Building codes by trade and place
CodeX is a code reference for electricians, plumbers, HVAC technicians and building inspectors. Ask in your own words, say where the job is, and get the sections that govern the work, each one linked to the publisher's official text.
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How much fall does a 4" sanitary pipe have to have?
Horizontal drainage piping must be installed in uniform alignment at a uniform slope. Minimum slope: 2-1/2 inches and smaller: 1/4 inch per foot (2 percent); 3 inches to 6 inches: 1/8 inch per foot (1 percent); 8 inches and larger: 1/16 inch per foot (0.5 percent). A 4-inch sanitary line therefore needs at least 1/8 inch of fall per foot under the IPC.
Open in the ICC viewerHow far apart do wall receptacles have to be?
(A) Walls: in habitable rooms no point along the floor line of any wall space may be more than 6 feet from a receptacle, and any wall space 2 feet or wider counts. (C) Countertops: a receptacle for each wall countertop space 12 inches or wider, placed so no point along the wall line is more than 24 inches from a receptacle, and not more than 20 inches above the countertop; the 2023 code no longer requires island and peninsular receptacles, but provisions for adding one must be made if none is installed. (D) Bathrooms: at least one receptacle within 3 feet of the outside edge of each basin. (E) Outdoors: one at the front and one at the back of a one-family dwelling, readily accessible from grade and not more than 6 1/2 feet above it. (F) Laundry: at least one. (G) At least one in each basement and in each garage with power, with one for each vehicle bay not more than 5 1/2 feet above the floor. (H) Hallways 10 feet or longer: at least one. (I) Foyers larger than 60 square feet: one in each wall space 3 feet or wider.
Open in the NFPA viewerHow long can a dryer vent be?
Exhaust ducts for domestic dryers must have a smooth interior finish, be metal at least 0.016 inch thick, and be 4 inches nominal in diameter. They are supported at 4-foot intervals, with the insert end of each section pointing in the direction of airflow and fasteners protruding no more than 1/8 inch into the duct. The transition duct from the dryer must be a single length listed to UL 2158A, not more than 8 feet long, and not concealed within construction. Maximum length is 35 feet from the transition duct connection to the outlet terminal, reduced for fittings by Table 504.9.4.1: 2 feet 6 inches for a 4-inch-radius mitered 45-degree elbow and 5 feet for a 4-inch-radius mitered 90-degree elbow, with smaller deductions for longer-radius smooth elbows. Alternatively the length is set by the dryer manufacturer's installation instructions, a copy of which goes to the code official (504.9.4.2).
Open in the ICC viewerHow high does a guard have to be?
Required guards must be at least 42 inches high, measured vertically from the adjacent walking surface, from the line connecting the leading edges of the tread nosings on stairs, or from the ramp surface. In Group R-3 occupancies not more than three stories above grade, and within individual dwelling units in Group R-2 not more than three stories above grade with separate means of egress, guards may be 36 inches high. In Group R-3 and within individual dwelling units in Group R-2, guards on the open sides of stairs may be 34 inches high, measured from the line of the tread nosings, and 34 to 38 inches where the top of the guard serves as the handrail.
Open in the ICC viewerThe dropdown above the question box decides what a question does.
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The matching sections of the code book, from the library on the phone. Type a question the way you would say it, or a section number. Nothing leaves the device.
Uses your AI provider
A short written answer built only from those sections. Every requirement is cited, like [§704.1], and each citation opens the section so you can check it.
Brand and part number
Type a brand and a model or part number. CodeX searches the manufacturer's own site for the installation instructions and the parts list, and you can save them to the phone.
Each profession is its own silo: its code book, its example questions and its own job history. Switch from the top of the screen.
NEC 2023 143 sections
Install and maintain wiring, panels and lighting systems, strictly following the National Electrical Code (NEC) to prevent fire and shock hazards.
One reference book everywhere, with a note on the edition your state enforces where CodeX knows it.
IPC 2021 100 sections or UPC 2021 64 sections
Design and assemble water supply, sanitary drainage and gas piping systems, complying with regional plumbing codes to keep drinking water safe and prevent contamination and gas leaks.
The book follows the place: CodeX uses the one the state, county or city adopted.
IMC 2021 73 sections
Set up heating, ventilation, air conditioning and refrigeration equipment. Mechanical and fuel-gas codes govern the work: fuel safety, exhaust and refrigerant handling.
One reference book everywhere, with a note on the edition your state enforces where CodeX knows it.
IBC 2021 69 sections
Review structural, electrical and plumbing work on site, using the International Building Code (IBC) and local ordinances to approve or reject active construction.
One reference book everywhere, with a note on the edition your state enforces where CodeX knows it.
Library not in CodeX yet
Install and safety-test vertical transport systems, in strict adherence to specialized elevator and electrical safety codes.
Governed by ASME A17.1 / CSA B44 and NEC Article 620. You can choose the profession now; the library comes later.
Pick the state, county or city, or use your location once. Plumbers get the IPC or the UPC by what the place adopted. Electricians see which NEC edition the state enforces.
The code library ships inside the app. Save the adopted code, local amendments or an installation guide to the phone for the crawl space and the basement.
Tap the mic and ask. The answer is read aloud, and you can say "explain", "yes", "no" or "done" with your hands full.
A question stays open until you mark it done, then becomes one line in recent activity. Tuesday's measurement is one tap away on Friday.
Utility maps, county GIS and the 811 locate service for the place you chose, next to the code.
For plumbers, a materials quick reference for the place: what is allowed for the sewer, the drain and the water service, with the local amendments CodeX has on record.
The section text in CodeX is our own summary with the governing numbers. It is not the official code text, and it can be incomplete, out of date or wrong. States, counties and cities adopt different editions and amend them, and a written answer comes from an AI model that can misapply a section even when it cites one.
That is why every section links to the publisher's own viewer, and why the professional remains responsible for following the code as adopted and enforced where the work is. Confirm with the authority having jurisdiction. The full terms are in the license agreement.
CodeX is in beta on iPhone and Android. Tell us your trade and your phone, and we will write back when there is a build for you.