How this atlas is made

Every rule, deadline, dollar figure and safety step on this site comes from an official source, and each page lists its sources at the bottom with the date we checked them. Where a page gives a number we calculated ourselves, such as a borough’s share of homes in walk-up buildings, it says so.

Which sources does the atlas use?

City agencies first. For heat, hot water and tenant complaints we rely on the Department of Housing Preservation and Development, NYC311 and the Housing Maintenance Code as compiled by the Department of Buildings. Boilers, gas piping inspections, plumbing permits and licenses come from DOB. Water, sewers, lead lines and bills come from the Department of Environmental Protection and the NYC Water Board’s rate schedule. Roof tanks come from the Health Department, and winter advice from NYC Emergency Management and FDNY.

Beyond the city, we use New York State Homes and Community Renewal for rent-stabilized tenants, the State Attorney General for co-op boards, the US Consumer Product Safety Commission for scald temperatures, the US Department of Energy and the NYC Retrofit Accelerator for steam heat, a Weil-McLain boiler manual for maker guidance, and Con Edison and National Grid for gas emergencies. Borough pages draw on City Planning’s tax-lot data (PLUTO, version 26v2) and its community district profiles.

What happens when two official sources disagree?

We pick one, say which, and explain why on the page concerned. The biggest case is gas. Some city notices list a step to take indoors before leaving. Con Edison and National Grid say to leave at once, and this site follows them: get everyone out without touching switches or phones, then call 911 and your gas utility from outside, away from the building. See gas smell. Other examples: HPD’s heat page still shows penalty amounts older than the current code, and one DEP page gives a combined water and sewer rate that does not match the Water Board’s schedule. In both cases we use the code or the schedule and note the difference, as on the water and sewer bill page.

Are the drawings and pictures real?

The drawn street on the home page and the building cross-sections are schematics. They show how a typical building of each type is laid out; they are not surveys, official maps or plans of any real address. Photos of real buildings come from Wikimedia Commons, credited on the photo credits page. Some pictures were made with an AI image tool; each one is labelled as AI-generated where it appears.

What could we not reach?

Some gaps show. Borough complaint counts aren’t published in a form we could use, so the site gives HPD’s citywide totals instead, and there are no Census tables on building age or size. Code text comes from the Housing Maintenance Code compilation that DOB publishes, which is a compilation and not the official edition. Where a DOB lookup tool is named, pages link to DOB’s own landing page for it.

How current is it?

Every source was checked on 11 November 2026, and money and rule facts carry their effective date. Rules change: the natural gas detector deadline, for one, could move. Before you act, check the agency page linked from the topic, or ask your super, the building’s management or a licensed plumber. Read about this site for who makes it.