The two are separate instruments answering separate questions, and confusing them is the most common way to arrive at a permit desk unprepared.
A subdivision plat is about dividing land. A development plat is about building on it — Sec. 42-22 attaches to "development of property through the new construction or enlargement of any exterior dimension of any building, structure or improvement." No division of land need be involved at all.
Neither substitutes for the other. A project that divides a tract and builds on it can require both.
This requirement reaches the ETJ on its face. Sec. 42-22 applies "within the city or its extraterritorial jurisdiction," without the city-limits restriction that narrows several other provisions of Chapter 42 — Sec. 42-188’s access rules, for example, apply mostly inside the city only. Do not carry an ETJ assumption from one section to another.
Sec. 42-22 lists six categories of development that do not require a plat. Two of them carry conditions that decide most real cases; the other four are flat.
| Exempt | Conditions |
|---|---|
| Central business district | None stated — buildings, structures and improvements within it |
| Small alterations | No more than 100 sq ft of added exterior square footage AND no encroachment into the building line requirement. Includes enclosing an existing canopy or porte-cochere. An encroachment authorized by Sec. 42-151 does not count. |
| Detached single-family unit or enlargement | Must meet Article III requirements, and sit on a lot that is part of and complies with a recorded subdivision plat — or an unrecorded plat recognised for property conveyance |
| Parking lot or expansion | None stated |
| Retaining wall, masonry wall or fence | Under eight feet high |
| Temporary classroom building | At a public school facility |
Sec. 42-22(1) through (6). The two conditional exemptions are conjunctive — every stated condition must hold.
Development of property through the new construction or enlargement of any exterior dimension of any building, structure or improvement within the city or its extraterritorial jurisdiction shall require a development plat, except that the following types of development shall be exempt from this requirement: (1) Buildings, structures or improvements within the central business district; (2) Alterations to any building or improvement, including enclosing an existing canopy or porte-cochere, that do not increase the exterior square footage by more than 100 square feet and that do not result in an encroachment into the building line requirement.
Sec. 42-46 asks for four things, and the second and third carry most of the work.
A sealed survey. Certified by a Texas registered professional land surveyor, showing the location of every existing building, structure or improvement; every easement and right-of-way within or abutting the boundary, tied to a street intersection or landmark; and the dimensions of any sidewalk, alley, square, park or other part intended for dedication to public use. Usefully, the section says the survey does not have to be recent, so long as it illustrates all contiguous property under one ownership or common control — an existing survey may serve.
A site plan that reaches outside Chapter 42. It must show proposed and existing buildings, driveways, stairways, fences and adjacent roadways, and then demonstrate compliance with four other parts of the Code: parking under Chapter 26, landscaping under Chapter 33, bulk container location and screening under Chapter 39 Article VI, and any gang mailboxes or cluster box units built in the public street under Sec. 40-13. A development plat application is where those separate requirements converge on one drawing.
The development plat is one of only two instruments the director may approve without a commission meeting — Sec. 42-70 grants that authority for Class I plats and development plats alone. Sec. 42-53(d) then gives the director ten days from a complete application to approve it or refer it to the commission.
If it reaches the commission, Sec. 42-75 governs. The commission may defer to its next regular meeting, but not more than 30 days from the date of initial commission consideration. That measurement point differs from the equivalent rule for subdivision plats, where Sec. 42-72, 42-73 and 42-74 run the same 30 days from the filing date — a development plat’s deferral clock therefore starts later and gives more room.
Duration is the other place a development plat stands apart. Under Sec. 42-80(c) its approval is valid until the completion of the project it was approved for. There is no 12-month expiry, and so no extension request to diary.
This is how the code reads; confirm with the city — or ask a builder who's actually pulled this permit in Houston. The authoritative text is the Houston Code of Ordinances; permitting questions go to Houston Permitting Center.