Building Regulations, Document L, FENSA, England and Wales
Since the 1st of April 2002 all replacement window installations in
England & Wales have been subject to building regulations. This regulation
in particular affects the minimum levels of insulation that replacement
windows must have when fitted in your home. A self-assessment scheme
has been set up for companies to enable them to serve their customers
without having to apply for building regulations applications for each
separate client. This scheme is called FENSA.
Scotland Building Regulations:
Please see http://www.windowstoday.co.uk/part_j.htm
N Ireland Building Regulations:
Please see http://www.windowstoday.co.uk/document_l.htm#nire
Planning Permission: It is your duty to check
whether you will need planning permission in order to have
your new windows installed. Especially if you live
in a conservation area or own a listed property you will have to double
check with your local council whether the windows of your choice
will be allowed.
If you don’t ask for planning permission you might have
to revert everything back to its original state, with all the
it brings. (Planning permission
is not the same as building regulations approval)
If you want to install your own windows or if your builder is not a
member of FENSA, then either of you needs to pay for the application.
It might take some time to get approval depending on your council.
As mentioned above one of the main reasons for the change is the need
to reduce energy loss. Levels of insulation are measured as U values.
The lower the U value, the better the insulation level.
The minimum U values
- PVC-U or timber replacement windows should not have a U value higher
than 2.0 W/m 2K
- Metal windows (Aluminium) replacement windows should not have a U value
higher than 2.2 W/m 2K
The Building Regulations had controlled glazing in new
many years but they represent only a very small percentage of the total
building stock in the UK.
Why did Doc L come about?
There are a number of reasons but perhaps the most important reason
was because of the Kyoto Protocol.
The Kyoto protocol was signed at the earth summit in Kyoto, Japan. The
British government and many other governments signed up to a reduction
in carbon dioxide emissions to the pre 1990 level. The British government
is committed to reduce carbon dioxide to pre 1990 levels by the year
2010 and to continue to reduce emissions, which cause global warming.
It was therefore essential to improve the performance of the much larger
numbers of existing buildings if we were to meet increasingly stringent
national and global energy saving targets.
Compliance - Special Note
When the time comes to sell your property, your purchaser's surveyors
will ask for evidence that any replacement glazing installed after April
2002 complies with the new Building Regulations. There are two ways to
prove compliance: -
1) A certificate showing that the work has been done by an installer
who is registered under the FENSA Scheme
2) A certificate from the local authority saying that the installation
has approval under the Building Regulations.
The FENSA Scheme
It is estimated that around 2 million installations of replacement
glazing happen every year. If all of them went through the normal Building
Regulations application process it would place an enormous burden
It was therefore essential to have a way to ensure that the work is
done properly without an unreasonable increase in the administrative
and financial burden on installers and property owners.
The answer was a scheme, which allowed installation companies that meet
certain criteria to self-certify that their work complies with the Building
The scheme is known as FENSA, which stands for Fenestration Self-Assessment.
FENSA was set up by the Glass & Glazing Federation, in association
with all key stakeholders, and meets with central Government approval.
A sample of the work of every installer will be inspected by FENSA appointed
inspectors to ensure standards are maintained.
FENSA will also inform local authorities of all completed FENSA installations
and issue certificates to householders confirming compliance. NB – it
is essential that on completion of your installation that you get from
your installer a certificate confirming all work done comply with the
building regulations. We have had a lot of reports of this not happening
and for sure this will build up problems for the future – especially
when it comes time to sell your property.
Any installation done by a firm which is not registered to self-certify,
or done as a DIY project by a householder, will need full local authority
approval under the Building Regulations.
Local authorities will know of all the approved installers in their
areas and will be able to identify unauthorised work very easily.
You should note that you, as the house owner, are ultimately
responsible for ensuring the work complies with the Building Regulations.
To comply with the U Values above the usual basic requirements are:
For PVC or wood units a 16mm gap with low E glass.
A wide option in respect of glass and frames is offered and manufacturers
details should be studied.
Trade off's can be used to substitute lower U values for walls etc against
glass percentage lower than 25%.
Attention will be required to ensure that air paths into buildings are
sealed by such methods as mastic around frames, expanding foam if suitable,
edges of warm deck roofs insulated and sealed, pipe entry to buildings
There are also requirements for ventilation, fire escape and safety
glass that the replacement glazing must meet. There is an excellent article
on the both the U Values and other compliance issues at http://www.double-glazing-uk.co.uk/Englandwales.asp
Before you replace your windows, be sure to ask whether the installer
is able to self-certify. If not, either they, or you, will need to make
an application to the Council for approval under the Building Regulations
and pay any relevant charges.
The Building Regulations: answers to your questions on Approved Document
There are many new features in the changes to the Regulations and the
new Approved Documents that will be unfamiliar to designers, builders,
building services contractors and building control inspectors alike.
Local authority Building Control departments are a traditional source
of help on how works can meet the regulations. To give assistance to
them in this role, and to help others directly, the Office of the Deputy
Prime Minister (ODPM) has asked BRE to operate this Frequently Asked
Questions site as a means of delivering answers to the questions that
are being raised.
FENSA Limited is the Fenestration Self-Assessment Scheme for companies
that install windows and doors in dwellings. This site supplies information
about the Scheme for both installers and the general public.
British Fenestration Rating Council - Rating windows and doors to save
The BFRC is dedicated to the operation of a UK national rating
system for the thermal performance of fenestration products. The rating
that we have developed must be "fair, accurate and credible" and
information about the system is given on their website.
A number of very interesting downloads (PDFs) are available from their
website - including:
Image Credits: Nuglas, Dial