What Can I Build on My Lot? (Buildable Area)

The City of Houston has no zoning ordinance. Two things take its place. The first is Chapter 42 of the City's Code of Ordinances (subdivisions, developments and platting), which sets minimum building lines along streets and requires every plat to show them. The second is private deed restrictions recorded for the subdivision, which are enforced by the neighborhood or through the City's deed-restriction process. Chapter 42 says its building lines are minimums, and where a deed restriction asks for a greater setback, the deed restriction controls.

What the City's own plat-note guide shows for a single-family lot along a street (examples of what you may see on a plat, not a table to apply to your lot):

• A 10 ft building line for the house with a 20 ft line for a garage face parallel to the street (Chapter 42, Sec. 42-156(c)), or 10 ft with a 19 ft line for a garage facing the street (Sec. 42-157(b)). Both need the plat to carry a "typical lot layout" and the right plat notes.
• Along a major thoroughfare, a single-family lot that backs onto the road can have a 10 ft rear building line if it meets Sec. 42-152(b), and 25 ft otherwise.
• A 25 ft front line for a single-family lot on a collector street is the City's baseline in the ordinance text (Sec. 42-156(a)), and 25 ft is also a very common front line on older plats and in deed restrictions.

Chapter 42 mostly sets lines along streets. Side and rear setbacks between neighbors usually come from the plat, easements, deed restrictions and the building and fire codes. Because the section numbers and exceptions change as the ordinance is amended, read the building line shown on your own recorded plat, then your deed restrictions, and ask the Houston Permitting Center if they conflict. The default numbers in this tool (25 ft front, 5 ft sides, 10 ft rear, 10 ft rear easement) are examples only. Outside the City of Houston, the plat, deed restrictions and your own city or county rules apply.

Fire code can also limit how close a wall can sit to a lot line even when no setback exists. The IRC asks for fire-rated walls and limits openings when the wall is within 5 ft of the lot line (IRC R302.1 in the 2021 edition), so check with your building department.

The tool starts with your lot outline (a rectangle, or a straight-sided shape with a different back width). It moves each edge inward by the larger of its building line and its easement, and keeps what is left. That is the buildable footprint. If you enter a coverage limit, the footprint is capped at that percent of the lot area.

Maximum house size is the footprint times the number of stories, less the garage. Stories are counted at 10 ft each, plus a 1.5 ft raised floor and about 7 ft of roof, and compared with your height limit. The sample house is a simple rectangle sized to your target living area divided by the number of stories. It is placed in the buildable area next to the garage if you chose one. If the rectangle cannot fit, a red block shows how much is over. A story that rises above the height limit turns red.

The garage is a single story, 22 ft deep. A front-facing garage sits at the garage face setback you enter. A side-entry garage is turned so its door faces the side yard. A detached garage sits at the back, with 5 ft kept between it and the house.

• Height: the City has no zoning height limit for houses, so any limit usually comes from your deed restrictions, which often say 35 ft or a number of stories and may measure to the peak or to the middle of the roof. This tool measures to the peak.
• Coverage: Chapter 42 does not set a general building coverage cap for an ordinary single-family lot. Deed restrictions sometimes do, and drainage and detention rules can limit paving and roofs. Ask the Houston Permitting Center what applies to your lot.
• Flood: a lot in a mapped floodplain may need the lowest floor raised above the street, which changes the height. Check the City's Floodplain Management Office and the Houston Property Research Guide.
• Corner lots: street-side lines and visibility triangles apply on corner lots. This tool does not draw them.

A planning aid, not a survey or a code review. Confirm lines, easements and heights with your plat, deed restrictions and the permitting office before you design or buy.

• City of Houston Planning and Development, Ordinance Notes for Platting (October 2024): building line plat notes for Sec. 42-150, 42-156 and 42-157
• Houston Code of Ordinances, Chapter 42, Subdivisions, Developments and Platting (Article III, Division 3, Building Lines)
• City of Houston Planning, Development Regulations (Chapter 42)
• City of Houston Legal Department, deed restrictions
• 2021 International Residential Code, Chapter 3 (R302 fire-resistant construction)