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An addition and substantial improvement

jar546

*****istrator
Joined
Oct 16, 2009
Messages
7,882
Location
Palm Beach County Florida
We all know that an addition to a home in the special flood hazard area must comply with the requirements under your floodplain ordinance.

At what point, however do you consider an addition as a trigger to upgrade the rest of the house if no other work is planned inside the house other than attaching the addition?
 

Robert

Registered User
Joined
Jan 29, 2016
Messages
225
Location
Pinole, CA
I don't know the answer but some jurisdictions will cite the 50% rule (ie: replace 50% of roof or siding and you need to replace all of it to conform to class A in the fire zones), or recently I hit their threshold of 1000 sq ft addition which triggered fire sprinklers throughout the whole house. We applied for an expensive AMMR which allowed fire sprinklers in only the addition (as opposed to the whole house). The most frustrating thing I learned is that everyone has their own definition of floor area.....the energy folks have their definition, the fire folks have theirs (called "fire area"), the building code floor area is based on height for habitable space, etc..... and none of them align.
 

ADAguy

Sawhorse
Joined
Sep 11, 2013
Messages
5,005
Location
California
If you add square footage, you expose yourself to more flood flow, thereby putting more stress on the existing construction.
 

Saugie53

Registered User
Joined
Jun 22, 2018
Messages
4
Location
Rhode Island
Jar, I know this question was asked a while ago but didn't see many replies so I figured I would throw my 2 cents in. The way its done in my jurisdiction is by a 50% rule which is considered substantial improvement...using your question as the example, if the total estimated cost of all work including painting, appliances, labor and materials for building the addition and all subs ect... equals or exceeds 50% of the value (appraised or assessed) of just the structure the addition is being attached to then the entire house must be raised to BFE plus 1 foot fretboard. It can be a real pain especially because alot of people dont do their research before planning the project, hiring everyone, getting the plans drawn up, and applying for permits
 

Paul Sweet

Sawhorse
Joined
Oct 17, 2009
Messages
1,332
Location
Richmond, Va
For purposes of the Natoinal Flood Insurance Program the FEMA Coastal Construction Manual says:
SUBSTANTIAL IMPROVEMENT: Improvement of a building (such as reconstruction, rehabilitation, or addition) is considered a substantial improvement if its cost equals or exceeds 50 percent of the market value of the building before the start of construction of the improvement.

 

Ty J.

Sawhorse
Joined
Aug 2, 2017
Messages
1,432
Location
Washington State
For purposes of the Natoinal Flood Insurance Program the FEMA Coastal Construction Manual says:
SUBSTANTIAL IMPROVEMENT: Improvement of a building (such as reconstruction, rehabilitation, or addition) is considered a substantial improvement if its cost equals or exceeds 50 percent of the market value of the building before the start of construction of the improvement.

I believe that this is the correct answer. Our municipal code, as I believe most jurisdictions will similarly do, is worded to match the FEMA language. Otherwise, your jurisdiction may find themselves crosswise with FEMA and end up on the naughty list that kicks you out of the FEMA insurance program.
 
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