What is "code?"
You've heard it spoken of in angry and frustrated tones...but what is it, anyway?
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There are many rules about what you can and can’t build, and there are many codes, ordinances, and statutes from federal to state to local level that form an overlapping pile of stuff that every project has to sort out.
The two major categories are “building code” and “zoning code.”
First, building code - each state adopts its own [and it can be amended by the local jurisdiction], and it is administered and interpreted by local building departments and inspectors. It covers everything about the building itself - from structure to size, from windows to stairs, from insulation to roof, to egress, fire safety, energy efficiency, etc. It also has related codes, covering everything from mechanical, plumbing, electrical, fire, environmental considerations, site, etc.
States are also required to adhere to the Americans With Disabilities Act, [ADA], passed in 1990, which is federal, and administered by the Department of Justice. Only part of the ADA actually deals with buildings, and each state must adopt those sections into their building codes. In Massachusetts, for example, it’s not called “ADA”, it’s called Massachusetts Architectural Access Board [MAAB], and there are some subtle differences between MAAB and ADA.
You’re probably catching on to the fact that there are *a lot* of things to keep straight - and it falls mostly on the shoulders of architects to do that. On more complex projects, there are teams of consultants helping keep code requirements organized, as well as engineers who are responsible for making sure things meet code in their area - electrical, plumbing, mechanical, site, fire, envelope, etc.
For this reason, architects are licensed by state, not federally. Regulations can change quite a bit across state lines, so most architects are only licensed in one state, or maybe 2 or 3. States have different licensing requirements, as well as different continuing education requirements, all to help ensure that architects are keeping up with all this code information.
Ok, now let’s talk about zoning. Zoning code, or ordinance, is written and administered at the local level - the town, city, township, etc. Not every jurisdiction has a zoning code - Houston, for example, famously doesn’t have one - but the vast majority, even small rural towns, have some form of zoning code.

Zoning code regulates land use and how a building may sit on a site. It tells you which neighborhoods you can build which kinds of buildings in, and which kinds of buildings may be adjacent to each other. This is how cities make sure that factories don’t get built right next to houses, or that bars don’t get built next to schools, but it also often prioritizes single family houses above all other types, even in denser urban environments or downtowns.
Through the use of dimensional requirements and calculations, zoning regulates the size and shape of buildings on a lot - things like setbacks, height limits, lot usage area, floor area ratio, and the like all must be calculated very carefully based on an official survey. The tighter the site, and the closer you are to trying to max out zoning, the more careful you’ll have to be with these calculations.
It’s also important to understand the nature of the jurisdiction you’re working in - some are much more relaxed than others, while some are extremely, extremely exacting. We usually work in the exacting ones!
Some jurisdictions use fewer calculations, and more visual or proportional means to regulate building shape. This is called form-based zoning, and has its advantages and disadvantages over more traditional zoning. The city of Somerville integrated form-based zoning into its recent zoning overhaul, if you’d like to take a look.
Understanding the intersection of building code and zoning code is crucial, if you’re trying to make smart financial decisions with your project.
For example, zoning might allow 75’ buildings in a certain district, but building code in Massachusetts defines a building as a “high rise” when it’s over 70’ tall [not 70’ to the floor of the top story, like most states, but 70’ to the top of the roof]. When a building is characterized as a high rise, it means lots of additional measures in the building, from pressurized stair shafts to more advanced smoke control and the like - read: more costs. If you’re only getting 5 more feet of height, and no additional usable space, but it’s going to cost you a bunch more money, you don’t actually want to max out the zoning.
There are many other codes and laws that buildings must adhere to, such as those related to affordable housing [administered through HUD], historic districts, conservation districts, ground water districts, etc etc. Depending on the location of your site, you may be dealing with federal agencies, transportation agencies, state organizations, and neighborhood groups. As you can imagine, one of the most important things you can do, when looking at a potential site for purchase and/or development, is to understand what that Venn diagram of regulations you’ll have to deal with might be. It will have a profound impact on the speed of your project, as well as its financial viability.
If you’re unfamiliar with zoning codes, read your local ordinances, go to some hearings, read the minutes, and find a good team to advise you [an architect and a zoning attorney with experience working in that jurisdiction and on the types of projects you want to do].
To increase your familiarity with building codes, understand which codes are applicable in your area and for your project types, read the code, and again, find a good team [an architect and/or a code consultant]. Look back at previous drawing sets from your previous projects and read the code summaries, ask building professionals how codes impact certain issues you’re working on, etc.
There is SO much more to say about all kinds of codes - stay tuned to this space, where I’ve got future posts queued up on how to read code, how to do a preliminary zoning analysis, etc. And always, always remember - every jurisdiction is different, and even neighboring *lots* can have different rules applied to them. Make sure you’re getting the right information, it can make or break a project!
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