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Insulation required by code at partly heated stair?

E

ETThompson

Registered User
Joined
May 19, 2017
Messages
186
Location
Columbus, Ohio
Hi

I have a small apartment project I'm working on. The units are served by an exterior breezeway, but we have enclosed stairs, disconnected from the main apartment block (originally they were open air, but because they are hard up against the property line we had to enclose).

MEP engineer plans to use baseboard heat but says cooling not required. 3 stories, VB Construction, new construction. About 10k sf for the project.

We are under the 2017 Ohio Building Code, which is based on the 2015 IBC. The Ohio Building Code adopts ASHRAE 90.1-2010 or IECC 2012.

Because of the enclosure chart in ASHRAE, which calls for R-7 or so for "semi-heated" spaces with mass walls, I'd always thought I had to insulate spaces like these. One of my colleagues tells me though she never has on her projects. I don't have a full copy of the ASHRAE standard.

Am I right in thinking that ASHRAE would require insulation for these spaces? Her argument is its not a "habitable space" and therefore does not require it.

Thanks
 
not from Ohio, so I'm not familiar with the climate, but most places in North America would not be considered a "habitable space" if it was only "semi heated", so her argument would not be logical to me (why is there a code for semi-heated if it is never habitable space?). I would guess that it is required, but a building official has simply never called her on it.
 
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You're right, the standard is applicable to spaces whether habitable or not. Her argument would have bathrooms, closets, halls, storage rooms, etc. at the exterior walls and inside the building envelope heated or cooled without insulation.
 
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ANSI/ASHRAE/IESNA Standard 90.1-2007
5.1.2.1(c)semi-heated space: “heated by a heating system whose output capacity is greater than or equal to 3.4 Btu/h·ft2of floor area but is not a conditioned space
5.1.2.2: Assumption of conditioned space:
“Spaces shall be assumed to be conditioned space and shall comply with the requirements for conditioned space at the time of construction, regardless of whether mechanical or electrical equipment is included in the building permit application or installed at that time.” except“…if approved by the building official”
ASHRAE 90.1 has tables that Require Prescriptive Insulation Minimums for “semi‐heated” spaces, including Mass Walls.

Contact your energy consultant or the Building Department
 
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I'm not a fan of the energy code, and so am far from an expert, but speaking as a building official - I think if you submitted your plan to me with this staircase outside of the building thermal envelope, and then you chose to provide a little bit of heat in it just because you wanted to, that I'd probably accept it. If it's within the thermal envelope though, I probably couldn't let that go.
 
Can the baseboard heaters the designer is wanting to use be cord-and-plug connected, instead of hard wired? Outside the envelope and plugged in instead of wired, the B.O. doesn't even need to know they're there.
 

CONDITIONED SPACE. An area, room or space that is enclosed within the building thermal envelope and that is directly or indirectly heated or cooled. Spaces are indirectly heated or cooled where they communicate through openings with conditioned spaces, where they are separated from conditioned spaces by uninsulated walls, floors or ceilings, or where they contain uninsulated ducts, piping or other sources of heating or cooling.

R402.1 General (Prescriptive). The building thermal envelope shall meet the requirements of Sections R402.1.1 through R402.1.5.

Exception: The following low-energy buildings, or portions thereof, separated from the remainder of the building by building thermal envelope assemblies complying with this section shall be exempt from the building thermal envelope provisions of Section R402.
1. Those with a peak design rate of energy usage less than 3.4 Btu/h · ft2 (10.7 W/m2) or 1.0 watt/ft2 of floor area for space-conditioning purposes.
2. Those that do not contain conditioned space.


Exempt. Plug in a heater and you're compliant.
 
Concur with Mark. As a reminder they enclosed the exit access stairway owing to the fire separation distance to the property boundary. Additionally nothing is permitted in the stair enclosure unless it serves the enclosure. If a receptacle is provided for a heater then it should comply with the applicable provisions of the code.
 
It's just a receptacle though, no? I don't know that it was installed for a heater - maybe there's a receptacle at every landing so the kids can plug in the phones they're staring at all the time..
 
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