Temperature Control in Buildings – What is the Minimum Heat Level Required in the Building Code?

Both the International Building Code and the International Residential Code have requirements for maintaining a minimum temperature in buildings. They do not have requirements for a maximum temperature in buildings though there are ventilation system requirements and there are reasonable standards for comfort.

The IBC requires that interior spaces that are intended for human occupancy need to be able to maintain a minimum interior temperature of 68 degrees at a point 3 feet above the floor. This can be done actively, passively or with a combination of the two methods. The system design is based on the design heating day for the location.

The IRC is slightly more forgiving, it says that the 68 degrees must be maintained at a point 3 feet above the floor and 2 feet from the exterior wall. You only have to provide the system where winter design temperatures are below 60 degrees. Portable space heaters can’t be used to meet the requirement.


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2 thoughts on “Temperature Control in Buildings – What is the Minimum Heat Level Required in the Building Code?”

  1. Jim, my reading of the code states that it has to be capable but it doesn’t say unattended. Ultimately the inspector will have the final say of course.

  2. Hi, per the IRC (I’m in Michigan) does the heating system to maintain minimum have to be an unattended system? If so, for how long can it be unattended?

    I have a small propane heater (wall mount, direct vent, thermostaticly controlled) intended to keep the house above freezing when unoccupied. I use wood when I’m there. The wood system is more than up to the job, but of course it requires manual intervention to keep it going.

    The mechanical inspector claims I have to have an automatic heating system capable of meeting the 68 degree 3′ off the floor requirement.

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