Part F Background Trickle Ventilation Calculations

What is a background ventilation calculation?

Current building regulations (Part F) require you to demonstrate the dwelling has sufficient background ventilation. This is commonly known as trickle ventilation and usually achieved using vents installed in window frames when the property is mechanically ventilated using either intermittent or continuous extract fans. If the dwelling has a whole house ventilation system such as Mechanical Ventilation with Heat Recovery (MVHR) the property shouldn’t have any background ventilators.

combine your trickle vent calculation with

your SAP calculation and save £££'s

What are the requirements?

The amount of background ventilation requires depends on several factors including the type of mechanical extract ventilation, size of the property, number of bedrooms and the design air permeability rating.

The calculation should be provided to the building inspector prior to commencement onsite. Once the calculations have been completed, these should be provided to the window manufacturer to ensure the correct amount of trickle ventilators are installed into the window frames.

What do trickle vent calculations cost?

The most cost effective method is for us to provide the background ventilation calculation at the same time as the SAP Calculation. Below is a schedule of typical fees for providing the background trickle ventilation calculation with or without the SAP calculation. Prices are per plot (Ex VAT).

Property Type
With SAP Calculation
Stand Alone
Flat (under 75m2)
£30.00
£50.00
Small House (under 100m2)
£40.00
£60.00
Medium House (under 200m2)
£45.00
£65.00
Large House (under 300m2)
£50.00
£70.00
Extra Large (over 300m2)
£75.00
£95.00
Express Service (Same Day)
Fee + 50%
Fee + 50%

How we can help?

One of our experienced assessors can calculate the requirements for your project and where required provide advice on the size, specification and quantities required to ensure compliance. We typically assist in either of the following stages:

Building Regulation Approval (Design Stage)

We are able to undertake a full review of the architectural drawings and provide a complete schedule for the amount of background ventilators required to achieve compliance with the requirements of Part F of the building regulations. If for any reason the proposed drawings or specifications fail to deliver compliance we will provide helpful advice for a practical solution. Upon completion of the calculation you will be provided with a PDF report which can be used for submission to the building control body for approval.

During Construction

Depending whether you submitted evidence of the background ventilation at a pre-commencement stage, you may require assistance with checking that the window manufacturers have provided the correct amount of background ventilators. If you use us for the design stage calculations we can assist in the same way as above and provide you with a detailed report confirming your requirements and how they can be achieved. You will be provided with a PDF report which can be used to submit for discharging any building regulation conditions.

Why Use BEAT?

BEAT Solutions are experienced in produced Part F Background Trickle Ventilation Calculations having worked on hundreds of projects and thousands of dwellings. This level of experiences enables us to offer years of product knowledge and helps ensure a desirable compliant outcome for the project.

Very professional advice, friendly prompt service. Quick delivery of all certificates needed to complete building project.

B Foster - Farnham

When should I get the background ventilation calculation?


The background ventilation calculation should be preformed prior to submission for building regulation approval. Failure to do so may results in non compliance during the construction works. This may results in incorrect sizing of trickle vents and expense replacement costs.




How do i recieve my calculation?


The calculations are provide in PDF format for easy distribution.




What do we need to undertake a background vent calculation?


We require drawings including floor plans, sections, elevations and site plan. Additionally we'll require a copy of the design stage SAP calculation to establish the design stage air permeability score.




What happens if my current drawings, specification or proposal fail compliance?


We are focused on helping all projects succeed. Therefore if your property fails to deliver the correct amount of trickle vents we'll provide helpful advise and a practical solution in order to help gain compliance.




How to i get a quote?


Just send us your project drawings via email to info@beatsolutions.co.uk or use our quote request form and we'll send you an electronic quote by return.




How long does take to recieve the calculations?


Depending on the size of the property the calculations are turned around within 2-3 days. If you require a more prompt service we offer a Express Service. The express service is chargable at and additional 50%.





Frequently Asked Questions