Expert: Roger Zona - 1/12/2012

Question
I've got a building built in the 1930s. I believe a class "b" construction definition. It has an area under the subfloor plenty enough to stand up in. The subfloor above is a combination wood/slab. There is no ventilation, (grade deviated above windows/vents. There is also no sump area or insulation or vapor retarder.
My questions are:
1: What qualifies as a basement or subterranean crawlspace? What qualifications set them apart? I'm confused how a basement definition specifically is interpreted. Code or IBC references would be great.
2: If I were to remodel or add on, what would I have to do in order to bring it up to code?

Thanks very much in advance....

Answer
Hey Danny,

Codes vary from place to place, state to state, etc. and therefore I can't reference a specific code.  However, a "crawl space" is defined as the open space under a structure that allows the installation of required pipes, ducts, wires and structural devices.  The space can vary from 24" to several feet.  Generally there is no floor in the crawl space other than soil.  Frequently I have installed 2" thick unfinished concrete slurry to seal the space.  Generally again, there are means of access and ventilation to the space.  The ventilation means usually are screened grills similar to eave venting and the access door must be of a suitable size to allow a person to crawl into the open space.  

A basement is defined as a finished space below a structure with access from within the structure.  An additional exterior access is also allowed.  Basement space has a finished floor - usually 4" of concrete and, depending on the surrounding soil conditions, a sump to pump out excess water.  Also, windows can be provided.  These can be of various sizes depending on he use of a window well on the exterior.  A typical basement window is 32" wide by 16" high and is of a module size to fit within concrete blocks.

A building as old as yours may be confronted with major modification to meet current building codes.  For example, here in Florida, if remodeling a building exceeds a pre-determined value, the entire structure must be modified or remodeled to meet current codes.  That's a brief explanation and it varies depending on location, method of construction, and local code amendments to the Florida Building Code.  

I suggest you meet with your local building official.  He can give you specifics about the existing structure and what you must do to modify the structure to meet codes.  As a caution; if the building is considered "commercial" and you increase the usable area of the building, you may be required to provide additional parking for the general public.  

I hope this has been helpful.

Roger
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