Pop up and third story additions in DC: when the whole rowhouse has to be sprinklered

Walk any block in Shaw, Bloomingdale, or Petworth and you will see them: a two story rowhouse with a third floor stacked on top, sometimes matching the brick, often not. The pop up is how DC adds bedrooms without adding lots. The question we get from owners and their architects is simple. Does putting a floor on top mean the whole house needs fire sprinklers? The honest answer is sometimes, and the difference between yes and no is decided by how the permit set describes the work, not by the size of the addition.

What DC’s residential code says about new houses

The District adopted the residential code with the fire sprinkler requirement for new one and two family dwellings intact, which is why every new rowhouse and every new build on an infill lot in the city carries an NFPA 13D system. Our new construction page covers that side. That part is settled. The gray area is everything that happens to a house that already exists.

How the model code treats additions

The model residential code exempts additions and alterations to an existing house that was not already sprinklered. The reasoning is that requiring a full system every time someone adds a bedroom would stop people from pulling permits at all.Under that reading, a straightforward third floor on a house that stays a single household does not by itself pull the house into the sprinkler rule. Three things change that.

• A change in unit count. If the pop up creates a second dwelling, or the basement becomes an apartment as part of the same permit, the house is now a two family dwelling and the change of occupancy carries the sprinkler requirement with it. The ADU article covers that path.
• A substantial alteration. When the addition comes with a gut of the existing floors, new floor framing, a new roof structure, and reconfigured stairs, plan review can treat the result as substantially new construction and apply new construction rules.
• A new dwelling classification. Some pop ups leave so little of the original house standing that the reviewer classifies the project as a new building on an existing foundation. That is a new dwelling and it gets a 13D system, full stop.

How plan review actually classifies it

The Department of Buildings reads the scope of work on the application and the demolition plan in the set. If the architect writes “third floor addition and interior renovation” and the demolition sheet shows every partition coming out, the reviewer is going to ask whether this is an alteration or a reconstruction. If the answer is reconstruction, the fire reviewer will comment that a sprinkler system is required and the set goes back. We have seen that comment arrive on projects in Capitol Hill and Brookland where nobody had budgeted for it, at the point where the framing was already priced.

The way to avoid the surprise is to ask the question before submission. Most architects who work in the District know where the line is and will tell you which side of it your project sits on. If the project is close to the line, decide on purpose. Some owners choose to sprinkler anyway because they are opening every ceiling already, and the marginal cost is as low as it will ever be.

Zoning height limits shape the decision too

The pop up boom produced a zoning response. In the residential rowhouse zones the by right height was lowered and a third story on a two story house now often needs to fit inside a tighter envelope, with a special exception for anything above it.The same amendments also limited the conversion of rowhouses into three or more units in those zones. That matters here because the projects most likely to be classified as new dwellings, the full gut with added units, are also the ones most likely to need zoning relief. If your project needs a hearing, the sprinkler question should be answered before the hearing date, not after.

The water service question

A third story raises the highest sprinkler head in the house by about ten feet, and every foot of elevation costs pressure. A three quarter inch service that would have squeaked through the calculation on a two story house usually does not on a three story one. Before the drawings are far along, find the service size where it enters the basement and have the static pressure read. Our water service sizing article explains the calculation and the DC Water and DDOT steps involved in an upgrade. Owners adding a full bath on the new floor tend to benefit from the bigger pipe regardless.

What it costs when the answer is yes

Those are the only numbers we publish, and the cost page explains the spread. A pop up is a hybrid job by nature: the new floor prices like new construction and the floors below price like a retrofit, with the split depending on how much ceiling is open when we arrive.

What we tell owners at the first call

Three questions settle most of it. Is the unit count changing? How much of the existing interior is coming out? What size is the water service? With those answers we can say whether the project is likely to be classified as an addition or as a new dwelling, and what the system would cost either way. The decision to sprinkler a house that is not strictly required to be sprinklered is the owner’s. Our job is to make sure it is a decision and not a review comment.

Quick answers