This project is presented by GRP Designs
Summary: Replacing and replacement windows and doors
Also see project on removing timber frames
In 2002 building regulations changed dramatically to keep energy in buildings as much as possible. From the roof to the floor, insulation requirements changed and this includes the windows.
The information in this project is brought to you by GRP Designs, who are one of the leading suppliers of replacement windows and doors and will be pleased to speak to you about any aspect of your plans for replacement windows and doors. Simply click on any of the links to get through to their website.
Replacement windows have come on leaps and bounds in the last 10 years. It is now possible to match almost any kind of window and door, including sliding sash windows and traditional looking composite doors. The latest range of replacement windows and doors provide excellent thermal properties, high security locking and low maintenance.
For many years, it has not been necessary to
apply for Building Regulation consent when replacing windows in existing
dwellings unless a structural alteration was involved. This usually only
occurred when the existing opening was being made wider (which made the
installation of a new support lintel necessary), or where the windows were
part of a structural bay.
Since the 1st April 2002 all owners replacing windows need to obtain consent,
and the new windows themselves will have to fully meet the requirements of the
Building Regulations. So even if you are
replacing only one window with one
bought from a local DIY centre you still need to follow the guidance below.
It is important that householders obtain the necessary consent as solicitors
will make a specific check for this when the property is sold.
What do I have to do ?
You have a choice, you can either -
1. Use an installer, such as GRP designs, registered under the FENSA scheme run by the Glass and
Glazing federation, in which case you do not need to make a Building
Regulations application to the Council. Your installer should then ensure your
windows comply fully with the Regulations and will supply you with a
certificate confirming this when the installation is complete. You will be
offered the option of taking an insurance-backed guarantee. Please ensure that your installer is properly
registered under the scheme before placing an order. You can check this and
find more details of the scheme by visiting the Glass and Glazing federation
web site at www.ggf.org.uk
2. Make a Building Regulations application to your local authority, and in
most cases the simplest way of doing this will be to submit a Building Notice.
You must complete the Building Notice form, and return it to them together with
the appropriate charge at least two working days
before removing the old window(s). If all is found to be satisfactory your
local authority will approve the work. This may involve a surveyor calling at
your property to check the installation of the new windows.
How much will it cost
?
If you use a contractor registered under the
FENSA scheme the cost should be built into the quotation for the works you are
given. In all other cases the Council will make a charge for dealing with your
Building Notice application based on the total cost of the work. Your local
Council will be able to tell you the charge for your scheme.
What regulations do
the windows have to comply with ?
Owners of listed buildings and buildings in Conservation Areas may not need to
satisfy these requirements in all cases. However, it is still necessary to
apply for consent through the local authority or the FENSA scheme. Please
remember that separate Planning Permission may be required from the local
authority.
Thermal insulation
The replacement windows & doors will need to meet the new thermal insulation
requirements of the regulations. If the replacement windows have wooden or
plastic frames, then the glazing needs to achieve a maximum U-value of
2.0W/m2K while for metal frames a slightly higher U-value of 2.20W/m2K is
allowable. Take great care when ordering new windows that your supplier can
prove the glazing units used will satisfy this requirement, as the Building
Control Officer will need to see this proof before issuing a completion
certificate. We would particularly recommend that you leave any labels on the
glazing in place until after a satisfactory inspection has been carried out by
the Building Control Officer. Below are examples of typical construction
details which meet the new requirement.
| Glazing in timber or plastic frames |
U- value 2.0 | Double glazing with
16mm air gap and a soft low-E coating; or, Double glazing with 12mm air gap, argon filled and a soft low-E coating |
| Glazing in metal frames | U- value 2.2 | Double glazing with 16mm air gap, argon filled and a soft low-E coating |
In some cases it may be permissible to use glazing units which do not meet the
above specifications, but to do so you (or your supplier) would have to submit
calculations to prove that the overall insulation requirements of the
regulations would still be met. This may be possible if other insulation
measures are undertaken at the same time as the window replacement - for
example, installing cavity wall insulation or "topping up" loft insulation.
The benefits gained by installing this extra insulation can be used to offset
the higher losses through the glazing, but this should not be undertaken
lightly. We would strongly advise you get any such calculations checked by the
Building Control Officer well before the replacement windows are installed, so
that expensive mistakes can be avoided.
Building Control Guidance Note
Subject Replacement Windows to Existing Dwellings
Issued 01/06/02 Rev A
Means of escape
All first floor windows in dwellings should ideally have opening lights large
enough to allow you to escape through them if you were trapped in the room by
a fire. This also applies to rooms in bungalows, which open into a hall
(unless the hall itself has an external door through which you could escape).
To meet this requirement all such windows should have an unobstructed openable
area of at least 0.33m2 and be not less than 450mm high and 450mm wide (the
route through the window may be at an angle rather than straight through). The
bottom of the openable area should be less than 1100mm above the floor. Talk to GRP designs about escape windows.

If your existing windows do not have opening lights which meet
the above requirements, we would strongly recommend for your own safety, that
you take the opportunity to provide them in the replacement windows. This is
not however a requirement of the regulations, which simply state that the
replacement windows must be no worse than those they replace in this respect.
Where the existing windows already have opening lights which are larger than
the above requirements, those in the new windows can be reduced in size
provided they are not reduced to less than the dimensions above.
Safety Glazing
Low level glazing (glazed areas within 800mm of floor level) and glazing in
doors within 1500mm of floor level should generally be of a type so that if
broken, it will break safely. In practice this means
such glazing should be
either laminated or toughened. Ordinary glazing can still be used in small
pane sizes however, provided the glass is sufficiently strong to resist
breakage. The Approved Document to part N of the Building Regulations gives
maximum sizes according to the thickness of glass - for example, in a single
pane less than 1.1m square - 8mm glass would be satisfactory.
Structural safety
If the replacement windows are wider than those they replace, or involve the
replacement of bay windows, then proper structural support is required above
the window. In older buildings, the timber frame of the window was often
sufficiently strong to carry the load of a wall or roof above it without a
lintel. Obviously in these cases either a lintel needs to be installed when
the window is replaced, or the new frame carefully reinforced to carry the
load. Further advice on structural stability can be obtained from your local
authority.
Ventilation
The Building Regulations require that adequate ventilation is provided for
people in the building and this should be considered when deciding on the size
of opening lights in the replacement windows. For most rooms, one or more
opening windows totaling 5% of the floor area, with background "trickle"
vents totaling 8000mm2 will be adequate. For kitchens, utility rooms and
bathrooms an extract fan is also normally required. In some cases the existing
windows may contain a permanent vent to supply combustion air to a heating
appliance, although this is now rare. If this is the case however you should
ensure that either the replacement window contains a similar permanent vent,
or that some other means of providing the required ventilation is installed at
the same time.
If you have or you are looking into replacing your windows it may also be worth looking into replacing your doors as in most cases the two jobs can go hand-in-hand. For strength, security and pure good looks you would be hard pressed to beat a composite door from GRP designs.
Many window fitting and replacement companies also cover door fitting and replacement so if you are going with an external company to replace your windows then it may be worth your while asking about replacing your doors at the same time as they will be able to provide you with a quote for the whole job, including the necessary consent for building regulations from your local authority (as replacing an external door is also covered by these regulations).
If, however, you have decided to replace an external door yourself then you will need to follow the steps mentioned above in order to obtain the afore mentioned consents from your local authority before you can start any work.
Once you have confirmation that you can now go ahead and start work, the first task is to measure your door so you know how big your new door needs to be. Use the diagram below as a guide on how to accurately measure a door:
The image on the left demonstrates how you should measure the width of your door. You should measure in 3 places, top, middle and bottom and use the smallest amount as the width.
The image on the right demonstrates how to measure the height of your door. Again this should be done in 3 places, far left, far right and in the middle. As for the width, the smallest amount is used as the total height.
Now that you have the correct measurements to work to you can now purchase your new door. The majority of new doors today come with their own frames. It is always better to replace the frame as you can then be sure that it is up to the task of holding your new door (as your new door may be a lot heavier than your existing door and if your frame is old and worn, it may not have the strength to support the new door).
Composite doors from GRP Designs combine the traditional look and feel of a wooden door with the huge advantage of security and maintenance guarantees plus insulative qualities which easily meet any regulation requirements.
By replacing the frame this will also provide you with added security and also make your home more energy efficient in that it will provide a better seal and prevent draughts and heat loss.
Depending on whether you have opted to go with a solid wood door or a upvc, this can have some bearing on how extensive a task replacing the door will be. Either way, you may be required to pack out the new frame with chocks to ensure that you have a decent and snug fit.
Once you have fitted your replacement door you will then have to think about security. Many upvc doors come with their own means of security e.g. they come fitted with locks etc.... If you have opted for a solid wood door then many of these do not come with their own security measures installed, but many of them do come with the relevant installation points already cut out so in most instances it is just a case of fitting them.
Much more construction information is available in our bookstore. All the tools and fittings you need in the toolstore.