The long-awaited revisions to Building Regulations have finally arrived and there are a number of updated regulations that are going to have a direct impact on the fenestration industry.

In this post, I am going to mark the noteworthy changes that have significance and try and explain what it means for us all. There will be a series of follow-up articles exploring the changes in more detail.

But for now, let’s just try and digest what these revisions are and how they will or won’t change what we do.

Part F – Ventilation

This is the one part of the Building Regulations changes that we have quickly got to know about over the past day or so.

In short, the new requirements are going to be that new windows going into existing dwellings (homes) or new dwellings will require trickle ventilation. Here is the wording from the newly published documents:

Background ventilators

1.52 All rooms with external walls should have background ventilators. If a habitable room has no external walls, paragraphs 1.42 to 1.44 should be followed.

NOTE: A window with a night latch position is not adequate for background ventilation, due to the following:

  1. The risk of draughts.
  2. Security issues.
  3. The difficulty of measuring the equivalent area.

Source: – pages 22/23

There is a loophole within these new rules. Mechanical ventilation systems or extractor fans can be installed in each room instead of windows. This is all part of the wider purge ventilation section of Part F which starts on page 19 of the document linked above. But that is simply not a realistic alternative. So trickle vents in windows remain the most viable and readily available solution for installers to abide by these new regulations.

Part L – U-Values

Another expected change was the lowering of minimum u-values for windows. At the moment that stands at 1.6 for new windows going into existing dwellings. New Part L regulations revise that down to 1.4. There was a suggestion at one point that it could be lowered to 1.2, which sparked debate about whether the use of triple glazing would be needed to achieve this.

These are the new minimum u-values for windows and doors:

Source: – page 25

Doors have also been moved 0.2 lower, from being at 1.6 previously. At 1.4 any decent double glazed window with the right glass and spacer bar mix should be able to achieve 1.4, which will mean this is no new dawn for the age of triple glazing.

I don’t think that many of us will have to worry about the u-values of swimming pool basins.

Part L – Airtightness

Here’s something that perhaps hasn’t hit some radars yet but will be of some significance to most of us and that is the revision of section 4.21 part h:

Part L Building Regulations U-Values table

Windows and doors: to ensure continuity of the air barrier, window and door units should connect to the primary air barrier and window and door frames should be taped to surrounding structural openings, using air sealing tape. Compressible seals or gun sealants may be used to supplement taping.

Source: – page 40

For those installers that fit a lot of their windows and doors into new-build homes and extensions, it looks like you’re going to need to get used to working with expanding sealant tapes or whatever similar alternative is out there.

Questions still to answer

This is a very brief rundown of what some of the major changes are in the revised Building Regulations. There are others that affect conservatories and porches which will be worth a read as well. But the three above I have highlighted as perhaps the most significant.

The one that has had many people talking on social media is of course the new requirement for trickle vents in all new windows to all existing and new dwellings. There have already been major pushback from the installer part of the sector, and indeed some fabricators I have already spoken to about it.

However vehement and passionate the protests, these do look set to the be new rules that come into force, unless there are some extremely unexpected revisions in the coming months.

There is however a number of unanswered questions that these new Building Regulations raise.

First, who is going to enforce these new laws? On the issue of trickle vents, it has already been pointed out that without rigorous and effective enforcement, a homeowner that doesn’t like trickle vents will simply go down the road to the company willing to flout the new rules, leaving the business willing to comply losing orders.

Second, what about the transition date? The Government has set June 15th 2022 as the date from which these new Building Regulations become law. But this would pose a very practical problem for both installers and fabricators. Many installers have three to four months worth of work already scheduled. It would mean that any orders sold in mid-February would need to be produced with trickle vents. This is a very short space of time and I would expect the Government to push back that June date to allow more time for the sector to adapt as needed.

Third, will the compliance schemes allow installers another way around registering installations with qualified background ventilation? There is a very high chance that many installers will not comply with these new rules. But will trade bodies really kick out all their members if they don’t follow the rules? No, that would cause chaos. Instead, they may decide that there could be another way to define background ventilation, to avoid what could be a very difficult and awkward situation.

As I have mentioned, these new Building Regulations have just dropped, and this is just my early analysis of them. In the coming days, I will issue follow-up articles to explore each of these changes in more detail and how they are going to affect our industry.

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