Ductwork near you

Before quoting for duct routes it is worth being clear about which of these you have, because the trade, the materials and the sign-off differ. Many homeowners who ask for ductwork turn out to need a single extract route done properly.

The single most common reason a fan underperforms in a British house is the duct it was given. Approved Document F is direct about this: rigid ducts should be used wherever possible. Where flexible ductwork is installed, lengths should be a maximum of 1.5 metres, it should meet the standards of BSRIA's BG 43/2013, and it should be installed so that the full internal diameter is maintained and flow resistance is minimised, which means pulling the duct taut rather than leaving it concertinaed.

That guidance exists because the alternative is so common. A three-metre coil of ribbed hose looped over a loft joist, half collapsed and sagging where condensate has pooled, can strangle a fan that would have met its rate through a short rigid run. Noise is governed by the same detail: Approved Document F expects systems to be designed and installed to minimise noise, including correctly sizing and jointing ducts and fixing equipment securely, for instance on resilient mountings.

A duct route is designed backwards from where the air has to leave the building, then checked against the obstacles in between: joist directions, the line of a steel, a cavity tray, a fire compartment, and whatever the outside wall looks like from the street. The shortest sensible run with the fewest bends is almost always the right answer, and it is far cheaper to argue about it on paper than after the ceiling is closed.

Approved Document F sets out where things sit. Extract terminals and fans, not including cooker extract hoods, should be installed as high as is practicable in the room and a maximum of 400 millimetres below the ceiling. Where a cooker hood extracts to the outside, the height of the hood above the hob surface should be as specified in the manufacturer's instructions or, where there is no specification, between 650 and 750 millimetres. Internal doors matter too: air has to be able to move through the dwelling, with a minimum free area equivalent to a 10 millimetre undercut in a 760 millimetre wide door.

The job is not finished when the grille goes on. Approved Document F expects air flow rates to be measured and recorded in litres per second, so ask for those figures rather than an assurance that the fan is running. A number on a commissioning sheet is the only evidence that the duct you paid for is delivering what the room needs.

Ventilation equipment is treated as a controlled service or fitting, and providing or extending it in or in connection with a building is building work, so duct routes are not outside the Building Regulations. GOV.UK explains that you do not need to apply for approval yourself if you use someone registered with a competent person scheme, which is the usual route for this kind of work. There is a narrow relief worth knowing: Approved Document F notes that replacing an extractor fan or a cooker hood using the existing cabling does not need to be notified to a building control body.

Fire separation is the requirement people forget. Approved Document F points out that the requirements of Part B apply where ducts pass through a fire resisting structure or a fire compartment, which covers routes that cross a protected stairway, a garage wall or the separating wall of a flat. Getting that detail wrong turns a ventilation improvement into a fire safety defect.

In older properties, assume nothing about what you are cutting into. HSE states that asbestos may be part of any commercial or domestic building built or refurbished before the year 2000, and that if you disturb something you suspect contains asbestos you should stop work immediately, confirm what it is or assume it is asbestos, and carry out a risk assessment, under the Control of Asbestos Regulations 2012. Textured decorative coatings and insulating board sit exactly where duct routes tend to go.

Scotland and Northern Ireland run separate systems. In Scotland the Building (Scotland) Act 2003 works through a building warrant granted before work starts and a completion certificate before a building is occupied, with the technical handbooks giving the guidance, ventilation in Section 3 and energy in Section 6. In Northern Ireland the Building Regulations (Northern Ireland) 2012 place ventilation in Part K and conservation of fuel and power in Part F, so the letters themselves do not match England's.

Approved Document F asks for reasonable access for maintaining ventilation systems, specifically access to replace filters, fans and coils, access points for cleaning ductwork, and access for general maintenance of the plant. On a new MVHR installation that is a design decision made early: a unit buried in a loft behind a water tank, reachable only by crawling over joists, will not be serviced, whatever the intention on the day.

Ask the installer where the access points are and have them marked on the commissioning paperwork. The regulations also require that the person carrying out the work gives the owner sufficient information about the building's ventilation system and its maintenance requirements, so that the system can be operated to provide adequate ventilation. That handover pack is what a future plumber, cleaner or buyer's surveyor will work from.

Duct quotes are hard to compare because contractors solve the route differently: one prices a short rigid run through the gable with a new terminal, another prices a longer path to keep the external wall untouched. Ask each to state the duct material, the length and diameter, the number of bends, where the terminal goes and the air flow rate they will commission to, and the comparison becomes possible.

On LokalMatch you describe the job once, with the room, the building type and photographs of the likely route, and matched local pros get in touch with you. Pros pay for the requests they receive, which is how the site is funded. LokalMatch does not carry out the work and does not set prices, and it does not vet, rank or recommend anyone, so checking competence, insurance and scheme membership remains yours to do.