Air-duct replacement cost in Luxembourg (2026)

A €1 350 replacement at 17 % TVA comes to €1 579,50 all-in. When embedded in a qualifying renovation of a principal residence more than 10 years old, the 3 % super-reduced rate can apply — a €189 saving on a €1 350 net fee — provided the contractor is VAT-registered and the overall renovation invoice meets the threshold.

Why the spread is this wide:

• A single-branch swap is a half-day job with minimal disruption; a house re-trunk is a multi-day intervention that often coincides with ceiling or floor work
• Rigid galvanised steel costs more per metre but lasts 25+ years and delivers better airflow efficiency — often the right choice in high-end renovations
• Access drives labour disproportionately: ducts above plasterboard ceilings are fast; runs through stone walls or tight attics double the time per metre

Linear-metre pricing (materials + fitting):

• Flexible insulated duct (Ø 125/150 mm): €18–€32/m
• Semi-rigid aluminium (Ø 75/90 mm, used for compact CMV loops): €28–€48/m
• Rigid galvanised steel (commercial-grade): €45–€85/m
• Plenum boxes and diffusers: €50–€120 each

The single biggest lever on a replacement quote is the duct type. Flexible insulated duct is cheaper to buy and install; rigid galvanised steel costs more but delivers better long-term performance.

Flexible insulated duct.

• Polymer or aluminium-foil inner liner with a fibreglass insulation blanket and outer jacket
• Diameter typically 125 mm or 150 mm for residential CMV
• Material cost €8–€18 per metre; installed rate €18–€32/m
• Fast to install, tolerates bends, but airflow loss per metre is roughly 2–3× that of smooth rigid duct
• Typical service life 10–15 years; inner liner develops pinholes and roughens over time
• Suitable for retrofit work in existing flats where routing has to thread through existing ceilings

Rigid galvanised steel.

• Smooth-bore with minimal airflow loss
• Sections with mechanical or slip-and-drive joints, sealed with mastic
• Material cost €22–€45 per metre; installed rate €45–€85/m
• Slower to install but dimensionally stable; supports higher throughputs
• Service life 25+ years
• Suitable for new builds and deep renovations where the trunk can be planned and run before ceilings close

Hybrid approach. Many Luxembourg installers use rigid steel for the main trunk lines (higher airflow, durability) and short flexible tail-outs to individual vents (easier to dress to the final vent position). This is usually the best value — rigid for 70 % of the length, flex for the final metre to each vent.

The three decisions that drive the type choice:

• Renovation depth. Full gut renovation → rigid trunk. Single-run repair → flex.
• Service life expectation. Owner for 20+ years → rigid. Rental or short-term hold → flex.
• Acoustic sensitivity. High-spec owner-occupied homes in Belair or Kirchberg often benefit from rigid + mineral-wool wrap for absolutely silent operation — material budget €8–€15/m higher.

After the duct-type decision, six drivers account for almost the entire gap between €500 and €2 050.

• Total replacement length. A 6 m run is a half-day; a 60 m full-house network is 3 days. Base fee covers mobilisation; the metre-rate does the rest.
• Diameter and system airflow target. A CMV designed for a large family home might use Ø 160 mm main trunks stepping down to Ø 100 mm tails — larger diameters increase both material and support hardware.
• Access route. Ducts visible in a utility corridor are fast. Runs above plasterboard ceilings with existing hatches are fast. Runs that need new hatches cut in plaster, or that thread through stone walls (typical in Grund or older Esch properties), slow the work and add hatches, core drills and finishing.
• Demolition of the old ductwork. Removing a damaged flex is cheap. Cutting out embedded steel is a skilled job — expect €80–€200 per 10 m of removal in addition to replacement.
• Disposal. Insulated duct and fibreglass off-cuts need commercial-waste disposal; €50–€150 for a flat, €100–€250 for a house.
• Coordination with other trades. Replacements timed with a kitchen or bathroom renovation are cheaper because access is already open. Standalone replacements — where the duct failure is acute and can't wait — cost more because of access-preparation overhead.

Where the biggest surprises come from. Trunk lines running through structural floors between levels in older Luxembourg-Ville townhouses often turn out to be cast-iron or lead-lined exhausts from earlier eras. Modern sleeves fit through them, but tolerance is tight and the technician may need a specialist helper — budget an extra €180–€350 of labour if this is likely.

Where you save. Rigid trunk lines installed in an accessible basement or technical room of a post-2010 house take a day of two-person labour; the same work in a difficult attic takes two days.

Replacement is not automatic — a reasonable repair on a flex duct often lasts 5 to 8 further years. The decision turns on four signals.

Replace when:

• Multiple leaks or pinholes along the same run, especially on flex duct older than 10 years — repairing one leak buys months, not years
• Crushed or kinked sections where the duct diameter has reduced by more than 25 % — airflow loss cannot be recovered without removal
• Mould growth inside the duct that cannot be cleaned off — fibreglass insulation that has absorbed moisture is a replacement case
• Rodent contamination through a breach — complete replacement of the affected run plus sealing the entry point
• Energy-efficiency upgrade — a 15-year-old flex system replaced with rigid steel at a major renovation improves fan energy use by 15–25 %

Repair when:

• Single localised tear or connection failure under 10 years into the system's life
• Damaged insulation on an otherwise intact inner liner — re-wrap without replacing the core
• Connection slip at a flange or junction box — reseal with mastic tape and mechanical collar
• Noise from a loose section — rebracket rather than replace

The repair pricing reality check.

• Single-point flex repair: €120–€280
• Insulation re-wrap over 4–6 m: €160–€320
• New flange or junction: €80–€180

The decision test.

• If the repair is under 25 % of the replacement cost and the system is under 10 years old → repair
• If the repair is over 50 % of the replacement cost → replace
• Between those thresholds — ask the technician for a five-year scenario: what's likely to fail next, and at what cost

What the inspection should produce.

• Photographs of the damaged section inside the duct using the inspection camera
• Written note on the cause (mechanical damage, age, rodent, condensation)
• Written recommendation with two options (repair vs replace) and their respective costs
• A timeline — "this can wait 6 months" or "this needs 30-day attention"

Unlike pure cleaning, duct replacement is renovation work. The TVA rules shift.

Standard 17 %. Applies to:

• Standalone replacement on a rental property
• Replacement in a commercial or industrial space
• Replacement in a private home that is not the owner's principal residence
• Replacement in a home under 10 years old
• Emergency replacement invoiced as a separate job

Super-reduced 3 %. Applies to:

• Replacement bundled into a qualifying renovation of a principal residence more than 10 years old
• Work carried out by a VAT-registered Luxembourg contractor
• Total renovation value meeting the Administration de l'Enregistrement et des Domaines thresholds
• Owner having held the property for the required period and genuinely using it as primary residence

The 3 % rate saves €168 on a €1 200 net invoice versus the 17 % rate — meaningful on full-house re-trunk jobs.

The documentation that supports the 3 % rate:

• Copy of the title deed or most recent acte de propriété
• Certificat de résidence from the commune showing the property is the owner's primary address
• Receipts for the broader renovation project (tiler, electrician, plumber)
• The contractor's VAT number on the invoice

The contractor decides — not the client. Only the contractor can invoice at 3 %. If you want that rate, raise the question at quote stage, not at invoice. The contractor will confirm eligibility by checking their own books with the tax office.

The declared-labour point. Only registered entreprises can apply either VAT rate. An unregistered handyman offering cash-in-hand work leaves you with no TVA trail, no warranty and no path to resale documentation. On a renovation that will eventually feed into a property sale, that paperwork gap typically costs €1 000–€3 000 in a negotiated reduction from the buyer's agent.

Keep for ten years:

• Quote with line-by-line scope
• Invoice with full TVA treatment
• Photos of the new installation
• Commissioning note from the installer
• Warranty card for materials (typical 5-year warranty on rigid steel; 2-year on flex)

A duct replacement rarely lives alone. Pairing it with adjacent work cuts costs and restores the house faster.

Natural pairings.

• Bathroom renovation. Extract ductwork from the bathroom usually runs in the ceiling void. Replace both ceiling and duct in one operation — save €200–€400 on disruption costs.
• Kitchen renovation. The kitchen extract is typically the most heavily-used run in a home. A new hood with modern airflow benefits from a fresh duct — pair with the kitchen installation.
• Heat-pump or AC installation. Multi-split refrigerant lines and duct replacements often need the same inspection hatches. Coordinate to open once.
• Floor refinishing or ceiling repainting. If work opens access to routes you couldn't reach before, run it then.

Scheduling windows.

• Spring (Mar–May) — installer schedules are busy but planning is doable. Order ducts 4 to 6 weeks ahead.
• Summer (Jun–Aug) — heat-pump and AC installers are at peak; duct-specialists are often second priority. Book a duct-focused firm rather than a general HVAC installer.
• Autumn (Sep–Nov) — best season for coordinated work with other trades. Contractors have capacity and the weather supports outdoor hatch operations.
• Winter (Dec–Feb) — off-season discounts of 8–12 % on labour are common. Avoid if work requires outdoor ladder access on icy days.

Apartment context. Replacement work in a Luxembourg apartment block touches common parts when the trunk goes through a communal stack. The syndic must approve. Timeline:

• Pre-consultation — 1 week
• Written request with installer drawings — 2 to 3 weeks
• Vote at next AG or written circular — 4 to 8 weeks

Don't sign with an installer before you have the syndic approval in hand. Plan the install for 2–3 months out.

Disruption to residents.

• Single-branch swap: 2–3 hours in one room
• Multi-branch swap: half a day to a day across 2–4 rooms
• Full network swap: 2–3 days; expect kitchen and bathroom ventilation to be offline for one night
• Dust management — HEPA-filtered vacuums and plastic sheeting are standard in declared firms; expect the rooms to be useable again the same evening

The hand-back checklist.

• Commissioning-run confirmed at each vent
• Airflow measurement at each vent (m³/h) recorded
• Photos of every new section
• Written acceptance signed by both parties
• Fixing faults under the handover checklist before final payment — never pay in full on the day

A clean replacement is invisible in daily life — quiet air, better throughput, lower fan energy. A poor replacement shows up within weeks as noise, reduced flow and repeat call-outs.

Red flags in a replacement quote:

• No distinction between flex and rigid — forces you into whichever is cheaper for the installer
• No diameters specified — the quote becomes a fixed-cost fiction
• "Disposal included, no further charges" without specifying volume — the bill can spike on the day
• "We'll match the existing" without inspecting — matching is often wrong and leads to rework
• A warranty shorter than 2 years on materials — below market standard
• Cash-only discount — no TVA trail, no warranty path

Hidden costs often revealed on the day:

• Patching of original plaster after hatch creation — €80–€200
• Repainting of ceiling after access work — €100–€300
• Replacement of one vent diffuser not originally scoped — €40–€120
• Additional acoustic insulation at a discovered noise hotspot — €80–€250
• Structural-support reinforcement under new rigid trunk — €120–€350
• Commissioning test flagging another fault unrelated to the replacement — billed separately, €80–€180

Long-term value drivers:

• Rigid trunk with short flex tails is the best-value hybrid for a 20-year horizon
• Annual filter service on the CMV or HVAC cuts duct contamination, extending the cycle between replacements
• Keep the as-built drawings — the next intervention is cheaper when the installer knows what's behind the plasterboard
• Document the system at commissioning — photos, measurements, brand references — this is the single best tool to negotiate against a future inflated quote

The 10-year total cost.

• Flex-only system with annual service: €1 400–€1 800 all-in
• Hybrid rigid-trunk system with annual service: €2 200–€2 800 all-in (but one fewer replacement cycle)
• DIY-maintained cash-payment system: higher repair rates, no warranty, repeated visits — often the most expensive option over a decade

A replacement done right adds value that survives resale. A replacement done cheaply shows up in the buyer's inspection report.

Three quotes on an identical brief can land at €800, €1 400 and €1 950. The spread reflects scope assumptions more than margin.

The brief pack to send each provider:

• Floor plan with current duct routes marked
• Photographs of the visible sections and any damaged areas
• Current system details — simple-flow or double-flux, exchanger model if double-flux
• Reason for replacement (age, damage, energy upgrade)
• Desired outcome — full replacement, partial, or hybrid rigid + flex
• Timeline constraint — coordination with other trades
• Copropriété règlement if applicable

The eight checks on the returned quotes:

• Material spec — rigid, flex or hybrid, with diameters
• Linear-metre rate for each material class
• Base fee covering mobilisation and commissioning
• Demolition and disposal as named line items
• Access-work line items — hatches, core drills, patching
• Warranty terms — material and labour separately, minimum 2 years
• TVA handling — 17 % standard or 3 % super-reduced if bundled; same treatment across all three
• Commissioning deliverables — airflow readings, as-built drawings, photos

Common reasons for wide spreads:

• One quote is fully flex, another is full rigid — rebalance to compare like-for-like
• One quote uses Ø 125 mm, another Ø 150 mm — diameter matters for airflow
• One quote includes reinstatement of plaster; another silently excludes it
• One quote assumes the client disposes of waste; another includes it

Narrowing the gap.

• Ask each provider to quote the same hybrid configuration — 70 % rigid trunk, 30 % flex tails — to get comparable numbers
• Specify exactly the diameters you want quoted on
• Confirm warranty terms in writing, not on the phone
• Get all three invoices at the same TVA rate

Providers on the same brief land within ±15 % of each other. A 30 %-below outlier is almost always a cash-in-hand offer; a 30 %-above outlier usually includes premium materials or a longer warranty — worth evaluating before ruling it out.