What is the 2026 cost range for a interior conversion scope adu in Houston?

$85,500-$180,500, with the median landing near $133,000. The range reflects finish tier and layout complexity within the interior conversion scope; the Houston labor multiplier of 0.95× vs national median is baked in.

How long does a interior conversion scope adu take in Houston?

14-20 weeks of on-site construction for the interior conversion scope, plus 3-8 weeks of permit review in Houston if the scope requires a permit. Cosmetic-only refreshes often skip permits; anything touching plumbing, electrical, or structural does not.

What is the single biggest budget-overrun risk for this scope?

Existing slab without a vapor barrier — vapor-pressure moisture leads to flooring failure and mold if not re-poured or sealed. Adds $4-8K.

ADU — Interior conversion Cost in Houston, 2026

Low

$86K

$85,500

Median

$133K

$133,000

High

$181K

$180,500

Scope timeline: 14-20 weeksHouston permit window: 3-8 weeksUpdated 2026-04-24

Why interior conversion × Houston produces this band

A interior conversion scope for a adu in Houston combines two price levers: scope and metro labor rates. Interior-conversion ADUs repurpose an existing enclosed space (attached garage, basement) without adding foundation or framing footprint. Faster and cheaper than a detached build. Against the national median remodel labor rate, Houston runs 5% below the national median — so the interior conversion band comes in 50% below the mid-range, then scales 5% below the national median on top of that. Permit timelines for residential work in Houston typically run 3-8 weeks, which is the window you plan your design and decision sequence against. This page gives you the actual 2026 Houston bands for this exact combination, plus the three cost drivers Baily asks about first when scoping the project live.

What drives cost for a interior conversion scope

·Insulation and conditioned-space HVAC tie-in
·Egress window cutting and well install
·Kitchen and bath rough-ins (often net-new to the space)
·Legal separation from the primary unit

What makes Houston different

Labor — Energy-industry remodel demand drives premium-finish installer availability (Memorial, River Oaks).
Labor — Hurricane-repair cycles (Harvey 2017, Beryl 2024) create periodic labor tightness.
Labor — Non-union market with strong Hispanic crew supply — bilingual coordination common.
Material — Port of Houston handles Asia-Pacific finish imports — generally competitive pricing.
Material — Flood-zone construction requires elevated utilities and waterproof-rated materials within the AE and X-shaded areas.

Houston rules that affect this scope

Houston is the largest U.S. city with no formal zoning — deed restrictions + neighborhood HOA covenants take the role of zoning.
Harris County Flood Control District requirements overlay City of Houston permits in the AE zone and below.
Wind design for coastal Harris County follows 130 mph ultimate design wind speed — affects window, roof, and envelope spec.
Sewer capacity moratoria in some infill neighborhoods affect ADU and second-unit scope.

Scope your adu with Baily.

Baily asks the eight questions that determine where your project lands inside the $86K-$181K band for Houston and hands the scoped brief to one licensed builder.

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Questions LA homeowners actually ask

$85,500-$180,500, with the median landing near $133,000. The range reflects finish tier and layout complexity within the interior conversion scope; the Houston labor multiplier of 0.95× vs national median is baked in.