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Condensation, mould and landlords

Indoor air quality surveys for homes, schools and workplaces

CO2, humidity and particulates logged for a week, with plain-English findings.

  • From £145 inc VAT per home
  • Charged visit, price agreed first
  • Airflow tested and recorded
Get a guide price0800 088 6341
Air quality monitor on a table in a classroom

An indoor air quality survey measures how fresh and how damp the air in a building really is, over days rather than minutes. We place loggers that record CO2, humidity and temperature (and particulates in workplaces), then explain what the readings mean and what ventilation changes would help.

How it works

CO2 is a practical indicator of whether a room is getting enough fresh air for the number of people in it: levels that climb steadily through a meeting or a night in a bedroom point to under-ventilation. Humidity readings show whether moisture is being removed or lingering long enough to cause condensation and mould.

Surveys are useful before spending money: they show whether a problem is constant or happens at particular times, which rooms are worst, and whether an existing system is doing its job.

Options we fit

Home survey

Loggers in bedrooms, living areas and wet rooms for 7 days, with a written summary.

Workplace survey

CO2, humidity, temperature and particulates in offices, classrooms or meeting rooms.

Before and after

Readings taken before and after a ventilation upgrade to show the difference.

Spot checks

Readings taken during a single visit, where a quick answer is enough.

Signs you need this

  • Headaches or drowsiness in meeting rooms or classrooms
  • Condensation and mould with no obvious cause
  • You want evidence before spending money on ventilation
  • Staff complaints about stuffiness
  • A new ventilation system that does not feel right
  • A bedroom that feels stale in the morning

Guide prices

Indoor air quality surveys guide prices
WorkGuide price
Home air quality check: CO2, humidity and temperature logged for 7 days (per home)£145–£245 inc VAT
Workplace air quality survey: CO2, PM2.5, humidity, 7 days logged, written report (per survey)£495–£1,195 + VAT

Guide prices using West Midlands (our baseline) rates. Home prices include VAT at 20%; business prices exclude VAT. A guide price is not a quote: we confirm a fixed price in writing first. London is about 20% higher and the North East about 8% lower.

What happens, step by step

  1. Plan

    Agree rooms and logging period.

  2. Place loggers

    Devices placed away from windows and heat sources.

  3. Log

    Readings taken every few minutes for around 7 days.

  4. Analyse

    Patterns compared with occupancy and ventilation.

  5. Report

    Plain-English findings and recommended next steps.

The rules that apply

England

In England, ventilation is covered by Part F of the Building Regulations and its guidance, Approved Document F (2021 edition). Workplaces must also be ventilated with a sufficient quantity of fresh or purified air under the Workplace (Health, Safety and Welfare) Regulations 1992.

Wales

Wales has its own Part F ventilation guidance, published by the Welsh Government, and work is checked by building control. The Workplace (Health, Safety and Welfare) Regulations 1992 also apply, requiring sufficient fresh or purified air.

Scotland

In Scotland, ventilation is covered by the Building (Scotland) Regulations and section 3 of the Technical Handbooks, and most building work needs a building warrant first. The Workplace (Health, Safety and Welfare) Regulations 1992 apply in Scotland too, requiring sufficient fresh or purified air.

Northern Ireland

In Northern Ireland, ventilation is covered by the Building Regulations (Northern Ireland) and Technical Booklet K. Northern Ireland has its own Workplace (Health, Safety and Welfare) Regulations (Northern Ireland) 1993 with the same duty to ventilate.

Questions people ask

What is a good CO2 level indoors?

Outdoor air is around 400 to 450 parts per million; indoor levels that stay well below about 1,000 ppm usually indicate reasonable ventilation for the people in the room, while sustained levels much higher suggest it needs improving.

What humidity should a home be?

Relative humidity of roughly 40 to 60 percent is comfortable for most homes. Readings that sit above 70 percent for long periods make condensation and mould much more likely.

How much does an air quality survey cost?

A home survey costs £145 to £245 including VAT, and a workplace survey £495 to £1,195 excluding VAT, depending on the number of rooms.

How long do the loggers stay?

Usually around 7 days, so the readings cover normal weekday and weekend use.

Will you sell me a system after the survey?

Only if the readings show you need one. The report sets out the cheapest effective options.

Do you measure particulates?

Workplace surveys include PM2.5 particulates; homes can have them added on request.

Related services

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