Manufactured-home under-floor duct scope

Mobile Home Ductwork Replacement Cost Calculator (2026)

Estimate replacement of the main under-home trunk, crossover connections, register boots, supports, insulation, and belly closure without hiding moisture or pest remediation inside one number.

Direct answer

Mobile home ductwork replacement often costs about $3,500-$10,000. A double-wide crossover, work through damaged belly material, wet insulation, contaminated ducts, failed boots, or plenum reconstruction can push the project higher. For conventional attic, crawl-space, or basement systems, use the standard ductwork replacement calculator.

Mobile Home Duct Replacement Cost by Scope

Work item	Planning allowance	What must be defined
Main under-home trunk	$2,500-$6,500	Length, material, supports, furnace plenum transition, takeoffs, sealing, and access.
Double-wide crossover connection	$500-$1,800	Correct size, protected route, supports, sealed connections, and belly closure.
Register boots and branch connections	$150-$450 each	Boot condition, floor opening, collar, branch length, support, sealing, and register fit.
Belly wrap or bottom-board restoration	$500-$2,500+	Patch versus broad restoration, insulation replacement, fastening, and weather-tight closure.

Inspect before pricing

Four Conditions That Change the Job

Belly access: intact material may need careful openings and sealed patches; broad deterioration is a separate restoration scope.
Crossover ducts: size, route, ground clearance, supports, insulation, and protection matter more than a generic flex-duct allowance.
Moisture or pests: correct the source and define cleanup responsibility before new ducts conceal the area.
Furnace and boots: verify the plenum, collars, floor boots, return path, combustion safety, and equipment compatibility.

Do Not Bundle Unknown Remediation

A duct contractor quote should not silently promise mold, sewage, asbestos, structural, or pest remediation. Ask which conditions stop work, who diagnoses them, and how a change order will be approved. Photograph the opened area before it is closed.

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Quote Acceptance Checklist

Sketch of trunk, branches, crossover, boots, return path, and furnace connection
Material sizes, insulation, vapor barrier, supports, joint-sealing method, and clearances
Responsibility for skirting, belly openings, old material, cleanup, and closure
Written exclusions for moisture, contamination, pests, asbestos, and structural repair
Final airflow, static-pressure, connection, closure, and visual documentation

Repair, Seal, or Replace?

Use air duct repair for one dry, accessible damaged connection; use duct sealing for otherwise sound ducts with verified leakage; use this page when the under-home trunk, crossover, or multiple boots have widespread physical failure.

FAQ

How much does it cost to replace ductwork in a mobile home?

A mobile or manufactured home duct replacement commonly plans around $3,500-$10,000, while double-wide crossovers, difficult belly access, damaged boots, moisture, pests, and broad bottom-board restoration can raise the total. An inspection is needed to separate HVAC work from remediation or structural work.

Is mobile home ductwork different from conventional house ductwork?

Often, yes. Many mobile homes use an under-floor trunk connected to register boots, and multi-section homes may use crossover ducts. Access through skirting or belly material, furnace connections, supports, moisture, and bottom-board restoration create a different job.

Should a damaged crossover duct be repaired or replaced?

A localized, dry defect may be repairable, but crushed, torn, contaminated, wet, poorly sized, or repeatedly disconnected crossover material usually needs replacement. The quote should show size, route, supports, insulation, sealing, and protection.

Does duct replacement include belly-board repair?

Not automatically. Require the proposal to state who opens and closes the belly material, what insulation is restored, which repair material is used, and whether broad deterioration is excluded.

How should new mobile home ducts be verified?

Ask for visual documentation, secure supports and connections, sealed boots and plenums, a closed bottom board, clean registers, system airflow and static-pressure checks, and leakage testing when included in the scope.

Methodology

The estimator models a manufactured-home duct job from home length, section count, under-home access, register boots, crossover work, observed condition, and belly restoration. It intentionally excludes equipment and unknown remediation. Compare at least three inspection-based scopes. Last updated September 29, 2026.