| Replacement Windows Building
Regulations - England & Wales - in association with
WindowsToday.co.uk
Document L of Building
Regulations
All replacement window installations in England
& Wales are subject to BUILDING REGULATIONS. This regulation
in particular affects the minimum levels of insulation that replacement
windows must have when fitted in your home. Levels of insulation are
measured as U values. The lower the U value, the better the insulation
level. In future what we may have in the past have referred to as "normal"
double-glazing - i.e. two pieces of glass separated by a spacer bar is
very unlikely to conform to building regulations. To get the required
level of insulation it's almost certain some sort of LOW E glass
(typically Pilkington K in the UK - although there are other brands) will
have to be used. It may also be necessary for the sealed double glazed
units to be Gas Filled (probably Argon).
FENSA
self-certification scheme
There are two ways that you can
ensure compliance with relevant regulations, firstly you may employ a
contractor or installer who is registered under the FENSA
self-certification scheme. This contractor will be approved to carry out
the work in accordance with relevant regulations without inspection by the
council and will inform FENSA when installation has been completed. Random
inspections of completed work are carried out.
In addition to Building Regulation consent you must
ascertain whether or not planning permission or conservation area consent
is required. The Development Control section of the council can advise you
on this.
If you are not using a FENSA registered
contractor or if you're doing the work yourself then you will need to
arrange building regulation approval yourself.
In short this means you need to be able to confirm the
following:
 |
The replacement
will achieve a U-value of 2.0 W/m2k for PVC or timber frames, or 2.2
W/m2k for metal frames. |
|
Glazing within
critical locations will be replaced with safety glass. |
|
Existing
measures for background and natural ventilation will be
retained. |
|
Existing
measures for means of escape from relevant rooms will be retained.
(If the window pattern is to be changed this may affect means of
escape). |
|
Open flue
appliances affected by the window/door replacement will be checked
for adequacy of combustion air supply by a suitably qualified
person. |
|
If necessary, a
suitable means of support will be provided above the replacement
window/door. |
|
Where the
dwelling was required to be constructed to provide an easily
accessible threshold at entrance doors this will be
retained. |
Replacement Windows and
Doors
As from 1 April 2002, Building Regulations request that
building owners installing replacement windows or doors must obtain
Building Regulations consent and have the installation inspected to ensure
compliance with relevant regulations. The relevant regulations
are:
L1 Conservation of fuel and power
N1 Glazing
protection against impact
In addition, you
must also ensure that replacement windows and doors are no less suitable
than the existing windows and doors in relation to the following
regulations:
A1 Structure
B1 Means of
escape in fire
F1 Means of ventilation
J2 Combustion
appliances and fuel storage systems
K2 Protection from
falling
M2 Access and facilities for disabled
people
Repair work, such as replacement glazing
or repair of rotten or damaged frame members is not subject to Building
Regulation approval.
Guidance on how to satisfy the
requirements
Requirement
A1-structure.
When installing new windows or doors an
assessment should be undertaken by the contractor as to the suitability of
the support of lintel above the replacement window or door.
Requirement B1- means of escape in
fire
All windows to habitable rooms (but not kitchens,
utility rooms, dressing rooms, bathrooms, wc's or shower rooms) at floors
above ground level are required to be3 suitable for escape in fire. In
addition, rooms at ground floor level whose only escape route is via
another room must be provided with suitable escape windows.
A suitable
escape window is defined as 'a window whose unobstructed openable area is
alt least 0.33m2 and at least 450mm high and 450mm wide (a 450mm wide
opening will need to be 735mm high). The bottom of the openable area
should be no more than 1100mm above the floor. Any key required to open
the window should be readily available.
F1-means of ventilation
See table 1 below
for current requirements. If your original windows have trickle
ventilators any replacement frames should also be provided with such. The
area of opening windows should not be less than that which was originally
provided.
As and alternative approach to the ventilation provisions
listed in table 1 below, the overall provisions for background
ventilations for the dwelling should be equivalent to an average of
6000mm2 per room for the rooms listed, with a minimum provision of 4000mm2
in each room.
Table 1 Ventilation:
current requirements for various rooms
| Room |
Rapid
ventilation |
Background
ventilation |
| Habitable room |
1/20th of the floor area
of the room served |
8000mm2 |
| Kitchen and
utility |
Opening window
(No
minimum size) |
4000mm2 |
| Bathroom/Shower
rooms |
Opening window
(No
minimum size) |
4000mm2 |
| Sanitary
accommodation |
1/20th of the floor area
of the room served |
4000mm2 |
J2 Combustion
appliances and fuel storage systems
Certain fires and
heating appliances relay on air infiltration for them to function
correctly. They may require purpose made ventilators, or may have relied
on air infiltration through existing ill-fitting windows and doors, If you
have an open flued appliance in the house that does not have separate
provision of combustion air, a check should be made by a suitably
qualified person (CORGI, HETAS, NACE, NACS, etc) to ensure that adequate
permanent combustion ventilation is provided.
The boiler or
fire manufacturers manufacturer's advice should be followed with regard to
proximity of opening windows and doors.
K2 - protection for falling
Where a first
floor window cill height is less than 800 mm above the floor level
suitable guarding should be provided to prevent a person falling through
an open window.
This requirement may conflict with Regulation B1 and
provision of escape windows. One way of achieving the requirement may be
to provide a restricted opening device that can be easily overridden in
the event of an emergency.
L1- conservation
of fuel and power
All UPVC and wood replacement windows
should attain a U value of 2.0W/m2K.
One way of achieving this
requirement is by providing a UPVC or timber double glazed window system
incorporating a 16m air gap between panes and an approved low emissivity
coating such as Pilkington K. This is not the only option, but if another
system is used, substantiation may be required to prove that a U value of
2.0W/m2 is attained.
M2 - access and
facilities for disabled people
Where the property was
subject to the Disabled Regulations, any new principal entrance door
should have a minimum 775mm clear opening with a low
threshold.
N1- glazing protection
against impact
Glazing should either:
|
Break safely as
defined in BS 6206:1981 Specification for impact performance
requirements for flat safety glass and safety plastics for use in
buildings, clause 5.3 |
|
Be inherently
robust, i.e. annealed glass, glass blocks, polycarbonate or glass
that gains strength through thickness. |
|
Be in small
panes (a maximum area of 0.5m2 with a maximum width of 250mm is
acceptable). Annealed glass should be not less than 6mm thick,
except where it is in traditional leaded- or copper- lights in which
4mm glass is considered acceptable when fire resistance is not a
factor. |
|
Be permanently
protected by a suitable screen which has a minimum height of 800mm
and which incorporates a gap no greater than
75mm. |
Diagram 1
Glazing in
Windows, Partitions Glazing in Doors and Side Panels and
Walls
Diagram 1 gives examples of glazing in
windows, partitions, walls, doors and side panels. 'Critical locations'
are shaded grey. Any glazing within a shaded area must comply with BS
6206.
In Diagram 1, glazing unit No. 10 falls wholly within a
'critical location' and so the glazing must comply with BS
6206.
Where only part of a glazing unit falls within a 'critical
location' the whole of that unit must comply with BS 6206. In Diagram 1
this applies to units Nos. 2, 3, 5, 6, 7, 9, 11 and 12.
In Diagram
1 only glazing units Nos. 1, 4 and 8 fall wholly outside the 'critical
location' and need not comply with BS
6206. |
