Approved Document F - Do I Need To Fit Trickle Vents?

The changes, require the majority of replacement windows and doors to be fitted with trickle vents.


We would recommend you read the Approved Document in full to make sure that you understand all of the changes and requirements. Approved Document F: Volume 1 applies to dwellings


Changes will proceed as planned and come into effect on the 15th June 2022.


The following questions should be considered: Does The Property Already Have Trickle Vents?

  • Yes – The replacement windows and doors must also have trickle vents (or another method of background ventilation), and the size of these vents must not be smaller than those installed in the previous windows.

  • No – go to the next question



Are You Replacing Less Than Or Equal To 30% Of The Windows & Doors In The Property?

  • Yes – No trickle vents are required provided that no more than one other minor energy efficiency measure has been completed at the property such as cavity wall insulation.

  • No – Go to the next question

Please note that windows installed post June 2002 are an energy efficient measure in the same way as cavity wall, draft proofing, loft insulation top up or external wall insulation.

Is There A Mechanical Ventilation With Heat Recovery System Installed At The Building Or Any Other Ventilation Provisions That Can Be Demonstrated To A Building Control Body That They Comply With The Requirements Of Paragraph 3.2?

  • Yes - No trickle vents required

  • No – Go to next question

Paragraph 3.2 reads as follows; When other building work is carried out that will affect the ventilation of the existing dwelling, for example: a. replacing a window or door b. doing energy efficient work the ventilation of the dwelling should either: a. meet the standards in the relevant approved document b. not be less satisfactory than before the work was carried out NOTE: Ventilation through infiltration should be considered to be part of the ventilation provision of a dwelling. Reducing infiltration might reduce the indoor air quality of the dwelling below the standards given in Appendix B.

Does The Property Have Continuous Mechanical Extract Ventilation (a ducted system where a single fan draws air continuously from each room constantly or individual room extract fans)?

  • Yes – No trickle vents required in wet rooms (kitchen, utility, bathroom, WC), but you must fit 4000mm² Equivalent Area in all other rooms.

  • No – Go to next question



Are There Any Other Ventilation Provisions That Can Be Proven Will Not Make The Previous Air Infiltration Of The Property Worse?

  • Yes – Record these provisions and save to the work file, they will be required to be assessed at time of inspection of this property.

  • No – Fit trickle vents



Can You Feasibly Adopt The Minimum Equivalent Vent Sizes Set Out In Table 1 In Each Window?

  • Yes – Install the vents as per the table below

  • No – Install vents as close in size to the table below as possible

The Minimum Equivalent Vent Sizes table
The Minimum Equivalent Vent Sizes table

Please note that these changes are for England ONLY. There are no current changes to the Building Regulations in Wales.