# 2 Buildings 1 Lot



## jar546

Here is a scenario to think about.

1 Lot with two-3 story dwelling units proposed to be constructed.  The two dwelling units share a below grade wall but are otherwise separated with walking space in between ranging from 10' to 4' where there is an offset.  The buildings are sprinklered.  Since there is only 1 lot, they don't meet the definition of a Townhouse. They don't share any interior or exterior space. Therefore:

The IBC applies
This is now considered 2 condominiums and R2.
They are individual dwelling units but can't be considered Single Family Residences.

What is your take?
What if they want to subdivide in the future?


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## steveray

Not sure where you are getting the "one lot/ not a TH" thing?


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## jar546

steveray said:


> Not sure where you are getting the "one lot/ not a TH" thing?


Does not meet the definition of a townhouse in the FBC.

[RB]TOWNHOUSE. A single-family dwelling unit not exceeding three stories in height constructed in a group of two or more attached units with property lines separating such units in which each unit extends from foundation to roof and with a yard or public way on not less than two sides.


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## steveray

[RB] TOWNHOUSE. A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from foundation to roof and with a yard or
public way on not less than two sides.

I get 3 or more units, but nothing about a lot....Can't do it as a 2 family?


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## jar546

This is how one of our neighboring cities defines Duplex/Two-Family Dwelling

_Duplex/Two Family Dwelling
A. Definition. For the purposes of this section, a duplex is defined as a building designed for and containing two (2) single family dwelling units entirely under one (1) roof that are completely separated from each other by one (1) dividing partition common to each unit and with each dwelling unit constructed on a separate lot. A two (2) family dwelling is defined as a building constructed on a single lot that is designed for and contains two (2) single family dwelling units entirely under one (1) roof that are completely separated from each other by one (1) dividing partition common to each unit_


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## jar546

Here is what my Town says in the ordinance under definitions:
_Dwelling, two-family (duplex) means a residential building containing two (2) dwelling units which share a common interior wall or walls._


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## steveray

Two family based on the shared below grade wall?


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## jar546

steveray said:


> Two family based on the shared below grade wall?


ehhh


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## Pcinspector1

jar546 said:


> Here is what my Town says in the ordinance under definitions:
> _Dwelling, two-family (duplex) means a residential building containing two (2) dwelling units which *share a common interior wall or walls.*_



Doesn't mention floors.. humm

how do they handle a tri-plex?


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## classicT

Why not just call it two SFD on one lot? The IRC does not prohibit this (although zoning codes typically do), but specifies the minimum fire separation distance per _IRC Section 302.1.
_
*FL IRC - R302.1 Exterior Walls*
Construction, projections, openings and penetrations of exterior walls of dwellings and accessory buildings shall comply with Table R302.1.
*Exceptions:*

Walls, projections, openings or penetrations in walls perpendicular to the line used to determine the fire separation distance.
Walls of dwellings and accessory structures located on the same lot.
Detached tool sheds and storage sheds, playhouses and similar structures exempted from permits are not required to provide wall protection based on location on the lot. Projections beyond the exterior wall shall not extend over the lot line.
Detached garages accessory to a dwelling located within 2 feet (610 mm) of a lot line are permitted to have roof eave projections not exceeding 4 inches (102 mm).
Foundation vents installed in compliance with this code are permitted.
Screen enclosure walls of insect screening with a maximum of 25-percent solid flexible finishes.
For zero lot line developments where permitted by local regulations, openings and roof overhang projections shall be permitted on the exterior wall of a building located on a zero lot line when the building exterior wall is separated from an adjacent building exterior wall by a distance of 6 feet or more, and the roof overhang projection is separated from an adjacent building projection by a distance of 4 feet or more, with 1-hour fire-resistive construction on the underside of the overhang required, unless the separation between projections is 6 feet or more.
Take note that dwellings (red) is plural. Therefore, treat it similar to the IBC, run an imaginary lot line down the middle (or to one side), and meet the fire-resistance construction requirements of Table R302.1.


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## Glenn

Ty J. said:


> Why not just call it two SFD on one lot? The IRC does not prohibit this (although zoning codes typically do), but specifies the minimum fire separation distance per _IRC Section 302.1.
> _
> treat it similar to the IBC, run an imaginary lot line down the middle (or to one side), and meet the fire-resistance construction requirements of Table R302.1.



No need to bring up IBC.  The IRC definition for FSD includes measurement to an imaginary line.  That's why it's there.  I recently edited down this very subject from a webinar I presented to make a short video.


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## Glenn

jar546 said:


> Does not meet the definition of a townhouse in the FBC.
> 
> [RB]TOWNHOUSE. A single-family dwelling unit not exceeding three stories in height constructed in a group of two or more attached units with property lines separating such units in which each unit extends from foundation to roof and with a yard or public way on not less than two sides.



Ha, ha!  This is why politicians should not amend the I-Codes!  Sorry, Jar, but that was a stupid amendment from folks that don't seem to understand the line between building codes and zoning ordinances.  I know that sounds rude, but I'm just being a straight-talking smart ass.  I am growing very exhausted of state and local code amendments.


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## Glenn

Pcinspector1 said:


> Doesn't mention floors.. humm
> 
> how do they handle a tri-plex?


Or simply a two-family dwelling with one above the other and an exterior stairway for grade access.  This is why states shouldn't amend I-codes.


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## ADAguy

Oh the web we weave?!


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## jar546

Here we go:


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## jar546

For us this is a condo


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## steveray

We do not have condos in our code....I would (be willing to) call that a 2 family....depending on the rest of the details...


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## classicT

I am with Steveray... In WA we would call that a 2-family dwelling, which may be constructed per the IRC.

The walls 4-ft from the property line, where the compressor units are, would need to be 1-hr.


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## TheCommish

seem to me there are a lot of ACCU for  2  dwelling units. Discounting that issue if each  dwelling unit has 2 independent means of egresses it is a duplex


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