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Buildings Across Lot Lines
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Buildings Across Lot Lines By  Robert Risk

Posts: 1

10/3/2012 4:48:05 PM

We have a situation where many of the homes and commercial buildings in town are built on multiple lots. Literally, some of the larger buildings might have 4 or 5 property lines running through them.


I'm looking for specific language in the IBC and IRC that would prohibit construction across lot lines. There's not much we can do about the existing building, but when there is a major renovation or an addition on one of these structures, we'd like to start asking that they consolidate the multiple lots into a single compliant lot with the proper code approved setbacks to the property lines.


The IBC and IRC clearly address buildings on a lot and have requirements for various distances to a property line but with the exception of requirements for town homes, they do not (that I can find) specifically address construction across that line.


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Buildings Across Lot Lines By  Gary Brackins

Posts: 66

10/3/2012 5:43:04 PM

Welcome to the Forum Robert!

does your zoning state one structure per lot?

does your zoning provide setbacks from front, rear and side lot lines?

the simplest means of accomplishing this is through your existing zoning setbacks. hold the setbacks from the interior lot lines, unless they have their deed rewritten to remove the interior lot lines. Now they will combine the two, three or four lots they have into one larger lot.

this is how we do it ....... don't know if this helps or not



"If you don't have time to do it right the first time, when will you find the time to fix it?"

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Buildings Across Lot Lines By  Dennis Keierleber

Posts: 366

10/4/2012 11:05:35 AM

To begin with the building codes aren't really concerned with ownership. If the condition doesn't present a safety hazard, it may not be of any concern to code enforcement. Generally, the planning and administrative types find this messy and would want the lot line abandoned if the building straddles the line.

As far as examples, where the building is divided into separate structures, even with a common wall, this is a pretty normal condition. In the opposite condition, multiple buildings on a single lot, the code specifies an imaginary lot line. When there are multiple buildings on a lot, they may be treated as a single building for area, thereby eliminating the need for fire-resistant rated construction, or they may be treated as individual buildings with fire separation distances to the immaginary lot line.

One interesting example I ran accross is where there were two older buildings with a common wall and a lot line centered on the common wall. The same tenant wanted to lease both buildings and create an opening between the two. The owner did not want to abandon the lot line because of future sales or uses. Is this really a matter of concern for building code enforcement? The building either works for area as all one building or it gets a rated closure to maintain the fire wall and the separated buildings. The existence of the horizontal exit would make the buildings more safe, not less. 

DK Engineering PLLC

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Buildings Across Lot Lines By  Mac

Posts: 91

10/4/2012 3:01:35 PM

The IBC regulates new construction fire resistance factors based on the proximity to lot lines. The closer a building is to a lot line, the more fire resistance should increase, primarily to prevent the spread of fire from one building to an adjacent one.

Strictly speaking, it would likley be easier for an owner to combine two lots into one, than design a new building with a lot line throught the middle. Ownership of the lots is not mentioned in Ch.7 IBC.

How old are the existing buildings? Does these lot lines go way back in local history?  

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Buildings Across Lot Lines By  Art Balourdas

Posts: 1

11/13/2012 3:32:55 PM

There is nothing in the building code that explicitly prohibits building over lot lines. The rationale jurisdictions use is that since the building code regulates protection of walls depending on their distance from property lines then if you build over one you would have to comply with those requirements at the property line you build over and this would result in a builidng with a fire wall going thru it at the property line. They want you to remove the property line so the protection issue goes away. How this contributes to making the building safer is beyond me. This is bizarre logic and even more bizarre when it's an existing building and they want the lot line removed as a condition of a permit for the addition. They just want it done to remove the "ambiguity." As usual this make them happy but cost the owner money and accomplishes nothing.

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