Childwall, Merseyside
Positive input ventilation (PIV) in Childwall
Loft or wall units that gently push filtered air into the home to tackle condensation. Covering Childwall and L15, L16 and L18.
- From £750 inc VAT per home
- Free survey

For a typical Childwall semi or terrace, a loft PIV unit is often the quickest way to dry the house out.
Work in Childwall follows the rules for England and finishes with a written record of what was fitted and how it was set up.
PIV in Childwall at a glance
- Town
- Childwall, Merseyside
- Postcode districts
- L15, L16 and L18
- Nearby
- Wavertree (1 mile), Old Swan (1 mile) and Knotty Ash (1 mile)
- Price region
- North West
- Survey
- Free survey (UK mainland)
What the work involves
Loft air is usually a little warmer and drier than outside air, and the unit filters it before it comes down into the house. Many units have a temperature sensor that reduces the flow or switches to a heater module on cold days, so the incoming air does not feel like a draught.
Loft-mounted PIV
The most common option for houses with a loft. Usually fitted in half a day.
Heated PIV
A heater module tempers the incoming air in cold weather. Useful in homes where people feel draughts.
Guide prices in Childwall
| Work | Guide price |
|---|---|
| Positive input ventilation (PIV) loft unit, supplied and fitted (per home) | £750–£1,325 inc VAT |
| Wall-mounted PIV unit for a flat (core drilled through an outside wall) (per flat) | £950–£1,600 inc VAT |
| Heater module or heated PIV unit (extra over a standard unit) (extra) | £140–£280 inc VAT |
These ranges use our North West rates. Prices include VAT at 20%. You get a fixed written price before any work is booked.
When to get it looked at
- Black mould on window reveals and in corners of bedrooms
- Musty smell in wardrobes or behind furniture
- The house feels stuffy and damp rather than cold
Rules that apply 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.
Questions from Childwall
What is the price of a PIV unit in Childwall?
Guide prices for Childwall use North West rates: positive input ventilation (PIV) loft unit, supplied and fitted is typically £750 to £1,325 inc VAT per home. We confirm a fixed price in writing before any work starts.
How long does PIV installation take?
A loft unit is normally fitted in two to four hours, including the diffuser and electrical connection.
How much does PIV cost to install?
A loft-mounted PIV unit usually costs £795 to £1,395 including VAT supplied and fitted, and £995 to £1,695 for a wall-mounted unit in a flat. A heater module adds around £145 to £295.
Is the survey free in Childwall?
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.
How do I get a price for a PIV unit in Childwall?
Use the guide price tool, the form on this page, live chat, WhatsApp or call 0800 088 6341. A postcode and a couple of photos help us give you a useful answer first time.
Send a photo of your loft hatch area and landing ceiling for a quicker Childwall quote.
PIV near Childwall
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