Why Do We Need Ventilation?
Ventilation in buildings is critical to maintaining healthy living spaces. As windows and doors are considerably more draught-proof, and buildings become more energy efficient, natural ventilation from outside fresh air is reduced.
In normal living conditions and day-to-day activities, moisture is created in the air. From showering, laundry, cooking and breathing a considerable amount of water can be produced on a daily basis. This moisture becomes trapped in the home and will start to form condensation on cold surfaces. Mould then starts to grow, which is significantly dangerous to health.
Allowing air to circulate from the outside to inside a building displaces moisture from the internal air.
There are different solutions for ventilation such as mechanical exchange units, but trickle vent background ventilators in windows and doors are the most common and simplest.
Read more: Why ventilation is important in your home...
The Main Types of Trickle Vents Include:
- Through Frame Design
The most common type of trickle vent used in modern window frames. The vent is fitted in the top of the frame and integrated with a staggered design to limit through draughts.
At Everest, our trickle vents are integrated into the frame using an ‘Up and Over’ design.
- Over Frame Design
If a vent cannot be fitted through a frame, it can be fitted over the top of the window frame.
- Glazed In
The least favourable type of background trickle vent because it detracts so much from the aesthetic of the window. The vent is fitted into the glazed area between the sealed glass unit and the frame profile.
At Everest, we don’t use Glazed In or Through frame trickle vents.
Can You Fit Trickle Vents to Existing Windows?
A trickle vent can be installed in existing windows, but for best results, we don’t recommend this at Everest.
Retrofitting a trickle vent is done by drilling through the existing frame. It’s not an easy job and if your measurements are not perfect then your frame will have big holes that you can’t fill!
To get the most efficient background ventilation in a window frame, the design of the trickle vent needs to be built into the window frame profile.
Do I Need Trickle Vents?
Building Regulation requirements for trickle vents are different depending on the age and type of property you have:
- Homes using mechanical ventilation and heat recovery are designed to be airtight and ventilation is provided mechanically. Trickle vents are not needed.
- Homes using continuous extract ventilation systems use a combination of mechanical and natural ventilation. Trickle vents must be installed.
- Existing properties without trickle vents when replacing windows must demonstrate that the new windows do not increase airtightness (unlikely). Or, the new windows must have trickle vents.
- Existing properties with trickle vents can replace the windows with at least the same size trickle vents, or more (but not less).
Most replacement windows will require trickle vents to be installed unless there is an exemption (see below), or the property can demonstrate sufficient levels of other background ventilation.
Read more: Size requirements and how many trickle vents are needed in windows...
Exceptions to Trickle Vent Installation
A house using mechanical ventilation with heat recovery should not install trickle vents under Building Regulations. Note that continuous mechanical extract ventilation does require the use of background ventilation.
Listed and historic buildings are exempt from the installation of trickle vents:
- Those listed in accordance with section 1 of the Planning (Listed Buildings and Conservation Areas) Act 1990.
- Those in a conservation area designated in accordance with section 69 of the Planning (Listed Buildings and Conservation Areas) Act 1990.
- Other historic buildings with a vapour-permeable construction that both absorbs moisture and readily allows moisture to evaporate. These include those built with wattle and daub, cob or stone and constructions using lime render or mortar.
Other exceptions to note are for houses adjacent to busy roads and susceptible to pollution. In those cases the size of trickle vents should be as high as possible and located on the less polluted side of the building. It is suggested that mechanical ventilation might be the better option.
What Choice Do Homeowners Have about Trickle Vents?
Some homeowners prefer a window frame without trickle vents. The most common reasons are:
- Aesthetic – window frames look better with clean profiles
- Dirt trap – the vents can be difficult to clean
- Noise – the gap in the frame can cause some noise to leak from outside
- Draughts – open vents can cause cold spots
Window frames do look better without a trickle vent, but the benefits of using trickle vents as part of a ventilation system in the whole house cannot be ignored.
Trickle vent design today is far better than early ventilator designs and modern trickle vents are seamless with the frame. Everest trickle vents have insect screens to stop tiny insects to keep bugs out and have an easy-to-clean design.
What cannot be avoided is that in many circumstances, the installation of new windows will require trickle vents to be fitted so that the window passes Building Regulations. At Everest, we cannot supply windows without vents where they are required.
If a homeowner was to fit windows without trickle vents when they are required, they might have an issue when trying to sell the house without full Building Regulations.
When buying new windows, make sure that you take advice from a registered supplier who can help you comply with regulations.
At Everest, we can advise you on what you need to ensure that all regulations are followed. We will provide you with a certificate that shows the work was completed by a registered supplier and that the windows meet Building Regulations.
The information above is provided as a guide only and correct at the time of publication: March 2023.
We recommend you read in full Building Regulations Approved Document Part F.
Building Regulations are subject to change. Always seek approval from your local planning authority before starting any building work.