How to take the dimensions of a window?

Knowing how to take the measurements correctly is essential to order a custom-made window online. It is also a step that many people dread, probably for fear of ordering a joinery that will not be suitable. However, it is something that is within the reach of any do-it-yourselfer and by following this guide we will explain, step by step, the procedure to follow.

Summary of the article

The taking of the dimensions depends on the type of pose

The measurement of the dimensions strongly depends on the way the joinery will be installed, that is to say the type of installation. There are mainly 3 of them :

• The applied installation, when the wall is insulated from the inside. The joinery comes to rest against the interior wall, and the thickness of the frame (which is called the frame), is planned to adapt to the thickness of the insulation that you are going to lay. It is a type of installation that is mainly found in traditional new buildings (brick or cinder block) or during major rehabilitations ;
• In the tunnel installation, the joinery is laid in the thickness of the wall ;
• A variant of the tunnel installation is the rabbet installation; the window or the bay window is housed in a notch provided in the wall. This is a very common technique in old houses ;
• The installation in renovation, the new window comes to be screwed on the old wooden frame which is preserved. Covering wings and coverings cover and conceal the old wooden frame.? This makes it possible to reduce the impact of the work in the home and to allow a faster installation ;
• The reno pose is also a little diverted to do what some call a flush tunnel pose, that is to say that the joinery is not positioned in the middle of the wall but at the inner limit (we call this the inner nude). The covering wings make it possible to make an aesthetic finish all around the window.

Do not hesitate to consult our guide to determine the most suitable type of installation for your configuration.

The necessary tools

The meter will be your indispensable tool. Also bring a pencil and a sheet of paper on which you will write down the dimensions. Do not forget to note which piece each joinery corresponds to, this will simplify things for you later and will make it possible to clearly identify where each of them goes.

If you are changing the windows in a very old house, provide a spirit level to check the level and plumb of the openings. It is not uncommon to find yourself with some surprises; the constructions of yesteryear are not always as straight as those of today. The joinery that you will receive is perfectly square and if your opening is not. For an applique installation, this does not pose a problem. On the other hand, in a tunnel, this defect can interfere during installation. The solution will probably be to cut a little into the wall in order to have a square opening, or to provide a larger set of installation (we will talk about this later).

Taking the dimensions of a window, the step-by-step method

Let’s get to the heart of the matter with some general considerations. It is always necessary to take the dimensions in 3 different places, both in width and in height. this makes it possible to verify that the opening is straight and square and it makes perfect sense in an old house. If you notice a discrepancy, remember the smallest of the 3 dimensions.

For all windows (except the fixed window) you will be asked for the lightening height. This corresponds to the height between the finished floor and the bottom of the opening, that is to say the height of the part of the wall that will be under the window. This dimension is important in order to position the handle at the correct height and that it is accessible, even by people with reduced mobility.

How to take the dimensions for an applique installation

For an applique installation, the dimensions to be filled in are those of the finished painting including exterior coating. In the case of a new construction, you must therefore take into account the thickness of the coating or cladding.

You need to raise 3 dimensions :

• The height of the finished table ;
• The width of the finished table ;
• The lightening height in the case of an opening window.

On your dimension statement, also write the desired opening direction as well as the frame size corresponding to the insulation that you are going to place on the wall, this information will be requested during the simulation.

Attention, the size of the frame must include both the thickness of the insulation but also the interior finish such as the BA13 plate. Be careful, because some configurations require a frame size sometimes larger than you think, for example for a bay window. On the same part of the wall you must have identical frames. Do not hesitate to make simulations on our website to find out the suitable frame.

As the joinery is placed as an applique against the interior wall, its manufacturing dimensions will therefore be slightly larger than those that you provide.

How to take the dimensions for a tunnel installation

For a tunnel installation, the dimensions to be filled in are the dimensions of the back of the frame. The joinery is placed inside the opening and you must deduce from the size of the hole what is called a set of installation so that the joinery can enter without forcing. To do this, take down the dimensions of the table (including the outer coating) and deduct 5mm in height, on the left and on the right.

You need to raise 3 dimensions :

• The finished table height, to which you deduct 5mm ;
• The finished table width, to which you deduct 10mm ;
• The lightening height in the case of an opening window, to determine the height of the handle.

Also note the desired opening direction because you will be asked for it for the simulation.

The joinery will be manufactured to the exact dimensions that you specify.

How to take the dimensions for a rabbet installation

The rabbet is a notch in the wall that allows you to embed the frame of a window. We often find this type of installation in old houses and it makes it possible to gain brightness because there is a larger glazing area. When you make a total removal of the old joinery, you can install the new ones in the same way.

It is actually a tunnel installation but instead of positioning the joinery in the middle of the wall, it comes to position itself in this notch. The dimensions to be noted are therefore those on the back of the frame which correspond to the so-called rabbet bottom dimensions from which you will deduce a set of installation so that the joinery can enter without forcing (5mm in height, 5mm on the left and 5mm on the right).

For a rabbet installation, you must note 3 dimensions :

• The height of the rabbet bottom, to which you deduct 5mm ;
• The bottom width of the rabbet, to which you deduct 10mm ;
• The lightening height in the case of an opening window, to determine the height of the handle.

Also note the desired opening direction. The joinery will be manufactured to the exact dimensions that you specify.

In our configuration tool, for rabbet installation, you must choose the tunnel installation and fill in the dimensions of the back of the frame, that is to say the dimensions of the bottom of the rabbet to which you will have deduced the set of installation.

In this type of laying, you should pay attention to the thickness of the new profile compared to the old one. If the old wooden windows had frames of 50mm or 60mm, today the profiles are generally 70mm or more for the bay windows. If the depth of the rabbet is less than the thickness of the new frame, there are solutions to adapt.

How to take the dimensions for a renovation installation while maintaining the wooden frame

If you want to easily replace your wooden windows without having to do too much work, you can do a renovation installation. The new joinery is attached to the frame of the old wooden window. This is possible only if it is healthy, that is, there are no rotten areas. Do not hesitate to check by planting a screwdriver, if you notice that it is sinking in some places, you will not be able to fix the new window on it. You will then have to remove them, which is called a total removal.

For a renovation installation, the dimensions to be filled in are the dimensions of the back of the frame. The joinery is placed inside the existing frame. The internal dimensions of this frame are called the daylight dimensions and so that the new window can enter it without forcing it is necessary to deduce a set of pose. You must thus deduct 5mm in height, on the left and on the right.

For a renovation installation on an existing frame, you must select 3 dimensions :

• The height of daylight, to which you deduct 5mm ;
• The width of daylight, to which you deduct 10mm ;
• The lightening height in the case of an opening window, to determine the height of the handle.

Also note the thickness of the wooden frame in order to determine the suitable covering wings. They are fixed on the new profile and come to cover the wooden part that remains visible. They exist in several dimensions that can vary depending on the material (PVC or aluminum). For a PVC window, these cover wings are available in 40mm and 70mm.

Remember to raise the desired opening direction. The joinery will be manufactured to the exact dimensions that you specify.

How to take the dimensions for a flush installation on the wall

In a tunnel installation, the joinery is placed in the middle of the wall. But it is also possible to position it so that it is flush with the inner edge. It is then said that it is positioned in the inner nude. Some call it a flush tunnel installation, but this is a misnomer because in a tunnel a joinery always comes to rest in the middle of the wall. We should rather talk about laying in renovation on a flush wall, because it is a renovation profile that must be used.

In our online quote tool, for flush installation on the interior wall, you must therefore choose a renovation installation.

This type of installation is often used when we make a total removal, that is to say that the old wooden windows are dismantled, if there is a rabbet it is re-sealed. All around the carpentry, covering wings ensure a nice finish and hide the outline of the masonry which may have been slightly damaged during removal. Only the renovation profiles have covering wings.

For a flush installation on the wall, you must note the dimensions of the back of the frame. That is to say the dimensions of the opening to which you deduce a set of installation to install the window without forcing: 5mm in height, on the left and on the right.

So you have to raise 3 dimensions :

• The finished table height, to which you deduct 5mm ;
• The finished table width, to which you deduct 10mm ;
• The lightening height in the case of an opening window, to determine the height of the handle.

You also need to choose the size of the covering wings that will be placed all around. Unlike a renovation installation on a wooden frame in which you have to hide the old frame, there you can generally choose the smallest covering wings (typically 40mm PVC).

Remember to also note the desired opening direction. The joinery will be manufactured to the exact dimensions that you specify.

Are your measurements good?

We know that carpentry is a technical field that can seem complex. That’s why our technical service is here to help you if you have any doubts. Do not hesitate to call us!

Finally, all orders are checked before being put into production. We call you, and together we go over it again. For example, we will check how you took the dimensions, if you correctly deduced the pose sets. And quite simply, we check that everything you have ordered corresponds to your needs. Customer satisfaction is part of DISCOUNT JOINERY’s DNA.