In July, the D.C. Office of Planning submitted a draft of its new zoning regulations, following a six-year review. Much of the media attention in response focused on parking issues but, notably, the review made few significant changes to the city’s residential zoning code. This suggests that the Office of Planning values the character of the District’s neighborhoods and its mix of low- and high-density residential units.

Unfortunately our experience, and subsequent research, shows that, in practice, the Board of Zoning Adjustment (BZA) — the body that grants variances to the code — serve as a large developers’ loophole, undermining the District’s longstanding preference for maintaining the look and feel of its communities.

We attended the July Advisory Neighborhood Commission (ANC) meeting in Columbia Heights to oppose a developer’s effort to secure the ANC’s endorsement of his request for a zoning variance. The developer was seeking to alter a single-family structure to create four condos on a lot that is zoned for a maximum of three.

To be clear, we support development and the reinvigoration that has taken place throughout much of the District over the past 10 years. Higher-density residential buildings are welcome, but they can and should be accommodated within current zoning rules. In the case above, the code already permitted the conversion of the single-family unit into three condos. It is unclear why a fourth was necessary — beyond the developer’s stated goal of increasing his profits.

The trouble with zoning variances is that they circumvent the rules by which the city manages development. Because fixed rules cannot apply to all situations, zoning variances should be allowed in exceptional circumstances. Unchecked, however, they can create a significant burden on our communities, for three reasons:

Density: The zoning code sets aside areas for low-density development to accommodate families in the urban center. Certain variances create higher densities than envisioned, reducing available street parking, overloading infrastructure such as sewer lines (a cause of flooded basements) and eroding the appeal of single-family neighborhoods.

Affordable housing: Excessive zoning variances can distort the real estate market and artificially drive housing prices higher. A sophisticated investor, reasonably sure of receiving a variance to convert a single-family home into a multi-unit apartment, will outbid other potential home buyers.

Aesthetics: Often developers will tear through the roof of a rowhouse to accommodate a third or fourth unit, destroying the architectural cohesion of townhouse rows and their historical facades, a defining characteristic of many D.C. neighborhoods.

The BZA’s mandate is to review variance requests using a three-pronged test to ensure that a variance is truly necessary and neither harms the public good nor undermines the overall zoning code. For residentially zoned areas, variance requests are typically for permission to add units beyond the limits set in the code.

That’s why in isolation, one developer’s request for ANC support for one extra unit may not seem troubling. However, this anecdote is indicative of a disturbing trend in Washington’s hot real estate market.

Our suspicions about the bigger picture prompted us to request data from the Office of Planning on all the variances allowed by the zoning panel. The figures show that applications for residential variances have increased steadily over the past several years, doubling between 2006 and 2013. And, astonishingly, the BZA has approved 95 percent of those requests, sometimes over the objection of the Office of Planning and the local ANC. These data demonstrate that the BZA is making the approval of variance requests the rule, not the exception, to the detriment of our communities.

We fear that the approval rate is so high because of the coziness between the zoning board and real estate community, at least in part. The former board chair, for example, is now a lawyer who represents investors seeking variances, work she is allowed to do because the “cooling off” period after leaving the board is a mere six months.

If the District has confidence in its residential zoning code — which, after all, city planners have just reaffirmed after a painstaking review — then zoning variances should be rare. The high rate of approval indicates that the process needs reform. For starters, we suggest a longer cooling-off period before former members can do business with the board, an enhanced review process to ensure strict and consistent application of the zoning board’s mandate, a broader definition of “detriment to the public good” that includes characteristics such as architectural beauty and livability, and public reporting of aggregate data on variances so patterns like the one we discovered are immediately visible to all.

The writers are homeowners in the District’s Columbia Heights neighborhood.