Extract Ventilation Testing
Ventilation airflow testing for new-build homes and residential conversions, helping confirm that extract systems have been installed, configured and commissioned correctly.
Ventilation Testing for New Dwellings
New-build residential developments and conversion projects that create new dwellings commonly require ventilation testing before completion. The purpose of the test is to confirm that the installed system delivers the intended airflow and has been configured correctly.
Ventilation systems can range from simple background ventilators and intermittent extract fans through to whole-house mechanical extract and heat-recovery systems. The testing method depends on the system installed and the rooms served.
One Stop Consult coordinates extract ventilation testing through experienced technicians using suitable calibrated equipment. The results can support project completion and the information required by the relevant Building Control body.
Why Is Extract Ventilation Testing Required?
Testing confirms that the installed ventilation system performs as intended rather than relying solely on product specifications.
Airflow Validation
The measured extract rate confirms whether the fan or whole-house system is moving the required amount of air.
Correct Configuration
Testing can identify systems that have been left on the wrong setting or have not been balanced correctly.
Moisture Control
Adequate extraction helps remove moisture generated in kitchens, bathrooms and utility rooms.
Project Completion
Ventilation test information may be required as part of the completion package for Building Control.
Systems That May Require Testing
The existing OSC service covers five common ventilation system types, ranging from intermittent fans to whole-house mechanical systems.
Background Ventilation
Trickle ventilators and other background openings provide continuous low-level ventilation alongside extract provision.
Intermittent Extract Fans
Individual fans operate when required in wet rooms such as kitchens, bathrooms and utility rooms.
Continuous Mechanical Extract
A whole-house system extracts continuously from wet rooms and may operate at different normal and boost rates.
Mechanical Ventilation With Heat Recovery
MVHR systems extract stale air and supply fresh air while recovering heat through a central unit.
Centralised Systems
Multi-room or multi-unit arrangements may require balancing and commissioning across several terminals.
Mixed Ventilation Strategies
Some projects use a combination of background, intermittent and continuous ventilation measures.
Typical Extract Rates Referenced on the Existing OSC Page
The original One Stop Consult service page lists the following airflow benchmarks for common wet-room extract arrangements. The applicable requirement should always be confirmed against the project specification and the relevant version of Approved Document F.
The overall dwelling ventilation requirement also depends on the size and number of bedrooms within the property.
Whole-Dwelling Ventilation Rates
In addition to room-by-room extract rates, the dwelling must achieve an adequate overall ventilation rate. The original OSC page notes that this increases with the number of bedrooms.
As examples from the existing service information, a one-bedroom property is referenced at 13 litres per second, while a five-bedroom property is referenced at 29 litres per second. The correct target for each scheme should be confirmed from the design and current compliance documentation.
How Extract Ventilation Testing Works
The technician measures airflow at the relevant terminals and checks the system settings against the required design performance.
System Review
Confirm the ventilation type, fan locations and required design rates.
Operational Check
Check that fans and controls are functioning and accessible.
Airflow Measurement
Measure extract performance at each required terminal.
Balancing or Adjustment
Where applicable, adjust system settings to improve performance and balance.
Final Documentation
Record the measured results for the project completion package.
Preparing for the Ventilation Test
The system should be fully installed, powered and operational before the technician attends. Incomplete grilles, ductwork, controls or electrical connections can prevent meaningful testing.
Good access to all relevant rooms and terminals will help the appointment proceed efficiently.
Why Ventilation Systems Fail Testing
Low airflow is often caused by installation, commissioning or ductwork issues rather than the fan unit alone.
Incorrect Fan Setting
The unit may have been left on a low commissioning setting or may not be entering boost mode correctly.
Restricted Ductwork
Long, crushed, undersized or excessively flexible duct runs can significantly reduce airflow.
Too Many Bends
Sharp bends and poor routing increase resistance and reduce the volume of air delivered.
Unbalanced Terminals
One outlet may receive too much airflow while other rooms remain below their required rate.
Blocked or Closed Valves
Terminals, grilles, dampers or filters may be restricted, incorrectly adjusted or obstructed.
Missing Background Ventilation
Extract performance and overall ventilation can be affected where the intended air inlets have not been installed or opened.
What Happens If the System Does Not Achieve the Required Airflow?
The cause should be investigated before the system is retested. Straightforward issues may include incorrect settings, closed valves or incomplete controls. More significant failures may require changes to the ductwork, fan specification or system layout.
Early commissioning is beneficial because access to ductwork and controls may become difficult once final finishes and boxing are complete.
Extract Ventilation Testing for Residential Projects
Information Required for a Quotation
Provide the full project address, number and type of dwellings, installed ventilation system and preferred test date.
For larger developments, please also provide floor plans, the ventilation design or commissioning schedule, system manufacturer and confirmation of which plots require testing.
Nationwide Extract Ventilation Testing Service
One Stop Consult coordinates ventilation airflow testing for residential projects throughout mainland UK. Support is available for individual dwellings, conversion schemes, apartment developments and larger multi-plot sites.
Other Services Your Project May Require
Important Ventilation Testing Information
The applicable airflow requirements depend on the project, ventilation system, design specification and relevant version of Approved Document F. The system must be fully installed, powered and accessible on the agreed test date. Incomplete ductwork, controls, grilles or electrical connections may prevent testing or affect the result. Additional charges may apply for aborted visits, adjustment work or retesting. One Stop Consult provides consultancy and coordination support through its specialist testing network.
Extract Ventilation Testing FAQs
Which projects require ventilation testing?
New residential buildings and conversion projects forming new dwellings commonly require airflow testing and commissioning.
What does the test measure?
It measures the airflow delivered or extracted at relevant ventilation terminals and compares this with the required design performance.
What equipment is used?
The technician uses suitable calibrated airflow-measurement equipment appropriate to the installed terminal and system.
Do intermittent fans need testing?
Intermittent kitchen, bathroom and utility-room extract fans can require airflow validation as part of the completion process.
Can you test MVHR and whole-house systems?
Yes. Whole-house mechanical extract and heat-recovery systems can require commissioning, balancing and recorded airflow results.
Why might a fan fail the airflow test?
Common causes include incorrect settings, restrictive ductwork, sharp bends, blocked terminals, poor balancing or an undersized system.
When should testing be completed?
Testing should take place once the system is complete and operational, with enough time remaining for adjustments or remedial work before handover.
What information is needed for a quote?
Provide the project address, number of dwellings, system type, plans or ventilation design where available, and preferred date.
Do you provide ventilation testing nationwide?
Yes. We coordinate suitable technicians for eligible projects throughout mainland UK.
Request Your Free Extract Ventilation Testing Quote
Complete the form below with the project address, number of dwellings, ventilation system type and preferred test date. Upload the latest plans, ventilation design or fan schedule so our team can review the requirement and coordinate an appropriate quotation.