How to correctly size a door opening? Practical guide

Accurate measurement of the door opening is crucial for the correct installation process. Although many people do the door installation themselves, it is increasingly common to choose the help of professionals to avoid costly mistakes. Is this really necessary? It's worth knowing the basic rules for determining the dimensions of the wall opening to match the most common internal door sizes. Find out what kind of opening to prepare for an ‘80’ wide door, and what dimensions will be suitable for ‘60’, ‘70’ and ‘90’ models.

Before you decide to buy a new door leaf, it is worth first comparing the dimensions of the door frame, the arrangement of the hinges and the shape of the rebates in the existing door with the parameters of the selected model presented in the showroom. However, in the case of the installation of the entire set, i.e. the leaf with the frame, many manufacturers recommend using the services of professionals, which allows you to avoid problems and guarantees a precise fit of all elements.

How to correctly determine the dimensions of an interior door opening?

In order to avoid later complications and additional costs, it is advisable to determine the size of the door opening for an ‘80’, ‘90’ or other width sash well in advance, preferably before the final finishing of the walls. This is also a good time to decide whether you want to install a fixed or an adjustable frame, as the exact dimensions of the opening also depend on this.

Remember that the opening in the wall must always be slightly larger than the door leaf itself. Exactly how much? This depends on both the type of frame and the thickness of the wall. It's easiest to plan this during the construction phase of a house or flat - then you can immediately prepare the openings to suit the door model of your choice. However, things can vary when renovating. Sometimes an existing opening needs to be widened, other times it needs to be narrowed by adding a section of wall. In both cases, precise measurements are essential, allowing for a few centimetres of space for the frame, which ensures the stability and proper functioning of the door after installation.

What dimensions should I prepare for the door? Frame type

When planning the installation of an internal door with a standard width of ‘80’, it is crucial to take into account the differences resulting from the choice of frame type - fixed or adjustable, rebated or non-rebated. Each of these variants requires slightly different dimensions for the door opening.

What size of opening for an 80 mm door with a fixed frame?

When opting for a traditional fixed frame, the opening in the wall should be about 20-30 mm wider than the door set itself. The width of an ‘80’ door on the outer side of the frame is usually 89 cm, which means that the appropriate width of the installation opening is 91.5 cm. The height of the opening in this case should be 207.5 cm.

Summary for POL-SKONE fixed door frame:
- Hole width: 91 cm
- Hole height: 207.5 cm

Summary for DUO fixed frame without rebate:
- Opening width: 92 cm
- Hole height: 208 cm

Opening for door 80 with adjustable frame

If we choose an adjustable frame, the required opening will be slightly narrower. For an ‘80’ door, an opening width of 87.5 cm and a height of 205.5 cm is recommended.

Summary for DIN adjustable frame, DIN SOLID, DIN AQUA:
- Opening width: 87.5 cm
- Hole height: 205.5 cm

Summary for DIN DUO, DIN SOLID DUO, DIN DUO AQUA adjustable frame without rebate:
- Opening width: 89 cm
- Opening height: 205.5 cm

Summary for VERTIGO adjustable frame without rebate:
- Opening width: 89 cm
- Hole height: 206 cm

Summary for REVES reverse rebated frame:
- Opening width: 90.5 cm
- Hole height: 208.5 cm

Why does precision matter?

Correct matching of the opening to the type of frame significantly facilitates installation and ensures the stability of the entire structure. An opening that is too small can make installation difficult, while one that is too large will require additional filling with installation foam and adjustment, which generates unnecessary costs.Planning to install door 80? Keep these dimensions in mind to avoid surprises at the installation stage!

What dimensions of the opening for the other doors 60, door 70, door 90 will be suitable?

Choosing the correct door opening dimensions is the key to a smooth door installation and an aesthetically pleasing end result. The openings for the popular door leaf widths ‘60’, ‘70’ and ‘90’ also need to be matched to the selected type of frame - fixed or adjustable.

What type of door opening for a ‘70’ door with a fixed frame

The width of a ‘70’ door on the outer side of the frame is usually 79 cm, which means that the appropriate width of the installation opening is 81.5 cm. The height of the opening in this case should be 207.5 cm.

Summary for POL-SKONE fixed door frame:
- Hole width: 81.5 cm
- Hole height: 207.5 cm

Summary for DUO fixed frame without rebate:
- Opening width: 82 cm
- Hole height: 208 cm

Opening for door 70 with adjustable frame

If an adjustable frame is chosen, the required opening will be slightly narrower. For a ‘70’ door, a 77.5 cm wide and 205.5 cm high opening is recommended.

Summary for DIN adjustable frame, DIN SOLID, DIN AQUA:
- Hole width: 77.5 cm
- Hole height: 205.5 cm

Summary for DIN DUO, DIN SOLID DUO, DIN DUO AQUA adjustable frame without rebate:
- Opening width: 79 cm
- Opening height: 205.5 cm

Summary for VERTIGO adjustable frame without rebate:
- Opening width: 79 cm
- Hole height: 206 cm

Summary for REVES reverse rebated frame:
- Opening width: 80.5 cm
- Hole height: 208.5 cm

How to measure a door opening?

Precise measurements are the basis for a successful installation. It is worth remembering that the measurements should be checked in several places, as walls are rarely perfectly even.

Here are some practical tips:

• Height of the opening - measure from the floor to the lintel at at least two points: left and right, and preferably additionally in the middle.
• Width of the opening - measure at several levels (e.g. at the floor, in the middle and at the top), taking into account the smallest result.
• Wall thickness - measure it on both sides of the opening at three points and also take the smallest measurement.

These measurements will help you avoid surprises during installation and ensure that your chosen door will fit perfectly.

What type of opening for a 90 mm door with a fixed frame

The width of a ‘90’ door on the outer side of the frame is usually 99 cm, which means that the appropriate width of the mounting hole is 101.5 cm. The height of the opening in this case should be 207.5 cm.

Summary for POL-SKONE fixed door frame:
- Hole width: 101.5 cm
- Hole height: 207.5 cm

Summary for DUO fixed frame without rebate:
- Opening width: 102 cm
- Hole height: 208 cm

Hole for 90° door with adjustable frame

If we choose an adjustable frame, the required opening will be slightly narrower. For a ‘90’ door, a 107.5 cm wide and 205.5 cm high opening is recommended.

Summary for DIN adjustable frame, DIN SOLID, DIN AQUA:
- Hole width: 107.5 cm
- Hole height: 205.5 cm

Summary for DIN DUO, DIN SOLID DUO, DIN DUO AQUA adjustable frame without rebate:
- Opening width: 109 cm
- Opening height: 205.5 cm

Summary for VERTIGO adjustable frame without rebate:
- Opening width: 109 cm
- Hole height: 206 cm

Summary for REVES reverse rebated frame:
- Opening width: 110.5 cm
- Hole height: 208.5 cm

Doors ‘60’, ‘70’, ‘80’, ‘90’ or ‘100’? Where are they most often used?

The choice of door width should be adapted to the function of the room. Here are the most common solutions:

• 70 and ‘60’ doors - mainly used in utility rooms, pantries, dressing rooms and as an entrance to small toilets.
• 80 and ‘90’ doors - this is the standard for bedrooms, living rooms, kitchens or bathrooms. These sizes also meet building regulations for minimum door widths in utility rooms.
• ‘100’ doors - increasingly chosen for modern flats, open living areas and wide corridors.

In older buildings you can still find narrower doors, such as ‘60’ or ‘70’, which were once common in rooms. They are still available on the market, allowing you to fit a new door leaf into an existing door frame without having to widen the opening.

The most common mistakes when measuring doorways

An accurate measurement of the door opening in the wall is essential to avoid problems during installation. Even a small mistake can result in a door that does not fit. What are the most common mistakes?

1. Door opening too large

If the opening is larger than required, the situation is relatively simple to rectify. It can easily be narrowed by filling the missing space with mortar or plasterboard. It is important to carry out the work carefully, ensuring the stability of the substrate for the frame. An installation hole that is too large will require more foam to be applied, which unfortunately works and can affect the performance of the door itself.

2. hole too small or too narrow

This is where things get complicated. We can try widening the opening, but this involves additional work, noise and dust. Alternatively, we can replace the door with a smaller one - provided the model was not a bespoke product. Standard sashes are often returnable, but only if the packaging is intact and the time since purchase has not been too long.

3. inaccurate measurements

The most common cause of problems is inaccurate measurements. It is a good idea to check the opening in several places - both in terms of width and height - to ensure that the walls are even. The thickness of the wall should also be measured at several points and the smallest value should be used for further calculations.

Installing the frame - better by yourself or with a professional?

Although more and more manufacturers are providing instructional videos to make it easier to install doors yourself, it is worth considering using a professional. Professional installation means:

• Certainty that the door will be properly fitted.
• Warranty protection - in many cases longer if an authorised specialist installs the door.
• Saving time and avoiding possible corrections.

If you opt for an installation service, you can often count on a better price for the whole set - the door including installation.

Bottom line - why does precise measurement matter?

Regardless of whether you choose an 80 or 90 cm door, or the more unusual 100 or 220 cm door, a properly prepared door opening is the basis for a successful installation. Accurate measurements avoid stress, additional costs and delays in finishing work. If in doubt - it's worth consulting an advisor in the showroom.

Before ordering a door - measure everything twice!