Code Check: Residential Renovation + Sprinklers in Montgomery County

9/16/2021

The International Residential Code requires an automatic sprinkler system in all single-family and two-family dwellings (par R313.2 in IRC 2018). The IRC has an exception: sprinklers are NOT required for additions or alterations to existing buildings that are not already sprinklered. But...

Montgomery County added their own provision (in Regulation 4-15AMII daed 8/3/2015) adding paragraph R313.4 requiring that sprinklers be installed in existing houses when either:

50% or more of the gross floor area of the existing building is demolished. This excludes basements. The gross floor area in this one and only case is measured to the inside of exterior walls; it includes stairs, interior walls, and everything else inside.
50% or more of the exterior walls are demolished (not including foundation). Oddly unlike the floor area provision, this is measured from corner to corner on the exterior, and includes any part of the wall such as top plate or sheathing.

However, Montgomery County does NOT require sprinklers for additions if the house is not sprinklered - regardless of size (unless, of course, in building that addition you are also doing 50% demolition of either floor area or exterior wall).

For new houses, the county has required sprinklers since 1/14/2004. If by some fluke your house was built after that without sprinklers, you will have to add them when you renovate or expand. Residential sprinklers are designed based on NFPA 13D, which is significantly simpler than NFPA 13R (multifamily) and NFPA 13 (taller multifamily and commercial).

2 Comments

Deborah Buelow link

2/1/2022 05:53:33 am

Hey Scott, thanks for your thoughts on this! I was just setting down to research sprinkler requirements in MontCo and found this. Thanks for making it easy :)

Grand Rapids Contracting link

12/16/2024 04:38:40 am

Great insights on residential renovations and sprinkler requirements in Montgomery County! It’s essential for homeowners to stay informed about local regulations when planning any type of home project. Similarly, when considering a home addition, it's important to follow all safety codes, which can vary depending on the location and scope of the work.

If you're looking to expand your home with professional Home Addition Services in Grand Rapids, MI, Grand Rapids Contracting is here to help. Our team is well-versed in local building codes and ensures that your home addition is not only beautiful but also up to code. Whether you’re adding a new room, expanding your living space, or enhancing your home’s functionality, we provide high-quality solutions that meet your needs.

Feel free to reach out to us for expert advice and reliable home addition services near you!

Code Check: Residential Renovation + Sprinklers in Montgomery County

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