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Change of plan - openings between townhouses

R302.1 Exterior walls.

Construction, projections, openings and penetrations of exterior walls of dwellings and accessory buildings shall comply with Table R302.1.

Exceptions:

1. Walls, projections, openings or penetrations in walls perpendicular to the line used to determine the fire separation distance .

2. Walls of dwellings and accessory structures located on the same lot .

They are not on the same lot therefore according to Table 301 openings are not permmitted within 3 ft of a lot line. Yankee is correct in that ownership is not talked about in the code but lot lines are

FIRE SEPARATION DISTANCE. The distance measured from the building face to one of the following:

1. To the closest interior lot line ; or

2. To the centerline of a street, an alley or public way; or

3. To an imaginary line between two buildings on the lot .
 
If the zoning would allow for a duplex, replat into a single lot, and add a rated door with automatic closer. If the zoning would only allow only for single family, replat into a single lot, add a door or cased opening of your choosing, and interconnect all smokes.
 
Jobsaver said:
If the zoning would allow for a duplex, replat into a single lot, and add a rated door with automatic closer. If the zoning would only allow only for single family, replat into a single lot, add a door or cased opening of your choosing, and interconnect all smokes.
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Agree you have to do something with the existing lot line in order to allow the opening.
 
I believe section R302.1 Exterior Walls discusses muliple individual structures on a lot or near each other across a lot line, hence exterior walls. The term "interior lot line" does not mean a lot line interior of a building, but instead, interior to a lot.
 
LOT. A portion or parcel of land considered as a unit.

LOT LINE. A line dividing one lot from another, or from a street or any public place.

R106.2 Site plan.

The construction documents submitted with the application for permit shall be accompanied by a site plan showing the size and location of new construction and existing structures on the site and distances from lot lines

We have parent lots with interior lot lines creating sub-lots Example the parent lot would be #123 the sub lots would be #123A and #123B. But they are still individuall lots.
 
Require a 45 minute rated door for the required 1 hour separation in the two family dwelling and issue the permit.

That's far and away better than the unrated door which will go in if you deny the permit.
 
brudgers said:
Require a 45 minute rated door for the required 1 hour separation in the two family dwelling and issue the permit.That's far and away better than the unrated door which will go in if you deny the permit.
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This was similar to my first thought, but......(I'm braced for a barrage of admonishments for "what-ifing"), it appears that their idea is to have a cased opening, leaving the units completely open to one another. I would fully expect them to remove the rated door after C of O, and thereby defeat the purpose thereof. The structure more closely resembles a two-winged SFD, so I think treating it as such (single electrical service, interconnected smokes) is the more appropriate way to proceed, given the knowledge we currently have.

Disagree?
 
Do both.

Rated door and interconnected. If they complian about the interconnected then you can go down that road but chances are they won't. If they remove the door, you're covered.

The code does not care if there is a single electrical service for two units as long as both can get to the overcurrant devices.
 
Code Neophyte said:
The structure more closely resembles a two-winged SFD, so I think treating it as such (single electrical service, interconnected smokes) is the more appropriate way to proceed, given the knowledge we currently have.Disagree?
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As I said above: the halves are owned by different parties. Therefore you should not do what you intend.

To do what you want would require that the same party own both halves.
 
GHRoberts said:
As I said above: the halves are owned by different parties. Therefore you should not do what you intend.To do what you want would require that the same party own both halves.
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Where in the code is that written?

It is a duplex dwelling unit that has been "condo-ized". The building code does not care if it is a duplex structure or a duplex condo structure.

A rated door between the units consistent with the wall rating. Done.
 
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Do these places have separate electrical meters? I would imagine they do.

I'm not an electrician, but I think that interconnecting the smokes would open a huge can of worms with regard to the entire electrical system(s).

Also, connecting them as one dwelling would be problematic with regards to the electrical system in general.
 
Conversion would be easy. One would just have to link the last interconnected smoke in unit A to the first interconnected smoke in unit B. To identify, the last smoke in A will have only one romex cable feeding the smoke. The first smoke in B will have direct supply from outside the smoke alarm system (usually 14/2 or 12/2 WG). Isolate the supply wire feeding B and remove from smoke alarm system. Then, run 3-wire link from unit A to unit B and interconnect.

All this assuming a typical installation that can be verified with some basic testing.
 
Code Neophyte said:
This was similar to my first thought, but......(I'm braced for a barrage of admonishments for "what-ifing"), it appears that their idea is to have a cased opening, leaving the units completely open to one another. I would fully expect them to remove the rated door after C of O, and thereby defeat the purpose thereof. The structure more closely resembles a two-winged SFD, so I think treating it as such (single electrical service, interconnected smokes) is the more appropriate way to proceed, given the knowledge we currently have.Disagree?
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Yep. I would treat it as two family since in the long run someone will try to use it that way.
 
I've seen (several times) a stipulation put (by the building department) in the public record that when ownership changes, the 1 hour wall is to be restored. $19 filing fee.
 
Thanks, Peach. I was thinking in the back of my mind that it really could be as simple as that. I'm having a meeting this morning to discuss the situation; may have more information later in the day.

thanks again..
 
Guys, help me out here. For those of you who say the code allows openings in dwelling unit separation, where are you getting that? 317.1 ( 302.3 in '09) requires 1 hr wall assembly. It goes on to talk about through penetrations and membrane penetrations, but nowhere does it allow openings, rated or not.

As many of you have said, I'm sure I could and would make it work through deed attachments and/or zoning, but in the code as written, I do not think openings would be permitted.
 
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I think texasbo is correct. Under the IRC, there appears to be no exception for adding a door assembly, rated or not.

I change my solution to the OP to be: Replat into one lot, interconnect all smokes, and add a door or cased opening of your choosing.
 
Jobsaver,

I can see why it would be relatively easy to interconect the smokes and eliminate one end from the 2nd meter. But, what about the rest of the wiring. If the units are combined into one, can it still have 2 meters? I think not. I suppose they would need to install a sub panel from the one power source, disconnet the meter from "unit 2" and get power to the 2nd unit from the 1st unit(??)

Maybe I'm over thinking this, but I believe it would be a potentially hazardous condition to have 2 power sources to the same building (if they were combined).
 
@ @ @ @

Glennman,

If the services and all associated circuitry are already separated, where's

the hazard [ no backfeeds that I can determine ]?.......All that is being

combined [ essentially ] is a piece of paper combining the two separate

parcels/structures in to one parcel/structure..........All existing systems

would remain as is.



@ @ @ @
 
Think about other rated partition walls though. In other scenarios there will be a rated exit hallway with (rated) doors from adjacent units opening into the hallway. So although the residential code doesn't expressly prohibit or allow a doorway, this concept as a means of compliance with the intent of the code in this unusual situation is permitted by the building code with other residential uses.
 
Glennman CBO said:
If the units are combined into one, can it still have 2 meters?
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Yes. There is no reason a single family home could not have multiple meters. I do recommend isolating the power that feeds one of the smoke alarm systems, by isolating the feed into its own jbox. Then, as previously posted, proceed to interconnect all smoke alarms on the smoke alarm circuit remaining.

Each hemisphere of the "new" single-family home would be individually metered, except for the smoke-alarm circuit which will pull from one side or the other.
 
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