Building codes
Most US houses are built under a local version of the International Residential Code (IRC), published by the International Code Council. States and cities adopt an edition, often with their own changes, so your local limit can differ from the model code. Our pages cite the 2021 IRC, mainly:
- Chapter 3, building planning: stairs (R311.7), emergency escape windows (R310) and the space around bathroom fixtures (R307).
- Chapter 8, roof and ceiling framing, including the rafter span tables (R802).
- Chapter 27, plumbing fixtures.
The official code website limits automated access, so some figures are cited from city and state copies of the same IRC sections. Where that is the case, the page links to that copy.
Accessibility
Accessible heights and clearances come from the 2010 ADA Standards for Accessible Design (U.S. Access Board). They apply to public buildings; in a private home they are a useful guide, not a requirement.
Guides and makers
Deck stairs follow the American Wood Council’s Prescriptive Residential Wood Deck Construction Guide (DCA 6). Room air conditioner sizes follow the ENERGY STAR sizing chart. Product sizes come from the makers’ own size charts and spec sheets, and from store listings where a maker doesn’t publish them.
Before you build
Call or check the website of your local building department for the code edition and amendments that apply to you, and whether your project needs a permit. Follow the maker’s installation instructions for any product.