Damp

What does ventilation mean in a home survey?

Approved Document F is the England requirement for ventilation when building work is done. A survey can see the sort of things that document is about: trickle vents, extract fans, and background ventilation that is missing or painted shut. A home survey is not an air test. It does not measure an air-change rate.

Last reviewed 24 October 2026. Written for buyers in England and Wales unless a source says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.

What is Approved Document F?

Approved Document F is the building-regulation guidance for ventilation in England. It applies when building work is being done, for example a new dwelling, a conversion, or replacement windows that change how the room is ventilated. It is not a retrospective test that every older house is expected to pass unchanged. Wales publishes its own approved documents. Do not quote the England document as if it were the Welsh one.

The document is about enough ventilation for the building, including background ventilators and extract from kitchens, bathrooms and similar rooms. Trickle vents in window frames are one common way of providing background ventilation. They are not the only way, and this page does not turn the document into a parts list for your house. It also does not repeat airflow numbers. Those figures live in the document for designers. Copying one into a survey negotiation invents a precision the visit did not measure.

What can a surveyor actually see?

A Home Survey is visual. The surveyor can see a trickle vent that has been painted shut, a hole in the wall where a fan used to be, an extract fan with a grille clogged shut, air bricks buried by a new path, or a kitchen with no obvious extract to outside. They can see condensation on glass and mould on a cold corner, and they can say those two often travel together. They cannot see ductwork buried in a ceiling if there is no access, and they do not measure whether a fan moves the air it was designed to move.

Trickle vents: present, missing, closed, or painted shut.
Extract fans: present in the kitchen and bathroom, or not, and whether the grille is blocked.
Air bricks and background vents: clear, or covered by soil, render or furniture.
Signs that moisture is lingering: streaming windows, mould on cold surfaces, a tumble dryer with nowhere to send the air.
What they could not see: ducts, roof-void fans, and anything behind fitted units.

How does poor ventilation show up as damp or mould?

Moisture from cooking, bathing and drying clothes has to leave the building. If it cannot, it condenses on the coldest surfaces and mould can follow. GOV.UK’s damp and mould guidance, written for rented-housing providers, treats that pattern as a health risk and tells providers to look at causes such as inadequate ventilation, not only at the stain. The guidance is not the RICS rating system. A surveyor may still give a condition rating to the defect they see. The number follows the RICS definitions. It is not an air-quality certificate.

Do not jump from “no trickle vents” to “rising damp”. Condensation, leaks and ground moisture are different, which is what the damp and condensation pages are for. New windows without a vent path are a common part of the condensation storey. So is a bathroom door that is kept shut with the fan off. The survey can note the physical clues. The people who live there produce the moisture, but the building still has to be able to deal with ordinary living. The GOV.UK guidance does not treat damp and mould as something to dismiss.

Why is a home survey not an air test?

An air test measures how the building performs. A Home Survey does not. The surveyor does not report an air-change rate, and this guide will not invent one. If you need a measured result, that is a different appointment, with equipment, after you have decided the question is worth it. For most buyers the useful step is simpler: read which vents are missing or shut, get those working, and deal with any leak the survey actually found.

Approved Document F remains the England reference when someone is doing building work that must provide ventilation. A survey sentence is not building-control approval. If replacement windows were installed without vents, your solicitor can ask about building regulations. The surveyor’s job is the condition they could see, including whether the house is set up to be ventilated at all. Heating and the boiler are a related comfort question, not a substitute for a vent. They are covered on the plumbing and heating page, and gas safety is a separate regime.

Common questions

Does an older house have to pass Approved Document F before you buy it?

No. Approved Document F is the England guidance for ventilation when building work is carried out. It is not a pass certificate that every existing house must already meet. A survey can still say the home is under-ventilated from what the surveyor could see: painted-shut vents, no extract, mould on cold walls. Wales has its own building regulations.

Are trickle vents the only acceptable ventilation?

No. They are a common form of background ventilator, and a survey can see if they are missing or painted shut. Approved Document F is about adequate ventilation for the work in question, not about one product. This page does not specify a vent size.

The bathroom has no extract fan. Is that a survey defect?

It is something the surveyor can record, especially if there is mould or streaming condensation. Whether past building work failed a regulation is a separate question. The useful point is that moisture from bathing needs a way out. A fan that is painted shut or dead is not doing that.

Will the survey measure the air-change rate?

No. A Home Survey is not an air test. This guide does not state a rate in air changes or in litres per second. If a measured test is what you need, commission that test. Do not stretch a visual note until it pretends to be one.

Is poor ventilation the same as mould?

Often they travel together, because condensation on cold surfaces feeds mould. They are not identical. A leak can cause mould in a well-ventilated room. Read the mould page and the damp page. GOV.UK’s rented-housing guidance treats damp and mould as a health risk and points at causes including ventilation.

The vents are painted shut. Does that matter?

Yes, if they were the background ventilation. Paint across a trickle vent or an air brick stops the air path the fitting was there to provide. The survey can see that. Opening or replacing the vent is ordinary maintenance once you own the house. It is not an air test.

Do new windows have to have trickle vents?

In England, replacement windows that are building work are judged against the ventilation guidance in Approved Document F, which expects the ventilation of the room to be maintained. A trickle vent is a common way to do that, not a slogan. Ask what was done on this house. The survey sees the frames. Building control sees the compliance route.

Does Approved Document F apply in Wales?

The document cited here is the England guidance. Wales has its own building regulations and approved documents. The physical point is the same: a survey can see blocked vents and missing fans, and it still is not an air test. Do not cite the England document as the Welsh rule.

Sources

Key facts

Approved Document F: Statutory guidance for England on ventilation when building work is carried out. Wales has its own building regulations. Document F is not a result for an unaltered older house.
What a survey can see: Trickle vents, air bricks, extract fans in kitchens and bathrooms, and vents that are missing, blocked or painted shut.
What it cannot do: A Home Survey is not an air test. This guide does not state an air-change rate or a fan flow in litres per second.
Damp and mould: GOV.UK’s guidance for rented-housing providers links inadequate ventilation with damp and mould as a health risk. That guidance is not a RICS rating.
Heating and moisture: Ventilation sits alongside how the home is heated and how much moisture is produced. The survey does not run a heating design or a boiler service.