Do closets, bathrooms, and attics need sprinklers? Where a 13D system can skip heads in a DC rowhouse

The first question on almost every rowhouse design call is some version of “do I really need a head in the coat closet.” The honest answer is that NFPA 13D, the standard the District uses for one and two family houses, lets a designer leave heads out of a specific short list of spaces, and everywhere else gets one. This article walks the list, explains the conditions attached to each item, and points out the DC rowhouse features that trip people up: the cellar, the rear addition, the roof deck stair, and the party wall closet.

Why 13D skips anything at all

13D is a life safety standard, not a property protection one. Its job is to control a fire in the room where it starts long enough for the people inside to get out. That framing is why it tolerates leaving heads out of small spaces where a fire is unlikely to trap anyone, and why the list is short. The 13D versus 13R article explains where 13D stops applying. A three unit conversion or a small condo building is on 13R, and 13R’s omission list is different and shorter. Everything below is about the single family rowhouse and the two family house with an English basement.

The spaces 13D lets you leave out

The standard lists these in one section, and every item carries a condition. Meeting the size limit is not enough if the other condition fails.

• Bathrooms up to 55 square feet. A typical rowhouse hall bath at 5 by 8 is 40 square feet and qualifies. A primary bath with a separate shower and a water closet room often does not, and once it crosses the line the whole room gets covered, not just the extra.
• Clothes closets, linen closets, and pantries up to 24 square feet with a least dimension of 3 feet or less, and with walls and ceilings of noncombustible or limited combustible material. Plaster and drywall pass. A cedar lined closet does not. A walk in closet at 5 by 6 is 30 square feet and gets a head.
• Garages, carports, open attached porches, and exterior balconies. The rear parking pad with a roof over it counts as a carport. An enclosed rear addition that used to be a porch does not, and this is the item that catches the most DC houses.
• Attics, crawl spaces, and concealed spaces that are not used or intended for living and that contain no fuel fired equipment. Put a furnace or a gas water heater in the attic and the exemption goes away for that space.
• Entrance foyers that are not the only way out of the house.

The DC rowhouse cases

Four features show up in District houses often enough that we check them on every survey.

The front cellar. A dirt or brick floor space under the front porch with the water meter in it is a crawl space if it is under 5 or 6 feet and nobody lives in it, and it can be left out. Frame the ceiling, run a floor, and put a washer in it, and it becomes a room. The moment it becomes a room it gets heads, and if it has the furnace it was never exempt in the first place.

The rear addition. Most rowhouses have gained a rear kitchen or sunroom since they were built. If it is heated and enclosed, it is living space and gets covered. If it is an unheated sunroom, it still gets covered, and then the pipe in the ceiling becomes a freeze problem. The pipe materials article covers the usual answer, which is a dry sidewall head fed from the heated side of the wall.

The roof deck stair and bulkhead. A stair to a roof deck is part of the house and the enclosed stair gets a head at the top. The deck itself is an exterior balcony and does not. People sometimes expect the reverse.

Closets against the party wall. Rowhouse closets are often deep and narrow because they fill the space between a chimney breast and the party wall. A closet at 2 by 10 is 20 square feet but its least dimension is 2 feet, so it qualifies. A closet at 4 by 6 is 24 square feet but its least dimension is 4 feet, so it does not. Both dimensions have to pass.

What exemptions do to the cost

Less than you would hope. A rowhouse sprinkler system is priced on the cost page per sprinklered square foot, and the exempt spaces are small. Leaving heads out of two hall baths and four closets removes a handful of heads from a system of thirty or forty. Where the exemptions do save real money is in the retrofit, because every head that is not required is a ceiling that does not have to be opened, and in an occupied house with plaster ceilings that can be the difference between the low and high end of the $2 to $7 per square foot retrofit band. On new construction at $1.35 to $1.60 per square foot the exemptions barely move the line item.

What the plan reviewer looks for

DOB plan review reads the sprinkler sheets against the architectural floor plan, and every room without a head needs to be a room on the exempt list with its area shown. A closet drawn without dimensions gets a comment. A bathroom labeled “bath” with no square footage gets a comment. The permit steps article covers the rest of the review, but on the coverage question the fix is simple: dimension every exempt space on the sprinkler sheet so the reviewer can check the math without asking.

The final inspection checks the same thing in the field. An inspector who finds a closet that grew during framing, or an attic that got a furnace during the mechanical rough in, will ask for a head there before signing. Those are the two changes that most often happen between the drawings and the inspection, and both are cheap to catch early and expensive to catch at the end.

Omitting a head that could have been skipped

There is one more question that comes up: can the owner ask for more heads than required. Yes, and it is sometimes worth it. A head in a walk in closet full of clothes, or in a rear addition used as a home office, costs little at the design stage and protects the space where a fire in that house is most likely to start. 13D sets a floor. The drawings can go above it.

Quick checklist

1. Measure every bathroom and closet. Write the area and the shortest wall on the floor plan.
2. Note which closets have anything other than plaster or drywall on the walls.
3. List every space with a furnace, boiler, or gas water heater. None of those are exempt.
4. Decide now whether the rear addition and the cellar are living space, because that decision is what the reviewer will read.
5. Dimension every exempt space on the sprinkler sheets before they go to DOB.