Building Regulations Approved Document F

Approved Document F of the Building Regulations deals with the ventilation in and around a property. If you have browsed through Approved Document L then you will be aware that this document is in place to ensure that buildings are as energy efficient as possible that includes essentially insulating and sealing a building against draughts.

Document F may seem like a bit of a contradiction to Document L – first you seal a building up and then you are told that you must ventilate it! In actuality both documents are concerned with controlling ventilation – Document L aims to resolve any uncontrolled ventilation that can decrease efficiency and Document F to ensure there is air circulation in a building etc….

As with other Approved Documents there are set rules for both dwelling and non-dwelling buildings due to the nature of their use.

F1 – Ventilation within a Building

The requirements of point F1 of Document F state that there should be adequate and suitable ventilation provided for a property and the people within it and point F2 states that where mechanical ventilation is used it should be first commissioned through a testing process where it is adjusted via controls to ensure that point F1 is met.

Where mechanical ventilation is present and testing is required the following points should be adhered to:

• Whoever installs a mechanical ventilation system should provide the owner with full operating and maintenance instructions so the system can run at the required levels
• Where applicable, a new system needs to be fully tested in line with the guidelines stated by the Secretary of State
• All test results should then be submitted to the relevant local authority
• All data and results from testing should be stored in the manner stated by the Secretary of State
• Test results should be supplied to the local authority not more than five days after the final test is completed. Where the regulations do not apply, the local authority should be notified no more than 30 days after works are completed

It should be noted that these regulations do apply where paragraph F1(2) states but they do not apply to the extension of any fixed ventilation system or manner of control where adjustment to the system as a whole cannot be made.

In terms of Approved Document L, where paragraph L1(b) is relevant, the regulations apply to any and all building works but these rules do not apply where any fixed services are to be extended and testing or adjustments cannot be made or where improvements to energy efficiency of the service cannot be improved.

Ventilation within Dwellings

Where the regulations stated above apply to a dwelling, in most cases there are three different types that are needed:

• Whole of building ventilation
• Extract ventilation
• Purge ventilation

Whole of Building Ventilation

This type of system ensures that air within a building space in continually changed. This type of system itself can also be reduced (turned down) and even turned off if the building is not in use (e.g. an air conditioning system).

Extract Ventilation

This type of system is normally put into use in areas of high humidity or pollution and is used to draw the whatever is required from the air space within a room. An example of this type of system would be an extractor fan within a bathroom used to reduce the amount of moisture in the air and help to reduce condensation.

Purge Ventilation

The third type of system is the purge system. This is also used to remove items from the air within a room or building. With this system type there does not necessarily need to be a complicated series of fans and vents, it is as simple as opening a window or a door!

Depending on the nature of the room and what will need to be extracted from the air will depend largely on what type of system will need to be installed.

Ventilation in Non-Dwelling Buildings

When it comes to non-dwelling buildings another element comes in to play – cooling! For further information on this you will need to refer to Approved Document L2a

In pretty much all cases, regardless of the usage of the building, you will need to pay attention to the following:

• Air that is continuously circulated via air conditioning or other mechanical ventilation systems
• The potential for Legionnaire’s disease
• Ensuring that the system can be easily repaired and maintained

Offices and Places of Work

The regulations that cover offices and places of work also cover areas such as leisure centres, commercial kitchen etc…. Rooms that are found within office buildings and complexes such as store cupboards, changing and wash-rooms and toilets etc…. also fall under these defined regulations.

In essence, due to the presence of people within them, these types of structures require similar levels of ventilation largely for the same reasons. However, in this case there are several methods of achieving ventilation levels that provide the required air flow rate:

• Through the provision of natural ventilation
• Through following the guidelines stated in CIBSE Manual AM13:2000 Guide A and B2
• Through using a ventilation system that can be proved to meet required air quality and moisture levels

Properties and Buildings that Already Exist

Where alterations are to take place to an already existing building it should be ensured that the existing part of the building retains its current performance and that these current performance levels are not decreased by the introduction of any new building or improvement works.

When it comes to domestic buildings, one of the most common improvements that can affect the overall ventilation within a building is the replacement of existing windows or introduction of a new window(s). It should be ensured that any new windows comply with rules set out in Approved Documents L and N.

The above is a brief rundown of what is covered and stated in Approved Document F and as with all other Approved Documents you should ensure that you are referencing the most current and up-to-date regulations before commencing and building work. To these ends please refer to the official Approved Document that can downloaded from the Planning Portal website on the link at the top of this page.

Approved Document F Updates – 15th June 2022

As and when required the building regulations documents are updated to reflect new innovations or requirements for structures to meet and on the 15th of June 2022 new upadtes to Approved Document F are due to come into effect.

The changes are being brought in to bring the current Document L up to date with new net zero requirements to help meet the 2025 Futures Homes Standard. A summary of these changes are as follows:

• Main aim is to simplify ventilation requirements
• Align air tight testing and overall system performance
• The specifications of the changes and how they need to be implemented may differ between buildings/area, depending on how they are used
• Focus on air quality and ensuring it’s as clean as possible with no pollutants that could affect inhabitants
• Where the risk of airborne infection is great in office buildings and the similar non-domestic buildings, co2 monitors are to be used
• Where mechanical ventilation is used in common areas, offices and the similar non-domestic buildings, minimum air supply rate should be 0.5 l/s.m2, below the governments proposed rate
• Where recirculating air ventilation systems are used in non-domestic buildings, they should feature the ability to filter or clean the air that’s recirculated, if not then it shouldn’t be used
• If any energy efficiency work is carried out to domestic properties, the ventilation should not be made any worse
• Where windows are replaced in domestic properties they should be fitted with trickle vents unless it can be proved that existing ventilation levels are not affected
• Where mechanical ventilation or background ventilation systems are fitted it should include guidance for the homeowner on why ventilation is important
• When ventilation systems are installed in homes it should include a commissioning sheet and system design documentation for the homeowner
• An official checklist should be provided to builders and those working on an existing property to help understand the impact of any past or future works and how this will affect ventilation