Ventilation for new builds, extensions and lofts in Cornwall

New homes, extensions and loft conversions need ventilation that meets the building regulations and is tested before sign-off. We design the system, install it at the right stage of the build, measure the airflows and provide the commissioning information building control asks for.

Cornwall has every kind of building, from old terraces to new estates and business parks, and every job is designed around the building in front of us, not a standard kit.

New builds & extensions in Cornwall at a glance

Area: Cornwall
Towns listed: 10, largest Redruth
Postcode districts: PL11, TR12, TR13, TR14, TR15 and TR3
Price region: South West
Survey: Free survey (UK mainland)

What the work involves

For new dwellings in England, Approved Document F sets whole-home ventilation rates and requires mechanical systems to be commissioned and the results given to building control. Extensions and loft conversions have their own triggers: a new wet room needs extract, a new habitable room needs background ventilation or a connection to the ducted system, and energy-efficiency work can mean the existing home needs more ventilation too. We work for self-builders, small developers, builders and architects.

Commissioning only

Testing and paperwork for systems installed by others.

MVHR for new builds

Design, first fix, second fix and commissioning for whole-home heat recovery.

MEV or dMEV

Continuous extract systems where MVHR is not specified.

Guide prices in Cornwall

Ventilation for new builds, extensions and lofts guide prices in Cornwall
Work	Guide price
MVHR in a new build or full renovation (fitted at first fix), 3 to 4 bedrooms (per home)	£5,150–£8,250 inc VAT
Continuous-running extract fan (dMEV) with humidity boost, flow tested (per fan)	£360–£625 inc VAT
Airflow testing and commissioning sheet for extract fans (up to 6 fans) (per home)	£150–£305 inc VAT
MVHR or MEV commissioning test, every terminal measured and recorded (per system)	£255–£410 inc VAT

These ranges use our South West rates. Prices include VAT at 20%. You get a fixed written price before any work is booked.

Common reasons people call

You are adding a bathroom or kitchen in an extension or loft
You are insulating and re-windowing an existing home
A self-build with an airtightness target

Rules in England

English building work follows Approved Document F (2021 edition) for ventilation rates, installation and commissioning. For homes, it sets minimum extract rates such as 15 litres a second for a bathroom and 30 or 60 for a kitchen, and expects mechanical systems to be airflow-tested.

How the job runs

Drawings
Design
First fix
Second fix
Commission

Towns we cover in Cornwall

Questions about ventilation for new builds, extensions and lofts in Cornwall

Is the survey free in Cornwall?

For new installations on the UK mainland, yes. The survey is free and the quote that follows is fixed and in writing. Servicing, testing and repair visits are charged, and we confirm the cost before booking.

When should MVHR be fitted in a new build?

MVHR ducts should go in at first fix, after the structure and before plasterboard. Planning it at design stage avoids clashes with joists and steels.

Who signs off the ventilation commissioning?

The installer measures the airflows and completes a commissioning sheet, which goes to building control; for new dwellings in England that is expected within five days of completion of the commissioning.

Which rules apply to ventilation in Cornwall?

In England, ventilation in new and altered homes is covered by Approved Document F of the Building Regulations. Landlords also have duties under the Housing Health and Safety Rating System, and workplaces must be ventilated under the Workplace (Health, Safety and Welfare) Regulations 1992.

Which towns in Cornwall do you cover?

All of Cornwall, including Falmouth, St Austell, Truro, Camborne and Newquay. If your town is not listed, send the postcode and we will confirm.