How to Quote and Run a Commercial Ventilation and Extraction Installation

What you will learn

• How to run a site survey that captures all cost drivers before you price a ventilation job.
• The DW/172 airflow calculation method for commercial kitchen systems requiring 20-30 air changes per hour.
• How to structure a ventilation quote with separate material, ductwork, electrical, and commissioning lines.
• What to order first after contract award and why plant lead times of 4-8 weeks can affect your programme.
• The commissioning and balancing records you must produce for building control and environmental health sign-off.
• How to introduce a maintenance contract at handover while the customer is engaged and the system is fresh.

Commercial ventilation and extraction is one of the most technically demanding trades in building services. A project can span a simple wall-mounted fan in a takeaway kitchen to a £40,000 fully balanced supply-and-extract system for a large hotel restaurant. Either way, the job carries the same compliance obligations: the system must meet DW/172 (the Building Engineering Services Association's specification for commercial kitchen ventilation), satisfy Approved Document F of the Building Regulations, and pass inspection by building control, the environmental health officer, and sometimes the fire authority. Getting the quote right requires a proper site survey, accurate load calculations, and a clear scope of supply. Getting the installation right requires disciplined procurement, trade coordination, and thorough commissioning documentation.

Step 1: Qualify the Enquiry and Define the Scope

Not every ventilation enquiry is the same job type. Before committing to a site visit, establish which category of project you are looking at - this determines the survey scope, the compliance pathway, and the trade coordination required.

The main project types are:

• Commercial kitchen extraction - grease-laden extract requiring canopy hoods, baffle filters, fire-rated ductwork, fire dampers, and make-up air. DW/172 mandatory.
• General commercial MVHR - offices, retail, and public spaces requiring balanced mechanical ventilation with heat recovery under Approved Document F.
• Toilet and wet room extraction - typically extract-only, governed by Approved Document F Part 1.
• Industrial extraction - workshops, vehicle bays, and print rooms with contaminated or high-temperature extract streams, usually under COSHH regulations and TR40 guidance.

During qualification, ask the customer for existing drawings, the building type, approximate cooking load or occupancy, and whether the project is a new build, refurbishment of an existing system, or a like-for-like replacement. Refurbishment projects routinely cost more than the customer expects because existing ductwork may not meet current standards and may need replacing.

Step 2: Carry Out a Full Site Survey

A desk estimate is not a quote on a ventilation project. Commercial ventilation pricing depends on run lengths, duct routing, structural penetrations, plant room or roof access, and electrical supply capacity. You cannot reliably estimate any of these without visiting site.

1. Measure the kitchen or space dimensions and calculate the total volume in cubic metres (length x width x ceiling height).
2. For kitchen projects, identify the cooking load - the equipment types, heat output, and whether solid fuel appliances such as wood-fired ovens or charcoal grills are involved. These require higher extract rates than gas or electric cooking lines.
3. Walk the proposed duct route from the extract canopy to the discharge point. Note the number of bends, total run length, and any penetrations through fire compartment walls or floors that will require fire-rated ductwork and intumescent dampers.
4. Identify the make-up air entry point. Note whether a dedicated air handling unit (AHU) is required or whether natural supply is feasible given the space layout.
5. Check electrical supply capacity at the distribution board. Large inline fans draw 2-7kW; confirm whether the existing supply can support the additional load or whether a new circuit is needed.
6. Photograph everything - the proposed duct route, the discharge location, the canopy position, and the distribution board. Photographs protect you when a customer later disputes what was included in scope.

Step 3: Calculate Airflow Requirements and System Design

DW/172 and Approved Document F both specify minimum air change rates. For commercial kitchens, the standard requires 20-30 air changes per hour, with higher rates for heavy-duty cooking lines. The airflow calculation determines the fan specification, duct sizing, and the canopy face velocity.

1. Calculate the volume of the space in cubic metres.
2. Multiply by the required air changes per hour - 20-30 for commercial kitchens under DW/172, and 6-10 for general offices and commercial spaces under Approved Document F.
3. This gives the required total airflow in m³/h. A 40 m³ kitchen at 25 air changes per hour requires 1,000 m³/h of extract capacity.
4. For kitchen projects, check the canopy hood sizing. The face velocity across the canopy open area should typically be 0.25-0.35 m/s for standard cooking loads under DW/172.
5. Size the supply air volume to match the extract volume, minus a small negative pressure margin to keep the kitchen slightly negative relative to front-of-house. This prevents cooking odours from spreading into the dining area.

Step 4: Build the Quote Accurately

Commercial ventilation quotes have more moving parts than most trade contractor quotes. A typical kitchen system includes: extract canopy (fabricated or proprietary), grease filters, inline or centrifugal extract fan, fire-rated ductwork, fire dampers at compartment penetrations, backdraught dampers, supply air unit or fresh air intake, electrical wiring and controls, commissioning and balancing, and handover documentation.

List every line separately. Bundling materials and labour into a lump sum makes it very difficult to track costs during the project and leaves you exposed if the customer challenges specific items.

Typical installed cost benchmarks from the UK market in 2026:

• Simple takeaway or small cafe extract system: £3,000-£5,000
• Cafe or bistro with make-up air and grease management: £5,000-£12,000
• Full restaurant with balanced supply, grease extraction, and fire suppression integration: £12,000-£30,000
• Large commercial kitchen with automation and monitoring: £30,000-£50,000+

Within those ranges, the main cost drivers are duct run length, structural penetrations, fire-rated construction requirements, and electrical supply works.

Break the quote into sections: supply of plant and materials, ductwork fabrication and installation, electrical connections, commissioning, and compliance documentation. This structure makes your pricing transparent to the customer and makes it easier for you to manage costs against budget as the job progresses.

For projects involving significant plant - AHUs, MVHR units, or large inline fans - send requests for quotation to your suppliers early. Lead times on specified ventilation equipment regularly run 4-8 weeks. Quoting without a supplier price means using allowances that may not hold by the time you place the order.

Step 5: Manage Procurement and Programme the Works

Once the quote is accepted, the first task is locking in your plant order. Equipment is typically the long-lead item on a ventilation job. Ductwork can be fabricated or sourced locally with shorter lead times, but specified fans, AHUs, MVHR units, canopy hoods, and fire suppression interlocks require early commitment.

1. Issue purchase orders to fan and AHU suppliers immediately after contract award. Confirm lead times and delivery dates in writing.
2. Order canopy hoods. Proprietary pressed-steel canopies may be available from stock; custom stainless fabrications to specific widths and projection distances are made to order and typically take 3-5 weeks.
3. Arrange ductwork supply or fabrication. Confirm whether spiral or rectangular duct, gauge, and any fire-rated sections are required, and schedule delivery to match the installation programme.
4. Coordinate with the main contractor or kitchen fit-out contractor to agree the installation sequence. Ductwork and canopy installation usually needs to happen before kitchen equipment is positioned - confirm this programme in writing.
5. Arrange electrical connection sub-contractors if wiring is being let to a specialist. Confirm Part P compliance for all new circuits.

Step 6: Install, Commission, and Document

Installation on commercial ventilation follows a clear sequence: structural penetrations first, then ductwork, then plant, then electrical connections, then commissioning and balancing. Work out of sequence and you will typically need to pull ductwork back out to correct something.

1. Core drill or break out structural penetrations for duct runs through walls and ceilings. Install fire sleeves and fire-rated collars at compartment walls before duct runs are connected.
2. Install the extract canopy in position. Confirm the hanging height above the cooking line per DW/172 - typically 1.8-2.0 metres above floor level for standard cooking equipment.
3. Run ductwork from canopy to fan and from fan to discharge terminal. Minimise bends; each 90-degree bend adds the equivalent resistance of approximately 1.5 metres of straight duct.
4. Install grease filters in the canopy. For kitchens, baffle filters are the compliant standard under DW/172 for high-grease environments. Mesh filters are not acceptable in these applications.
5. Install fire dampers at all compartment wall and floor penetrations. Record the manufacturer, model, and location of each damper on the as-installed drawing.
6. Connect the extract fan, controls, and any interlocks to the fire suppression system if one is present.
7. Commission and balance the system. Measure actual airflow at each extract point using an anemometer and capture readings against the design specification. Adjust dampers to achieve the target flow rates.
8. Record all commissioning data on the commissioning sheet and produce the complete handover pack before invoicing.

Step 7: Issue the Handover Pack and Final Invoice

A commercial ventilation handover pack is not optional - building control, the environmental health officer, and the fire authority may all request it. A complete pack typically includes:

• As-installed drawings showing duct routing, fire damper locations, and the discharge point
• Commissioning and balancing certificate showing measured airflow rates against design specification
• Fan and AHU manufacturer data sheets and installation manuals
• Fire damper test certificates and intumescent product data sheets
• Grease filter cleaning and maintenance schedule
• TR19 baseline duct cleanliness certificate for large or complex kitchen systems
• Electrical installation certificate for all new circuits

Invoice at the agreed stage milestones. Most ventilation contractors invoice on deposit at contract award (25-30%), materials delivery, practical completion of installation, and commissioning sign-off. Tying invoices to milestones makes payment predictable and keeps cash flow positive throughout the project. Do not issue the commissioning-stage invoice until the commissioning documentation is signed off by the customer - this protects you against disputes over whether the job is actually complete.

Keeping the Job Profitable

Margin on ventilation projects leaks in predictable places: under-estimated ductwork quantities, plant lead times that push programme and increase preliminary costs, unexpected structural penetrations that were not scoped at survey, and commissioning that takes longer than allowed because the system does not balance first time.

Build contingency into complex ductwork runs. Always price structural penetrations as a provisional sum until you have confirmed the construction type. Allocate half a day to commissioning and balancing for a small kitchen system; a full day for larger installations. If the system fails to balance on commissioning, the cause is almost always a discrepancy between the design airflow and the actual installed resistance - check duct lengths and bend counts against the survey plan before assuming the fan specification is wrong.

For businesses running multiple ventilation jobs simultaneously, tracking live procurement status, commissioning milestones, and stage invoicing in a single job record removes the risk of invoices being delayed because commissioning documentation was saved on someone's laptop rather than attached to the job. Zigaflow connects quote, job, purchase orders, and invoices in one place, so the commissioning sign-off that triggers the final invoice is visible to the whole team, not just the engineer who was on site.

• Commercial Ventilation Systems UK: Complete Guide 2025Inergy Group · accessed 2026-07-10
• Cost of Installing Extractor Fan in a Kitchen 2026eFans Direct Ltd · accessed 2026-07-10
• DW 172 Specification for Kitchen Ventilation SystemsBuilding Engineering Services Association (BESA) · accessed 2026-07-10
• Ventilation Brands Used in UK Commercial Kitchens (2026 Guide)Fan Services Ltd · accessed 2026-07-10

See it in Zigaflow