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Building Owners, Watch for Hidden Costs Under the Sidewalk

In 2007, the San Francisco Board of Supervisors made a little change to the city’s public works code that has been affecting our clients who own downtown buildings. Many of these buildings were constructed with small spaces extending beneath the sidewalk. These spaces may be handy to have for storage or other uses, but they can be a hassle as well, because they typically develop leaks that are troublesome to repair. Now there’s another hitch. Many property owners assume these spaces belong to the building, but technically, since property lines end at the building exterior, the City of San Francisco actually owns everything under the sidewalk. And now, as owners undertake repairs to the leaks, the City is taking the opportunity to charge rent.

When leaks occur, building owners have two options. The sidewalks above these spaces have what is known as “split slab” construction. This consists of a topping slab, which forms the sidewalk surface, and a structural slab. A waterproofing membrane is sandwiched in between these two slabs. (see historic sidewalk drawing titled “sidewalk vault, lower right corner) The membrane usually fails at perimeter locations or when a penetration is made for an electrical conduit or pipe, and that’s when water starts dripping into the space below. Building owners sometimes use a deck coating on the sidewalk to fix the leak—basically, this is a thick, surface-applied membrane. This may work for a period of time, but it requires frequent reapplication, because people are constantly tromping on it.

The longer-lasting solution is to remove the sidewalk, replace the waterproofing membrane, and cover it with a new sidewalk. (See photo of new membrane being installed over structural slab) The downside: the construction tends to be disruptive for building occupants. For downtown sidewalks, there is a standard color and finish for sidewalks that must be complied with.

In some of the recent sidewalk projects we’ve been involved with—projects involving removal of the sidewalk and replacement of the old membrane—we’ve found that the City is now interested in more than just making sure the sidewalk is properly reinstalled.

In 2007, the Board of Supervisors passed Ordinance 165-07, which clarifies that “the public right-of-way occupancy assessment fee for minor sidewalk encroachments applies to specified building permits and all subsidewalk basements.” Rent was $3.31/sf/year for 2010. Payment is assessed when the permit for the sidewalk work is pulled. Owners will be informed of future rent, now that it is recorded at the City.

Given the cash-strapped state of city budgets these days, it’s not surprising that any source of revenue is welcome. But not everyone is aware of the ordinance yet. That’s why, to get the word out, we’re rewriting the refrain to the famous 1964 pop song by the Drifters:

(Under the sidewalk) if the membrane is weak
(Under the sidewalk) we’ll be fixing the leak
(Under the sidewalk) while we’re mixing cement
(Under the sidewalk) they’ll be charging you rent

Click here to view the Ordinance Assessment.