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This edition of the Blog comes following several recent experiences we have had with various new-build residential clients and mainly their Natural Ventilation Systems (Background Ventilators and Intermittent Extract Fans).

We’ve found that their projects are reaching completion and suddenly they are struck with a need to comply with Regulation 42 and Approved Document F of the Building Regulations. This results in potential delays and additional costs are introduced due to their unawareness around the necessity to comply.

Who’s fault is it?

Well that’s hard to say, there are numerous stakeholders who could advise throughout the project.

However, what is easy to say is the results are frustration and heart ache when the installed ventilation systems do not meet the required standards, or worse still concessions against poorly ventilated dwellings which could result in serious issues in the future.

Alex Tonge, Director

Everyone knows when building a new-build residential building in the United Kingdom (UK), you must comply with Regulation 42 and Approved Document F of the Building Regulations. So what’s the issue, right?

Well everyone doesn’t know.

Let’s step through a worked example of what we usually experience,

Ring… Ring…

Client: “Hello we’ve got this number from your website and we need your help, we need to get our fans tested so we can get the completion certificate from our build control, how soon can you be here and what will it cost?”.

During the initial phone conversation, we will run through some initial questions with them and ascertain what ventilation system they have installed (9/10 times this will be a Natural Ventilation System if they are not aware of the need to comply) and when they require the testing to be completed by. Finally, we then offer some best practice installation guidance and request that they then check this guidance against their installation, before highlighting any issues back to us in advance of our site visit.

Usually what happens is the client may spot some issues but hopes they will achieve compliance and asks we attend site to test at the earliest opportunity.

We then provide a quotation for the required services and arrange a test date.

The test date arrives…
On site visit and during the initial pleasantries, we’re usually met with a statement along the lines of: Client: “We didn’t know anything about this test until our build control told us on their final inspection”, and/or “we’ve never had to do this before when we’ve built previous houses, has it been in the regulations long?”.

Deep breath…

At this point our test engineer will usually start to lay the foundations for the disappointment that is about to follow (well most of the time anyway) and explain how the dwelling (and the extractor fans) will be inspected and tested to ensure compliance.

As these enquiries usually relate to a Natural Ventilation System, Background Ventilators with Intermittent Extract Fans (if background ventilators have even been installed that is!). We often find that this is the first stumbling block! This is the lack of understanding around what a background ventilator does – e.g. a trickle vent. The next issue usually results in the specification of the intermittent fans and poor installations which result in the fans not achieving the target flow rates (l/s) set out in Approved Document F.

Examples we encounter that are not uncommon are:

  • No external extraction in the kitchen – recirculatory cooker hood
  • The wrong specification of intermittent fan has been installed such as; a bathroom spec fan in a utility or kitchen wall
  • Ceiling mounted fans that are not designed to be installed with vertical ducting
  • The incorrect use of flexible duct; long lengths that haven’t been pulled taught or supported, that haven’t been insulated in unheated spaces, that are crushed, that are inadequately sealed, etc.
  • Poor installation of rigid ducts – long duct runs, bad seals on the joints
  • No insulation installed on the ducting in unheated spaces
  • Tight bends to external grilles installed in the soffits
  • Grilles that aren’t appropriate in comparison to the duct (with a free area of 90% of the duct size)
  • Etc.

Note: This is a personal bug bear of mine, and why I think this method of ventilation is no longer/ it never was appropriate for new-build residential buildings. People do not understand that a background ventilator is the primary ventilation for the dwelling and not the intermittent extract fans. This leads to insufficient amounts, inappropriate usage and worse still none being installed at all. Check out a previous blog, on what we do feel are appropriate methods of ventilation here.

We’re then met with the following statements from our client:

“That’s unbelievable, I can’t understand why they would be so poor”
“Well that’s not very good, what can we do about that to get it to pass”
“Why has nobody told me about this?!”

We then begin to diagnose what might be causing the issue (this is above and beyond our scope of work that has been quoted) and most of the time it is down to poor planning, design and the beforementioned installation errors, particularly on ducted systems. Generally, the client can’t believe their eyes and understandably they become very frustrated, as in the worst cases this can result in intrusive remedial works.

Following the completion of the inspection we then allow for remedial works to take place and a return visit to site to retest and hopefully achieve a compliant and successful outcome.

So how do we think this dreaded scenario comes about?

I place the fault on every stakeholder as broadly there is a lack of awareness and drop points on a number of fronts.

Usually if we were to look at the technical drawings for a dwelling, there would be information documented about where fans should be positioned (indicative) and the flow rates they need to achieve in those locations, with references made to Approved Document F of the Building Regulations and even regulation 42.

However, it’s then how does the information get picked up and incorporated into the construction of the dwelling from here on?

  • The architect may have only been contracted for the building regulations/technical drawings and not the project management of the construction phase – so they do not follow it through to completion.
  • The build control authority may not see it as their responsibility to educate the contractor or builder on how to build a dwelling, they are there as quality control evaluators, to ensure the building regulations and other applicable guidance is followed and incorporated – they could point to the fact that all the guidance is listed in Approved Document F after all!
  • The main contractor may trust that their sub-contractors are aware of the regulations and what is required of them to ensure the ventilation system is compliant.
  • The sub-contractor is just installing a fan – how hard can that be right, they’ve just got to pop down to the electrical wholesaler, buy the fan unit and fit it. They’ve done hundreds if not thousands before and never been picked up on it and build control have never asked for this testing before.
  • The self-builder if project managing the build trusts the parties they are instructing and paying, know what needs to be done to meet compliance with Approved Document F.

Hopefully you will agree that there are multiple chances for the responsibility to drop between each party’s role and responsibilities and furthermore there may just be a general lack of knowledge in industry.

What do we feel can be done to solve this?

It may be true that ultimately the party responsible/contracted for sign off and obtaining the completion certificate from build control is responsible. However, should these instances of non-compliance fall solely at their feet?

Well in some respects a cynic could say ‘yes’ they should ‘read the regulations’, however, we feel those parties who have the opportunity to say something should throughout the construction process. The Building Control role is well placed to support here, although it may not technically be their responsibility, by raising an awareness at an early stage of the project that compliance to Regulation 42 and Approved Document F is required for sign off they can signpost the potential issues of ignoring this and advise that the Client seeks expert advice. This could then prompt a Client to engage a ventilation specialist, such as Ecotest, and we can then ensure that a dwelling is optimally ventilated. We can discuss the systems available and support the client in providing a ventilation system that will meet the needs of Regulation 42 and Approved Document F and provide a healthy home for its future occupants.

How can we help?

Contact us and we would be happy to have a conversation about the optimal ventilation solution to suit your budget and project.

Please always remember that it is essential with ventilation systems that the system is designed, supplied, installed, and commissioned by a competent person.

That’s why we’re ceasing to offer Ventilation Flow Rate Testing Services

That’s why we have now chosen to remove the mechanical ventilation flow rate testing of natural ventilation systems from our services. However, the main reason was that we simply do not believe that today’s residential new-builds should have them, rather, they should have Continuous Mechanical Extract Systems as a minimum standard and ideally Mechanical Ventilation with Heat Recovery.

Thank you for taking the time to read this blog.

Published On: August 29th, 2023Comments Off on Intermittent Fans could lead to intermittent complianceCategories: Ventilation Flow Rate Testing, Ventilation Solutions