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Where is 'missing middle' allowed to be built under IRC?

Is another way to look at this to take the IBC and determine which are the most difficult (and least useful/important) things for very small projects to comply with and then make adjustments to the IBC just for those small projects? it seems like the IBC is really intended for very large projects, and the smaller you get the worse it is. Is there some sort of happy medium?
 
Curious Coder said:
Is another way to look at this to take the IBC and determine which are the most difficult (and least useful/important) things for very small projects to comply with and then make adjustments to the IBC just for those small projects? it seems like the IBC is really intended for very large projects, and the smaller you get the worse it is. Is there some sort of happy medium?
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This is the route Nashville is taking with their NEST resolution. Check out the language here: https://nashville.legistar.com/Legi...49E5-8884-B8F8E60D4C01&ID=6500905&FullText=1v

I think bringing these units into the IRC, a la Shelby County (Memphis), would be more impactful. The ‘Large Home’ definition used in Shelby County has fireproofing and egress well defined and allows for local GCs to use their subs more comfortable with the IRC.
 
I think it's paradoxical that the IRC regulates "detached one- and two-family dwellings and townhouses" but doesn't define what a two-family dwelling is. My state added a definition:

TWO-FAMILY DWELLING. A building containing two
dwelling units with not more than six lodgers or boarders per
dwelling unit.
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It doesn't say the two dwelling units have to be side-by-side, nor does it say one can't be above the other.

The ICC IRC scoping goes on to say "with a separate means of egress." My state didn't change that, but there are plenty of ways to design a duplex with a separate means of egress for the upstairs unit.
 
[RB] DWELLING. Any building that contains one or two dwelling units used, intended, or designed to be built, used, rented, leased, let or hired out to be occupied, or that are occupied for living purposes.

[RB] DWELLING UNIT. A single unit providing complete independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation. For the definition applicable in Chapter 11, see Section N1101.6.

R302.3 Two-family dwellings.
Dwelling units in two-family dwellings shall be separated from each other by wall and floor assemblies having not less than a 1-hour fire-resistance rating where tested in accordance with ASTM E119, UL 263 or Section 703.3 of the International Building Code. Fire-resistance-rated floor/ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend from the foundation to the underside of the roof sheathing.
 
TWO-FAMILY DWELLING. A building containing two
dwelling units with not more than six lodgers or boarders per
dwelling unit.

That would be hard to enforce. My daughter has 7 children. Looks like this would apply regardless of the size of the units, 800 sq ft or 2,800 sq ft per unit.
 
Ye
mtlogcabin said:
TWO-FAMILY DWELLING. A building containing two
dwelling units with not more than six lodgers or boarders per
dwelling unit.

That would be hard to enforce. My daughter has 7 children. Looks like this would apply regardless of the size of the units, 800 sq ft or 2,800 sq ft per unit.
Click to expand...
Yeah. Building code does family planning. Leave it to the politicians.
 
I don't see a limit on family members, just lodgers or borders who would be renters.

If I remember correctly there used to be similar limits in building or zoning codes, but the Feds said they were illegal. I think it was when they required group homes to be allowed in single family areas.
 
Are lodgers and/or boarders defined in the code? If one of the family members pays rent, are they now a lodger? If none of them pay rent but they're all unrelated, are more allowed?

Bad code.
 
I am trying to find the IRC requirement that two units (one on top of the other) have to be built under the IBC, though that is what I expect. Can one of you point me to that code section or definition?
 

R302.3 Two-family dwellings.
​

Dwelling units in two-family dwellings shall be separated from each other by wall and floor assemblies having not less than a 1-hour fire-resistance rating where tested in accordance with ASTM E119, UL 263 or Section 703.2.2 of the International Building Code. Such separation shall be provided regardless of whether a lot line exists between the two dwelling units or not. Fire-resistance-rated floor/ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend from the foundation to the underside of the roof sheathing.
Exceptions:
  1. 1.A fire-resistance rating of 1/2 hour shall be permitted in buildings equipped throughout with an automatic sprinkler system installed in accordance with Section P2904.
  2. 2.Wall assemblies need not extend through attic spaces where the ceiling is protected by not less than 5/8-inch (15.9 mm) Type X gypsum board, an attic draft stop constructed as specified in Section R302.12.1 is provided above and along the wall assembly separating the dwellings and the structural framing supporting the ceiling is protected by not less than 1/2-inch (12.7 mm) gypsum board or equivalent.
 
I think it's legal to go with the IRC for that kind of thing, unless I am misunderstanding the question?
 
mtlogcabin said:
TWO-FAMILY DWELLING. A building containing two
dwelling units with not more than six lodgers or boarders per
dwelling unit.

That would be hard to enforce. My daughter has 7 children. Looks like this would apply regardless of the size of the units, 800 sq ft or 2,800 sq ft per unit.
Click to expand...

The building code does not put a limit on the size of a family that can occupy a unit.
It does put a limit on the number of unrelated people who are paying to live in a single dwelling unit (“lodgers” who pay to sleep and “boarders” who pay to sleep and be given food). Above that amount, it reclassifies the building under a different type of occupancy.
 
Beniah Naylor said:

R302.3 Two-family dwellings.​

​

Dwelling units in two-family dwellings shall be separated from each other by wall and floor assemblies having not less than a 1-hour fire-resistance rating where tested in accordance with ASTM E119, UL 263 or Section 703.2.2 of the International Building Code. Such separation shall be provided regardless of whether a lot line exists between the two dwelling units or not. Fire-resistance-rated floor/ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend from the foundation to the underside of the roof sheathing.
Exceptions:
  1. 1.A fire-resistance rating of 1/2 hour shall be permitted in buildings equipped throughout with an automatic sprinkler system installed in accordance with Section P2904.
  2. 2.Wall assemblies need not extend through attic spaces where the ceiling is protected by not less than 5/8-inch (15.9 mm) Type X gypsum board, an attic draft stop constructed as specified in Section R302.12.1 is provided above and along the wall assembly separating the dwellings and the structural framing supporting the ceiling is protected by not less than 1/2-inch (12.7 mm) gypsum board or equivalent.
Click to expand...
Thank you!
 
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