembly.

I’m reminded that operable skylights and roof windows are available as emergency escape and rescue openings if they meet the size requirements and the bottom of their opening is within 44 inches of the floor below. Careful not to place it closer than 18 inches above the floor or it will need child fall protection."

Thanks and hope this information is useful.

Francis
 
Parsing this out... If I pop out a dormer it is a story. When does a skylight become an eyebrow become a dormer. vertical walls other than the gable ends? Hmm, I can gambrel them. This is reminiscent of the mansard roofs' evolution for tax avoidance.

I cannot exceed 8' at the gabled end wall, 50% of the area above 5' needs to be above 7'. It would almost always be a habitable attic.

For a twist and back to a dark place. I have a "loafing loft" on the present job. The area is just under 7' the gable wall is thus under 7', area is also then below habitable. we have a small non egress window and 18" kneewalls, a reading or grandkids nook. We've gone back and forth. The interp is that is we build stairs they must comply, I don't fully disagree, someone is going to fall asleep up there. I can install a fold up attic stair, pass and we both walk away. The ahj will entertain me or the client designing the pull down stair, hmm there's a can of worms.
 
I realize how this seems confusing; but once a dormer wall; including vertical glazing is allowed for a "habitable attic" then you start writing your own code.

Don't remember where it's in the code that a wall is not more than 60 degrees.

Can have as many gable end walls you can work in and not be a story.

Francis
 
R201.3 Terms defined in other codes.

Where terms are not defined in this code such terms shall have meanings ascribed to them as in other code publications of the International Code Council.

2009 IBC

EXTERIOR WALL. A wall, bearing or nonbearing, that is used as an enclosing wall for a building, other than a fire wall , and that has a slope of 60 degrees (1.05 rad) or greater with the horizontal plane.
 
Is a ship ladder allowed on these mezzanines? If so, can you call it a LOFT MEZZANINE or you can only call/label it STORAGE?
 
hgrimberg said:
Is a ship ladder allowed on these mezzanines? If so, can you call it a LOFT MEZZANINE or you can only call/label it STORAGE?
Click to expand...


Welcome!!!
If you have not been already


You may be one of the longest distance poster we have.

Not sure if Hawaii beats you?? Guess it depends on starting point
 
And if we call it STORAGE, then there is no minimum head height of 7'-0" for at least the 50%, right? it could be whatever height?
 
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