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Townhome Units as separate buildings

S

Shams Gannon

GREENHORN
Joined
Sep 9, 2019
Messages
47
Location
Austin Texas
Hi, I'm trying to answer a question for my civil engineer regarding fire flow and he needs to know the area of the largest building on the site. We're doing a series of townhome units and a couple stacked duplexes. My understanding was that the IRC considered each Townhome unit as a separate building, however, the definition in Chapter 2 seems to counter that:

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Does the IRC consider each unit as a building, or are the units combined a building? If the code that references fire flow considers each townhome unit a separate building does that supersede?
 
Each dwelling unit in a townhouse building is a townhouse dwelling unit. The "building" is the overall structure enclosed by the exterior walls and roof.
 
I feel like this is a really simple question but it has me totally confused. Slightly different that the original question...

I can build a sfh on a zero-lot-line, with a 1-hr fire rated wall along the property line, and then come back and build a second sfh along that same property line, with another 1-hr rated wall, and then a third just the same, and these are each individual buildings, completely separate in the eyes of the code, right? However, if I was to build them all at once as townhomes, they're now considered one building?

In Texas we are not required to sprinkler one- and two-family dwellings, see below from state code:

1727209723286.png

However, since the reclassification of Townhome units, the city of Austin is asking three or more townhomes be sprinklered.

Even if we want to redefine the townhouse unit as a townhouse dwelling, it should still not be required to be sprinklered. We have three one family townhouse dwellings, right?
 
The answer to your question is yes, and no. Sometimes, and maybe. It depends on your perspective and what purpose your question serves.

They are considered "separate" if you're talking about private access (doors opening directly to outside, front and rear) and property lines. They're "separate" if you're talking about fire safety, one "building" should be able to burn to the ground without taking the other with it.

They are considered "one building" if you're building them. They are typically built as one project, with one foundation, and one roof. The weather protection (roof and siding) function as one building. There usually have to be HOA's, easements, and the like in place for maintenance, access, parking, utilities, mail, trash, etc...

You get the advantages of a multi-family building, primarily reduced construction costs. But you also get the advantages of a single-family house, primarily ownership.
 
Shams Gannon said:
I can build a sfh on a zero-lot-line, with a 1-hr fire rated wall along the property line, and then come back and build a second sfh along that same property line, with another 1-hr rated wall, and then a third just the same, and these are each individual buildings, completely separate in the eyes of the code, right?
Click to expand...
With a property line separating the dwellings they are single family dwellings. Without a property line two dwelling units are just that 2 dwelling units. Three or more dwelling units with or without property lines are town houses. A Townhouse has more fire restriction requirements such as parapets, or fire retardant sheathing on the roof and no roof penetrations within 4 ft

SFD no fire sprinklers zero setback
1 hour—tested in accordance with ASTM E119,
UL 263 or Section 703.3 of the International
Building Code with exposure from both sides

With Sprinklers
1 hour—tested in accordance with ASTM E119,
UL 263 or Section 703.3 of the International
Building Code with exposure from the outside

2018 IFC
FIRE-FLOW CALCULATION AREA. The floor area, in square feet (m2), used to determine the required fire flow.

SECTION B104
FIRE-FLOW CALCULATION AREA

B104.1 General.
The fire-flow calculation area shall be the total floor area of all floor levels within the exterior walls, and under the horizontal projections of the roof of a building, except as modified in Section B104.3.

B104.2 Area separation.
Portions of buildings that are separated by fire walls without openings, constructed in accordance with the International Building Code, are allowed to be considered as separate fire-flow calculation areas.

Don't assume your 2 hour fire barrier is equal to a 2 hour fire wall. construction requirements differ.
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How about the idea of meeting a minimum requirement instead of your current path. I've inspected in TX and never saw a decently constructed townhouse with understanding of fire separations of walls and roofs. I have 0 doubt that City of will squash your plans of trying to get around their requirements and you'll get permit issuance the 12th of never. Also structurally speaking I am wondering how you could stack those foundations next to each other with post tension and no separation or would you rebar the devil out of it
 
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