Replacement windows and trickle vents

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replacement windows

This guide is intended to help people involved with replacing windows in existing dwellings to understand the 2021 changes to ventilation requirements of the Building Regulations in England. The article provides details on the key changes, along with examples of how compliance can be achieved. 

This is only a general guide, and you should always check with the Local Authority Building Control Team that your design complies with all the relevant requirements of the Building Regulations.

Background information

Means of ventilation are dealt with under Part F of the Building Regulations. Part F(1) requires that there shall be adequate means of ventilation provided for people in buildings.

This is needed as the internal environment within a dwelling can be affected by airborne pollutants and odours, along with suffering from excess moisture and heat from a variety of sources. In light of this, it is important that dwellings have methods to provide controllable ventilation to provide fresh air from outside as shown in diagram 1 below.

Replacement windows and trickle vents

Diagram 1: Purpose of ventilation. Courtesy of Elmhurst Energy.

The following Approved Documents have been published to provide guidance on the requirements of Part F in England:  

  • Approved Document F Volume 1: Dwellings (2021 edition).
  • Approved Document F Volume 2: Buildings other than dwellings (2021 edition).

This article focuses exclusively on Approved Document F Volume 1: Dwellings (2021 edition), as this is the document that covers replacement windows and trickle vents in existing dwellings.

Transitional arrangements 

Approved Document F Volume 1 (2021 edition) took effect from 15 June 2022. However, it does not apply to work subject to a building notice, full plans application or initial notice submitted before 15 June 2022, provided the work starts onsite before 15 June 2023. The transitional arrangements are summarised below:

Application date / Works commence 

 

Before 15 June 2022

 

After 15 June 2022

Before 

15 June 2023
Approved Document F (2010 edition incorporating 2013 amendments) Approved Document F Volume 1 (2021 edition) 
After 

15 June 2023
Approved Document F Volume 1 (2021 edition) Approved Document F Volume 1 (2021 edition)

Table 1: Summary of transitional arrangements

Is replacing windows in existing dwellings controllable under the Building Regulations? 

Since 1 April 2002 Building Regulations have applied to replacement windows. This is because replacement windows are classified as a “controlled fitting” under Regulation 2 of the Building Regulations 2010, and therefore defined as “building work” under Regulation 3 of the Building Regulations 2010.

Do I need to make a Building Regulations application?

Replacement windows are frequently installed by a person who is a member of a suitable ‘Competent Person Scheme’ as detailed in Schedule 3 of the Building Regulations 2010. In this instance, the installer self-certifies that the works comply with the Building Regulations and notifies your Local Authority Building Control Department that the works have been undertaken. 

It is important that the installer provides the homeowner with a ‘Building Regulation Compliance Certificate’ upon completion, for your records. However, if you're employing someone who isn't registered on a suitable ‘Competent Person Scheme’, you'll need to make a Building Regulations application before commencing works. 

What do I need to do if the existing windows have trickle vents?

If the existing windows have trickle vents, the replacement windows should also include trickle vents which should comply with both of the following conditions:

  1. Not be smaller than the trickle vents in the original window, and 
  2. Be controllable either automatically or by the occupant.

What do I need to do if the existing windows do not have trickle vents?

Replacing the windows is likely to increase the airtightness of the dwelling. If ventilation is not provided via a mechanical ventilation with heat recovery system, then increasing the airtightness of the building may reduce beneficial ventilation in the building. 

In these circumstances, it is necessary to ensure that the ventilation provision in the dwelling is no worse than it was before the work was carried out. This may be demonstrated in any of these following ways:

1) Incorporating trickle vents in the replacement windows equivalent to the following:

  • Habitable rooms – minimum 8000mm2 equivalent area
  • Kitchen – minimum 8000mm2 equivalent area
  • Bathroom (with or without a toilet) – minimum 4000mm2 equivalent area

2) If the dwelling has continuous mechanical extract ventilation, installing trickle vents in any replacement windows which are not in wet rooms, with a minimum equivalent area of 4000mm2 in each habitable room.

3) Specify other suitable ventilation provisions if it can be demonstrated to your Local Authority Building Control Surveyor that they meet the standards in Approved Document F Volume 1: Dwellings (2021 edition) or are not less satisfactory than before the work was carried out. An example of this maybe when replacing a window in a room where there is already a wall ventilator present which meets the minimum equivalent areas in Approved Document F Volume 1: Dwellings (2021 edition). In which case no further trickle vents would need to be added after replacing the windows.

However, where there is an open-flued appliance in the room, there should be permanently open-air vents to supply the air for combustion. These air vents are there to meet Part J requirements and should not be considered as existing ventilation for Part F and therefore extra vents should be installed.

It should also be noted that if it's not technically feasible to adopt the minimum equivalent areas set out above, the trickle vents should have equivalent areas as close to the minimum value as feasible. In this situation, it is advisable to agree on this with your Local Authority Building Control Team (where applicable) in advance of ordering material and commencing works.

I live in a historic dwelling. What do I have to do?

Work to the following types of dwellings may not need to comply fully with the ventilation standards outlined in Approved Document F Volume 1: Dwellings (2021 edition):

Works on the above listed or historic dwellings should comply with the ventilation standards outlined in Approved Document F Volume 1: Dwellings (2021 edition) where reasonably practicable, therefore early engagement with the Local Authority Listed Building Officer and Building Control Surveyor is recommended if applicable.

Can I use a window with night-latch capability as a suitable substitute for trickle vents when replacing windows?

No. Providing a night-latch, where a window can be locked slightly ajar, is not a suitable substitute for trickle vents. This is because windows locked on the night-latch are not likely to provide an adequate level of security to be used as a permanent substitute for trickle vents.

Can I sign a disclaimer that I’ll install trickle vents at a future date or that they/I don't wish to have any installed when getting replacement windows fitted?

No. A disclaimer signed by you stating you do not wish to have trickle vents or that they will be installed in future is not a suitable way of complying with the Building Regulations, as all requirements must be met in full for the works to comply with the Building Regulations. 

What types of trickle vents are available?

There are many types of trickle vents available on the market, some of which are detailed below:

  • Through frame design - The trickle vent is often positioned through the head of the frame.
Replacement windows and trickle vents

Photograph 1: Through frame design trickle vent. Courtesy of ‘A guide to trickle ventilators’ published by Glass and Glazing Federation

  • Over frame design – On some occasions it is not possible to fit the trickle vent through the frame, therefore ventilation can be routed over the frame or head of the window.
Replacement windows and trickle vents

 Photograph 2: Over frame design trickle vent. Courtesy of ‘A guide to trickle ventilators’ published by Glass and Glazing Federation

  • Glazed in – Sometimes it is necessary to fit the trickle vent into the glazed area along the top of the sealed glass unit.
Replacement windows and trickle vents

Photograph 3: Glazed in trickle vent. Courtesy of ‘A guide to trickle ventilators’ published by Glass and Glazing Federation

  • Different framing materials – Trickle vents can be fitted in all window framing materials, including PVC-u, timber, steel, and aluminium.
Replacement windows and trickle vents

 Photograph 4: Trickle vent in timber frame. Courtesy of ‘A guide to trickle ventilators’ published by Glass and Glazing Federation.

  • Easily controllable – As trickle vents are usually situated above the window, some vents can be controlled by cords or rods or simply by hand.
Replacement windows and trickle vents

Photograph 5: An easily controllable trickle vent operated by hand. Courtesy of ‘A guide to trickle ventilators’ published by Glass and Glazing Federation.

For more information, you may also wish to read the frequently asked questions on Approved Document F, which is accessible here.

 

Please Note: Every care was taken to ensure the information was correct at the time of publication. Any written guidance provided does not replace the user’s professional judgement. It is the responsibility of the dutyholder or person carrying out the work to ensure compliance with relevant building regulations or applicable technical standards.


This article was first published on 24 November 2022

Comments

Kitchen/Living sub rule

Submitted 1 year 2 months ago

The sub rule states that the combined kitchen/living space must have 3 times the number of vents that you would find in a habitable room, but vents have different EA and tend to be around 4000-5000mm2 - i.e. not the 8000mm2 required for a habitable room... so does the regulation require:
a) 3 vents - totalling 12,000-15,000mm2 for the combined area, OR
b) 3 times the equivalent area required for a habitable room - i.e. 24,000mm2 ?

LABC Response

Submitted 1 year 2 months ago

Hi,

Thank you for your enquiry.

Clause 1.58 in approved document F volume 1: 2021 states: If the dwelling has a kitchen and living room which are not separate rooms, at least three ventilators of the same area as for other habitable rooms in Table 1.7 should be provided in the open-plan space. The minimum equivalent area of background ventilators for dwellings with multiple floors is 8,000mm2 and so three vents would have an area requirement of 24,000mm2.

Best,
LABC Team

Replacement windows prior to June 15 2023

Submitted 1 year 1 month ago

I had aluminium replacement windows installed by remedial contractors in april/may 2022 to replace upvc windows.
I have since been advised that the aluminium windows did not comply with building regs at the time of installation because they have been installed without any trickle vents at all even though the existing upvc windows had trickle vents in place.
Can you advise my next actions

LABC Response

Submitted 1 year ago

Hi,

Thank you for your comment.

The view of LABC is that it is a requirement of Regulation 4(3) of the Building Regulations 2010 for building work to be carried out so that it complies with the applicable requirements of the Building Regulations or where it did not comply with any such requirement it is no more unsatisfactory than before the work was carried out. So, with regards to omitting trickle vents from the replacement windows, you may take a view that the work has now resulted in the dwelling being less compliant with Part F of the Building Regulations than it was originally.

The following actions may be helpful to you to resolve your concern:
1) In the first instance, it may be preferable to contact the installer to agree a way forward.
2) Assuming the installer is registered with FENSA, you may be able to escalate to FENSA - see here for more info www.fensa.org.uk/Complaints.
3) Contact the Building Control team at your Local Authority - their contact details can be found by inputting your post code into the ‘search bar’ located in the top right corner of our website.

Kind regards,
LABC

Never supplied fensa certificate in 2019 install...

Submitted 12 months ago

Hi

We had all new windows and doors fitted in 2019 to a bungalow, I have photograph evidence (via metadata) of the date.
The fitter never supplied a fensa certificate even after much chasing, it later transpires he had a breakdown and disappeared from the face of the earth :-/

We would like BC to certify but it now longer meets the newer regulations for 2022. We have bi-folds where a large window was, with no vents in. The pre existing wooden window had no vents and I do have photos to that effect.
Vents of 3200ea are fitted in all of the windows but I gather these aren't large enough. The could easily be routed out to a larger size but the bi-folds do not look like that would be practical as it would have to be in the leaf. Could a wall vent be fitted if necessary instead?

As I can demonstrate the dates would this still have to come under the later regulations rather than the ones in force at the time of fitment?

Thanks

LABC Response

Submitted 7 months 1 week ago

Thank you for your enquiry.

LABC cannot comment on specific cases as that is a matter for your LA, however the regulations that apply are the ones that were in force at the time that the work was carried out, albeit the requirement for trickle ventilation has been in force for at least 35 years.
It is possible to fit an air brick in the wall and that should be discussed with your LA.

Best,
LABC Team

Work started before June 2023

Submitted 11 months 3 weeks ago

What classes as work started before June 2023. Would having a bat survey and the owner doing minor strip out be acceptable for “work started”

LABC Response

Submitted 11 months 1 week ago

Hi,

Thank you for your enquiry, the start of works relates to the actual commencing of parts of the Building Regulations and therefore a bat survey or minor strip out would not suffice. The works for replacement windows would therefore likely be taking out the existing windows.

Best,
LABC Team

Replacing wooden (with no trickle vents) with uPVC windows.

Submitted 11 months 3 weeks ago

If you replace wooden windows with no trickle vents, with replica ie identical new uPVC windows - where the ventilation will be the same ie not be made worse by the installation of the new energy-efficient - is that acceptable and would likely be approved by local building regulations?

LABC Response

Submitted 11 months 1 week ago

Hi,

Thank you for your enquiry, as our article outlines the replacement of a timber window with a modern UPVC window is likely to increase the airtightness of the dwelling. Therefore, to meet the regulations you should incorporate trickle vents in the replacement windows equivalent to the following:

Habitable rooms – minimum 8000mm2 equivalent area
Kitchen – minimum 8000mm2 equivalent area
Bathroom (with or without a toilet) – minimum 4000mm2 equivalent area

If your proposal, by a competent designer/engineer, shows that you have other means of background ventilation, (airbrick or wall ventilator) as sufficiently beneficial to the overall ventilation, then you would need to present that proposal to your LABC team where you live.

Best,
LABC Team

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