Does Drywall Ceiling = Structural Ceiling

jbt260

Member
Location
Ohio
Occupation
Electrical Engineer
I apologize if this has been asked before, but my search could not find a direct answer. Is a drywall ceiling mounted to the bottom of trusses considered structural as it pertains to the dedicated equipment space? There is nothing above the ceiling except insulation and bottom of roof deck.
 

Rock86

Senior Member
Location
new york
Occupation
Electrical Engineer / Electrician
I know this post is almost a year old, but it came up in my office. I say that a gypsum ceiling mounted to joists would be structural, but others disagree. Is there any supporting documentation to answer this topic?
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I agree such a constructed ceiling is structural, while a suspended ceiling is not.

It doesn't need to actually support the building to be structural.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
What's the difference between this ceiling and a suspended Sheetrock ceiling?
Do you mean a solid, finished hanging ceiling or loose drywall panels in a T-bar ceiling grid?

The former, structural; the latter, not. The difference? Physical permanence vs immediate lift-out access.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Do you mean a solid, finished hanging ceiling or loose drywall panels in a T-bar ceiling grid?

The former, structural; the latter, not. The difference? Physical permanence vs immediate lift-out access.
No I'm referring to a finished drywall ceiling that is hung from the structure. Some thing like this drywall T-bar grid system. I'm having a hard time envisioning this as a structural ceiling.

Drywall Grid001.jpg
Drywall Grid002.jpg
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
No I'm referring to a finished drywall ceiling that is hung from the structure. Some thing like this drywall T-bar grid system. I'm having a hard time envisioning this as a structural ceiling.
If the drywall is screwed into the grid from below, mudded into a single slab and mudded where it meets the walls, and no panels lift out, then it's more like than unlike a wood-framed ceiling.

There is nothing that says that a structural ceiling is one on which the building's integrity depends.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
No, hangs like a cloud
See previous post.

Hangs stiff like any framed ceiling, or flexible and easily removed and replaced?

I've seen stores and restaurants with sections of hanging ceiling and sections open to the roof structure.

Those I would not consider structural. They're not necessarily in the way of wiring additions.
 

Rock86

Senior Member
Location
new york
Occupation
Electrical Engineer / Electrician
Clearly this sparked a nerve. I'm guessing there is no clear definition? I would consider the grid type that infinity mentioned to not be structural because it is suspended and by the code... suspended ceilings are not structural.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Clearly this sparked a nerve. I'm guessing there is no clear definition? I would consider the grid type that infinity mentioned to not be structural because it is suspended and by the code... suspended ceilings are not structural.
It's a good question because there doesn't seem to be definitive answer. IMO the NEC could do a better job with the definition.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Why should the NEC define a building code item? The electrician should not be the one making these decisions as others trades are also impacted by the ceiling construction. Ask the architect or the AHJ.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Why should the NEC define a building code item? The electrician should not be the one making these decisions as others trades are also impacted by the ceiling construction. Ask the architect or the AHJ.
The question is related to dedicated equipment space in 110.26 which uses the term structural ceiling. How can one determine if the space above the ceiling is part of the dedicated space when there is no definition of structural ceiling?
 
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