We install extensions on interior doors. Accessories for interior doors What is included in accessories for interior doors

Installation of interior doors is a simple operation that can be performed even without such work experience. The frame for such structures is a door frame, which is attached directly to the wall. The dimensions of this product often do not exceed much the same parameters of the door leaf. But the thickness of the wall in most cases is much wider than this entire system. Additions to interior doors will help correct this difference.

Extensions are protective strips that are installed next to the door frame. They can often be found on entrance or interior doors. The latter option is more relevant, since the design decorates the surface, including the arrangement of high-quality slopes.

Technically, a door panel is an ordinary plank or board of a certain thickness and length. However, there is no universal standard that would regulate its technical characteristics. The structures are installed close to the frame, which eliminates the appearance of cracks and other unsightly openings. Today, additional products are often called factory-made products that are distinguished by their beautiful design and high-quality finish. Such products consist of several main parts:

Two vertical boards. Their length corresponds to the height of the doorway. They are attached directly to both sides of the frame. Fixation can occur using glue, self-tapping screws or other specialized methods.
Horizontal jumper. Structurally, it connects two vertical supports into a single integral system.

The width of all three of these elements is often equal. If the opening parameters are not standard, then each individual additional board is adjusted individually to the required dimensions.

Additional strips have several significant advantages:

Easy to install. Installation of extensions in most cases does not require the use of special fasteners.
Durability. The product fits tightly to the surface of the slope, preventing it from being destroyed by accidental physical influences.
Variety of styles. Extensions can be made to match almost any color or structure. Moreover, they are suitable for both wooden and plastic interior systems.

Why do you need a door opener?

Extensions are simple structures that are easy to build yourself.

These products are very practical and solve several main problems:

The main purpose of the extensions is to complement the door frame in order to decorate the opening. At the same time, the installation of such structures does not require special skills and abilities. Often the extensions are installed by specialists who also install the door. To create a unique system, the extensions can be complemented with various decorative inserts or carvings (wood).
Extensions exclude additional finishing of slopes. This saves specialists time and effort. It should be noted that the quality of the finish does not suffer in any way. In some cases, the resulting surface with the help of additional strips is more beautiful.

Additional insulation. A lot of cold air passes into the room through the gaps between the box and the wall. But this phenomenon is relevant only for entrance structures, while interior systems do not have this drawback.
Elimination of distortions and strengthening of the canvas. Some modifications allow you to visually align all the imperfections of the door frame. This is achieved by selecting different types of products that can even be attached directly to the door frame itself.

Interior door extensions are a completely independent design that does not have to be used in conjunction with a door frame. One of the directions is to arrange a kind of transition between several separate rooms. In this case, the use of doors is completely eliminated.

Types and forms

Door extensions are simple structures that are very difficult to divide into types. But still, there is a classification that takes into account the design features of the planks. Depending on these values, several types of additional products can be distinguished:

Standard. Externally, these extensions are ordinary slats of small thickness. Moreover, they do not have any additional structural elements that complicate the system. Interior extensions are often made from laminated slabs from waste wood. To give them an original design, their ends are finished with special edges. This also makes it possible to increase the material's resistance to moisture.
Telescopic. Products of this type are more versatile. A special feature of the telescopic extension is the presence of special grooves at the ends of the strip. Externally, they are very similar to the systems that are equipped with plastic or wooden lining. With the help of these grooves, extensions can be increased to almost any width. Therefore, such designs are much easier to adapt to different widths of the doorway.

The connection using a groove also eliminates the presence of gaps, whereas the use of conventional even strips leads to their appearance. If the frame of interior doors is made of wood, then a similar groove can be additionally cut into it. Thus, a high-quality connection is obtained, which is almost invisible from the outside.

Combined. Extensions of this type are a combination of a platband and a plank. These corner structures are universal and allow you to better cover the doorway. Such products are also supplemented with special grooves to simplify the installation procedure.

As for the shape of the extensions, it is not so diverse. The most popular and cheapest modifications are ordinary flat rectangular boards made of metal or plastic. But there are models that are complemented by decorative design. Today, column-shaped extensions are especially popular. They are made only from wood or its derivative materials. If the customer wishes, the manufacturer can supplement them with various decorative overlays or inserts. But the cost of such products is already much higher than classic modifications.

What sizes are there?

The extensions complement the door frame, so they must be adjusted to its dimensions. This is necessary to create a harmonious and practical system that will last for a long time without replacement. The modern market offers many standard sizes of additional trim strips, which allows you to adapt them to any opening dimensions:

Length. This value depends on the purpose of the specific element. For example, cross bars can have a length from 60 to 200 cm, depending on the type of door on which they are installed. As for the vertical slats, their height varies from 190 to 220 cm, depending on the modification. If you need to install extensions on non-standard doors, then upon request this value can be increased to 250-260 cm.

Width. This characteristic also varies over a wide range. Today, both wide and narrow modifications are available on the market. The width of the extensions often does not exceed 20 cm. Moreover, each manufacturer produces several standard sizes that differ in small increments. Thus, standard designs have a width of 10, 12, 15 and 20 cm. The parameters of telescopic extensions may also differ slightly - 90, 12 and 150 cm.
Thickness. This parameter is one of the most important, since the decorative appearance of the resulting system depends on it. The most common extension size on the market is 10 mm. Such products are very popular due to the fact that they fit many door frames. But the varieties of planks do not end there. The thickness of these products can vary from 6 to 30 mm depending on the material and type of manufacturer. Focus on the parameters of the door frame.

Materials

A special feature of interior doors is that they are made from materials that are distinguished by their practicality and unique decorative properties. Therefore, when making accessories, the same features are taken into account. It is important here that the products fit the main structures.

Today, the following materials are used to produce extensions for interior doors:

PVC. Plastic extensions are thin plates that resemble clapboard. They are distinguished by low strength and simple design. Therefore, they are used relatively rarely inside residential buildings. Sometimes they are used to complement plastic door frames to the balcony or bathroom. The advantage of this product is that it is not afraid of moisture.
Tree. Solid wood additional trims are the most expensive and high-quality products. The material is strong and durable, and its unique texture allows it to be combined with almost any interior style. Wooden structures are made from a variety of wood species. The most common are pine boards, as it is well processed and is available almost everywhere. But when choosing these components, it is also important to consider the material from which the door frame is made. Therefore, the best option would be to select from the same breed as the doors themselves. This will create a smooth transition of the pattern that will fit perfectly into the interior.

Chipboard and fibreboard. These substances are also very relevant for obtaining supplements. The material has a low price and relatively good strength. But over time, the slab can absorb moisture, which will cause it to swell.
MDF. Extensions made from it are distinguished by unique decorative parameters and relatively low cost. To give the material a unique design, it can be covered with various protective films (lamination and other options). These products also prevent moisture from penetrating inside, which extends the life of the product.

If metal doors are used as internal door structures, then their frame can be supplemented with extensions made from the same substance. But this combination is relatively rare. Moreover, the installation of these structures requires the formation of a special joining groove, which is not always technically possible.

How to choose an additional element?

After installing the door leaf, the question of finishing the slopes often arises. Today, this problem is very often solved with the help of extras. But, before you run to the store to buy these products, you should decide whether you need them. It is recommended to use such structures if the wall thickness is at least 13-15 cm. In this case, the box will take only 5-7 cm, and the rest will need to be sealed with additional boards.

When purchasing an additional strip, you should follow a few simple recommendations:

First of all, you need to decide on the dimensions of the board or timber for installation. To do this, measure the dimensions of the wall near the box to find out the height and width of the product. Please note that all measurements must be taken taking into account that the strip will be slightly hidden in the groove of the door frame.

It is advisable to take measurements in several places along the entire length of a particular side. This is important, since openings often do not represent an even geometric figure, which does not allow using only one value when choosing. If you have calculated the dimensions of the extensions, then it is advisable to add a few more centimeters of reserve to these values.

The next step is to select a strip for a specific type of door leaf. This often takes into account the material from which the doors are made and their type. So, for example, the same platbands as for classic single-leaf modifications will not be suitable for a pencil case door. The style of the extensions is selected individually, taking into account the personal preferences of the buyer and his financial capabilities.
Manufacturer. This characteristic is also one of the most important, as it affects the quality of the material. Today, many companies produce accessories, but not all of their products can serve long and reliably. Among all this diversity, brands such as Mario Rioli, Matadoor and many others should be highlighted. At the same time, be sure to take into account customer reviews about each of them in order to purchase quality products.

What can be replaced?

You can make an additional strip for interior doors yourself. The main thing here is to choose a material that matches the color of the main style of the door leaf and frame.

You can replace factory accessories with several materials:

Plywood. Both regular and moisture-resistant types of substances are suitable for this. The variety of products allows you to choose not only the thickness, but also some decorative features of the material. After making plywood boards, they must be coated with protective varnishes or paints to prevent delamination.
Wooden plank. Often the additional product is this type of product. To obtain a high-quality plank, the board is carefully sanded and varnished. If you have a router, you can cut out several decorative elements on its surface.
Plastic lining. The best option for making accessories. The products are low in cost and cut perfectly, which will allow you to cut planks of the desired size.
Laminate. This material is also available in the form of slats that are easy to attach to the wall. But they are rarely used intentionally, as they are expensive. You can build extensions from the remnants of the laminate after laying it on the floor.

In this article I will tell you in what cases it is necessary to install extensions on interior doors and how to determine the width of the required extension.

What is dobor?

Installation of additional boards (additional boards) is required when the wall thickness is greater than the width of the door frame. Typically the box width is 7-8 cm.

Dobor- this is an element that connects to the door frame, thereby increasing the width of the frame to the thickness of the wall. Installation of extensions is necessary even if the wall is 5 mm thicker than the frame. The exception is telescopic door frames, where the platband is inserted into a groove. This system allows you to slightly increase the width of the box, but no more than 10-15mm. If the door frame has a groove for installing a platband and is equipped with telescopic platbands, then the door frame must also have a groove for installing a platband.

How to determine the width of the required extension?

You can determine this yourself. To do this you need:

Measure the width of the new interior door frame
Measure the wall thickness of the doorway, preferably in several places, for example at the bottom, top and center of the doorway
Subtract the width of the box from the wall thickness
We get the width of the required addition

The wall thickness is 8 cm, but the width of the box is even smaller. Addition is needed If the wall has different thicknesses in different places, it is worth consider only the maximum value. As a rule, manufacturers of interior doors produce extensions in several sizes. If the required extension size does not match the one available for sale, it is worth buying a wider extension. When installing an interior door, the extension is adjusted in size to the nearest millimeter. This includes adjusting it to size.

note that extras are usually calculated with a small margin. 2 cm in reserve for cutting the extension and for possible deviations of the walls is quite enough.

Have you bought a door to install in an interior opening, but didn’t get the right size? The article will tell you what an extension strip is, how to choose it correctly and install it without the help of specialists, with your own hands. In addition - a video, as well as instructions with photos.

What is a supplement and why is it needed?

Many doors produced by factories are designed for standard city apartments. Installation difficulties usually arise in old buildings or country houses. The thickness of the walls in these rooms may differ from the standard one, which is usually 7-8 cm. The places in the opening that remain unblocked by the door frame are often finished with plastic, plasterboard or plaster. However, a much more convenient way out of the situation is to install a kind of expander - an extension.

This element consists of 3 strips - 2 vertical and 1 horizontal. With their help, it is quite easy to enlarge the area that covers the door frame - i.e. “get” the required centimeters. The part you need can be purchased along with the entire structure or separately. If you have the necessary tools and materials, make the additional strips yourself.

Advice. One of the main criteria for selecting a product is its similarity with other details of the interior design. To make the addition look organic and not stand out from the general background, carefully select it, focusing on the color and texture of the door and frame.

It is difficult to highlight the pros or cons of this part - this is just one of the possible options that allows you to fill the width of the box. Those who chose this method note the following features of the extras:

due to its use, you can install the door quite quickly;
using a strip allows you to avoid wet finishing of the door, which is not very beneficial for wood (using wallpaper or plaster);
thanks to this detail, the stability of the entire structure increases;
an interior door with an installed extension looks much more attractive and has a finished, presentable appearance.

Attention! In cases where the door jamb is severely skewed, and the door leaf was adjusted to fit the deformed frame, additional adjustment will not help. First you need to redo the structure itself.

Types of additional strips for interior doors

Regular. They look like simple slats, pre-laminated and then covered with veneer. They differ in type and color of decoration. The width of such an extension can be 10, 11, 15 or 20 cm.

Telescopic. Another name is typesetting. With their help, it is possible to expand the opening in almost any wall; they have a width of 9, 12 and 15 cm. These extensions are similar to a carriage rail: on one side they have a ridge, and on the other - a groove, with which they are easily attached to doors without nails. For installation, just one glue is enough.

Attention! Telescopic extensions are more expensive than regular ones, but they receive a lot of positive reviews.

Combined. They perform the functional tasks of the platband and regular extensions, and look like a decorative corner. Such products are mounted on a door frame, at the ends of which there are deep recesses. You need to insert extra into them.

Attention! Combined extensions are designed to expand the box within 2-5 cm and are only suitable for walls of small thickness.

How to choose an accessory: material, sizes

Often, for the manufacture of extensions, edged or tongue-and-groove boards are used, which have a groove for better and more convenient installation. In addition to wood, additional planks are made from veneer, MDF, chipboard, plastic, laminate. If the width of the wall is too large, it is better to opt for waterproof plywood. It is also recommended to install it in rooms with high humidity, for example, in the bathroom.

Extensions come with or without edges. In the first case, the end of the plank has the same coating as the entire part. Most often these are products in the production of which laminate, laminate, and PVC are involved. Veneered products are mainly produced without edges. The thin section of wood, called veneer, is brittle and inelastic. Therefore, it is almost impossible to bend it at an angle of 90° without breaking it.

Please note that the additional profile used in glazed loggias is not suitable for the door. Factory products have standard dimensions:

height – 2 m;
thickness – 0.5-2 cm;
width – 7-40 cm.

A part whose thickness is at least 1 cm is considered especially high quality. As for the width, 10 cm is usually enough. Even if you take several of these planks, it will not be difficult to install them by joining each other, and the finished structure looks aesthetically pleasing and neat. A profile with a large width is most often used not for interior doors, but for entrance doors.

Before buying an additional plank, take all measurements: by inviting a specialist or yourself. It is worth determining the dimensions after the main structure has already been installed. The width of the extension you need is the figure obtained after subtracting the width of the box from the wall thickness. It is better to add 1-2 cm to the result obtained so as not to make a mistake. Since the walls in many houses and apartments are often not perfectly smooth, measure the thickness of the opening in at least 4 places. Focus on the maximum indicator.

Advice. To furnish a country house, you can purchase a door with a frame that has a blank for additional installation of the extension - a grooved quarter.

Do-it-yourself addition and installation. Instructions

Stages of installation of a conventional additional strip:

Install the main interior structure in the doorway and wait until the foam dries.
If the box has a special recess for collecting, clean it thoroughly. If there is no such recess, free up space behind the door frame. The width of this area should be 1.5-2 cm, depth - 1-2 cm.
Start installing the extension by cutting the top strip. First, adjust its size in length (even if it protrudes slightly beyond the boundaries of the box), and then in width. To do this, insert the extension into place, but inside out. Using the wall as a guide, place 2 marks. Pull out the strip, connect the marked points with a line and cut with an electric jigsaw.
Cut the side strips in the same way. Pay special attention to their length: there should not be a single gap between all the slats. The top panel should be in a strictly horizontal position on the side slats (you can use a level to check). Once you are sure that this is the case, proceed to fasten the product.
To prevent gaps, wedge the panel between the frame and the doorway. For this, use wooden wedges, dried and compressed foam, or cardboard folded several times.
Check how the horizontal and vertical planks fit together and how evenly they are installed. Pay special attention to the lower segment of the side panels.
Secure the width strips on both sides along the width. After the foam has hardened, fill the remaining space. When the mixture has completely dried, begin installing the platbands.

Stages of installation of a telescopic extension almost the same. The difference lies in how the individual planks are connected to each other using the extension method.

The first rail should be installed in the doorway first.
Having secured it securely, fasten the second row.

Experts warn that it is impossible to install a completely assembled structure: there is a high probability that the connection of the plates will be broken. This mainly applies to sets of 3 strips and more. You can handle two telescopic rails by installing them at the same time. However, this requires considerable experience and a large number of spacers.

Installation of combined accessories quite simple because they do not need to be strengthened additionally. The sequence of actions is as follows:

Insert the strips into the grooves of the door frame.
Carefully adjust the corners - first of all on the horizontal trim, and then on the side ones, but only from the bottom side. If you do this at the top, you can damage the special groove that ensures a tight connection between the side planks and the horizontal one.

Advice. Recommendations for the separate installation of first the box and then the planks are relevant for narrow extensions. If you do not have sufficient skills for such work or are installing a wide strip, first assemble the box, attach the extension to it, and then place the entire structure in the doorway.

To attach additional slats to the interior door frame, you can use liquid nails or self-tapping screws. If you are connecting these parts from the outside, select plugs for the screw heads that match the tone of the entire structure. A correctly installed extension does not limit the opening angle of the door, and the interior design looks neat.

How to install extensions correctly: video

The door frame and the opening in the wall do not always match in size. In such a situation, correct installation of the doors is ensured by the use of an additional strip. Installing extensions on interior doors adds completeness to the design of the structure and protects the wall opening from mechanical influences.

The need to install additional elements

What is an extension for an interior door? This is a special horizontal or vertical strip (extender) that covers the end wall of the doorway between the platband and the frame (tray). Door structures are produced in standard sizes, which sometimes do not correspond to the thickness of the walls in private houses and apartments.

Additional elements perform two main functions:

Aesthetic - they cover defects on slopes and add beauty to the door structure.
Protective - strengthen the door frame, preventing it from loosening and distortion during frequent use.

Raw materials for making accessories

Taking into account the material, color, texture, texture and other characteristics of the door leaf and frame, an additional panel is selected. It is recommended to purchase expanders at the same time as the door and from the same manufacturer. The raw materials for their production are:

array of coniferous trees;
Chipboard, fibreboard, MDF;
plastic.

Panels made of any material are covered with a top decorative layer. Finish options:

natural veneer;
lamination (coating of paper impregnated with melamine resins);
films made of polymers (PVC, eco-veneer and others);
varnish coating (for wood);
painting.

Lightweight and durable extensions are made from thin MDF sheets mounted on a wooden frame and with a cellular internal filling. It is possible to make expansion panels for interior doors with your own hands. The difficulty will be choosing the shade and texture of the panel coating. Such extensions for interior doors look original if they have a contrasting color, differ in texture from the entire structure, or are decorated with decorative carvings.

Types of additional strips

Standard straight retractors are available with or without a protective edge. Ordinary flat panels that are attached to the wall with nails or glue. It is recommended to use planks with an edge, since a butt-mounted platband may not hide the entire thickness of the material and worsen the appearance of the passage. The convenience lies in the fact that such an extension for an interior door can be adjusted in width on site during installation.
Telescopic extensions for interior doors are distinguished by the presence of longitudinal grooves on both sides, which ensure tight, reliable adhesion to the platband and door frame of a similar configuration without additional fasteners using the “tenon-to-groove” principle. The width of the expander is adjusted by extending the bar from the slot by 2-7 mm. Unlike straight ones, telescopic slats are easier to install and look more attractive.

Dimensions of extensions for interior doors

The dimensions of the additional strips are determined by the size of the door openings. In height they are produced in the range of 206-220 cm. Thickness depends on the material of manufacture and ranges from 5 mm to 40 mm. In width you can find extenders from 50 mm to 56 cm. When the opening depth is more than 20 cm, experienced designers recommend decorating the door with slopes. Such extensions for interior doors that are wider than 15 cm are not in demand and are usually made to order from the buyer.

The net width of the panel is determined by measuring the depth of the doorway and subtracting the width of the frame from this number. It is extremely rare that there is a need to install a door in the middle of the jamb. In such a situation, the result obtained is divided in half, and expansion strips are fixed on both sides of the box.

Methods for installing accessories and preparatory work

It is more convenient and easier to install expansion strips simultaneously with the door structure. Extensions are installed in two ways:

Having conveniently positioned the door frame in an open space, resting against a wall or horizontally, the expansion panels are fastened to the frame and installed in the opening as a solid structure. If there are no grooves, the parts are connected with glue, screws or bolts. The geometric correctness of the angles is checked using diagonals or a level. Then the gaps between the extensions and the wall are foamed.
The door frame is installed. After the foam has dried, the extensions are attached to it.

When installing expansion panels, it is important that all connecting surfaces are clean. Before installing the extensions on the interior door, excess foam is cut off on the fixed frame, the grooves and parts are cleaned of dust and other contaminants. This measure will prevent the door structure from skewing. To fix the expanders, it is recommended to use polyurethane foam with low drying pressure.

Installation of simple additional strips with self-tapping screws

Standard straight extensions are installed simultaneously with the door or after its installation in the following sequence:

The width of the horizontal panel is determined, and if there is excess, it is cut off.
The plank is tried on again and, if all dimensions match, it is fixed with self-tapping screws.
The side parts are adjusted and screwed to the wall in the same way.
All joints are sealed. Platbands are put on.

The screw caps are closed with furniture plugs (self-adhesive or plastic) in the color of the facing material.

Features of installing telescopic extensions

Installation of telescopic panels is easier and faster. The wall and the installed tray are pre-cleaned. The planks are tried on and the excess length is cut off. The upper horizontal element is mounted first, then the sidewalls. Extensions of this type are inserted into the grooves of the door frame to the required depth. That is, until the panel covers the entire open surface of the wall. For a strong connection, the end of the expander is tapped with a rubber mallet. The panel is attached to the wall with liquid nails. A level is used to check the evenness of surfaces and install platbands.

Design of portals

Today, more and more often, designers propose combining different living spaces with original portals. Openings without doors expand the space and create a special microclimate in the house. The design of passages in a single stylistic solution with the rooms favorably emphasizes the unique design. Standard rectangular doorways are decorated with extensions for interior doors and trims.

In a country house, portals form the passages to the terrace or to a room with a fireplace. The apartments have original looking portals that open onto an insulated loggia or combine the kitchen space with the living room.

Some recommendations will help you implement the correct installation of interior doors with your own hands:

Straight extensions are attached to a perfectly flat wall with liquid nails. The surface is degreased, the adhesive is applied pointwise, the panel is pressed and gently tapped with a rubber hammer.
For any installation method, it is recommended to immediately put on the trims, as they level the extensions and are additionally fixed with foam.
When there is significant curvature of the walls or a wide installation gap, backing bars are used.
When the door is opened 180°, the expanders are installed on the side opposite the hinges.
An electric jigsaw is used to cut additional panels.
Small cracks are filled with wood putty to match the facing material.
For installation, black or hardened screws are used.
Do-it-yourself installation of interior doors will be easier if a wooden plank is attached to unplastered slopes.
When adjusting the dimensions at the installation site, the parts are applied to the wall with the back side and notes are made with a pencil. The cut strip is again tried on in its place and only after that is fixed. Vertical panels may vary in size!
The horizontal expansion bar is leveled using wedges.
Spacer bars installed in several places (for example, made of foam plastic) will help to avoid distortion of the panels when the foam dries.

Additional strips enhance the doorway, logically completing its decoration. It is quite possible to decorate the wall yourself, since the long and labor-intensive process of installing expanders does not require special skills or the use of complex equipment.

An interior door separates one room from another and is part of the interior, so it should have a beautiful appearance. How beautifully the doorway is designed creates an impression of the room, since it is the first thing that catches the eye of the person entering. Since the thickness of the wall is usually much greater than the width of the frame, after installing the door there remains a part of the opening that needs to be hidden. For these purposes, special decorative elements are used - extensions.

What is an accessory for interior doors?

In most cases, the thickness of the wall is greater than the width of the door frame. More recently, when replacing a frame, it was necessary to carry out construction work in order to somehow improve the uncovered part of the opening. First, the slopes were plastered, after which they were primed, painted or wallpapered. Such work requires certain skills and takes a lot of time. Nowadays, to close the slopes of interior doors, extensions are most often used.

An extension is a decorative strip up to 10 mm thick and about 2 m long, which on one side has the same finish as the installed door. The width of the extension is selected in each case separately depending on the size of the door frame. Installation of this element takes little time; any home craftsman can do it. After installing the extensions, the doorway takes on a beautiful finished look and fits harmoniously into the interior of the room.

Additions allow you to give the doorway a beautiful and finished look

The door frame must meet several parameters:

be made of the same material as the doors;
match the door in color;
have the required width.

In addition to the fact that additional strips serve an aesthetic role, hiding defects in slopes, they also help strengthen the door frame.

Typically, extensions are made from the following materials:

natural board;
laminated chipboard;
plywood.

A large selection of colors and shades allows you to choose extensions that match the door frame so that the entire structure looks like a single whole.

Types and types of additional elements

Although the type of construction of the extensions is not very diverse, before purchasing you need to familiarize yourself with their types and features:

Regular. These are simply slats made of MDF, chipboard or laminate. Eco-veneer is most often used as a covering; a decorative edge is usually made at the end, although untreated planks are also found. If your trim does not have an edge film, you can glue it on yourself using an iron. It is better to do this, because the edge will help hide surface defects and protect the material from moisture so that it does not swell. The standard length of the additional strip is 200–220 cm, and the width is 100, 150 or 200 mm. Experts recommend buying products with a thickness of at least 10 mm. The main advantage of conventional additions is their low cost.
A regular trim is a decorative strip of specified sizes
Telescopic. Such elements are similar to lining in the method of fastening, that is, they have grooves for fastening to each other and with platbands. They can have different colors, differ in the finishing method and are made from the same materials as regular extensions.
Using a telescopic extension, you can close slopes of any width
Combined. They combine the extension and the casing. The combined extension is a corner that is installed in special grooves in the door frame. The disadvantage of this solution is that it is impossible to close wide partitions with them. But if after installing the door there is 2–5 cm of unclosed space left, then combined extensions are the best option.
Combined elements combine platband and extension

The height of the trim corresponds to the size of the door and is usually 200–220 cm. The thickness of the strip should be such that it fits tightly into the groove of the door frame. Typically the groove size is 10 mm, so the additional elements are made the same. Since the thickness of the walls can be different, extensions are produced with a width of 30 to 200 mm or more.

The additional strip can have a width from 30 to 200 mm and even more

If in apartments doorways and wall thicknesses have standard values, then in private houses this is not always the case. Ready-made additions are often not suitable here, so if the doors and frames are made to order, then they must be immediately equipped with appropriate decorative strips. If this is not possible, then you can simply dock several additional elements with each other. To obtain the desired width of the plank, it can be cut with a regular hacksaw. When joining several extensions on the front side, be sure to leave a groove into which the platband can then be inserted.

How to do the calculation correctly

In order to purchase extras of the required sizes, you first need to calculate them correctly. This is not difficult to do, so you can do everything yourself:

Calculation example: wall width is 250 mm. You purchased a box 70 mm thick, which means you need an extension 180 mm wide. Since the nearest standard size is 200 mm, it is necessary to purchase just such extras. The excess width is sawed off with a hacksaw.

When installing a stacked or telescopic extension, select the width of the slats to obtain the required size.

Installation of extensions for interior doors

Before proceeding with the installation of the extensions, it is necessary to carry out preparatory work. All dirt and excess foam are removed from the opening so that they do not interfere with installation.

To work you will need:

Before you begin installing the extensions, you need to secure the door block well.

Installation of conventional extensions

Installation procedure for simple extensions:

Cut out the material. Using a jigsaw or hand saw, cut the strips to the required length and width.
Extensions can be cut with either a regular hacksaw or a power tool
The groove in the box is cleared of debris, otherwise you will not be able to install the accessories correctly.
First, insert the top bar, carefully level it and fill the gap with foam.
The top strip is installed first
The side strips are fixed in a similar way.
The side strips are mounted after installing the top element

Often, ordinary extensions are fixed using self-tapping screws. To do this, holes are made in the canvas, after which it is screwed to the wall. This work is easier to do if the opening is framed with wooden blocks. After installing the screws, select plugs to match the extensions and cover the heads of the screws with them.

Installation of telescopic elements

The process of installing telescopic extensions is not very different from the previous version. If you need to close a wide partition and the width of one extension is not enough, then you need to connect several planks. Some craftsmen first connect the planks to obtain the required width, and only then install them. If you are doing this for the first time, it is better to first fix one bar, and after the foam hardens, the other. Although the work will take a little longer, since drying the foam when fastening each element takes time, the result will be more accurate and of higher quality.

The groove in the telescopic extension allows you to adjust its width

Installation order:

Video: connecting telescopic extensions

Installation of combined accessories

The easiest way to sew up slopes is with the help of combined extensions. For their fastening it is not necessary to use polyurethane foam.

The work is performed in the following order:

If you do not have experience in performing such work, then finishing one doorway with combined additions will take no more than 30 minutes, and professionals can handle it in 15 minutes. But although the process of installing combined accessories is simple, everything must be done carefully and efficiently. If the extensions are installed incorrectly, even the most expensive interior doors will have an unattractive appearance.

Incorrectly installed fittings can ruin the appearance of even the most expensive door, so the work must be done carefully and responsibly

Non-standard situations

Very often there are situations when the doorway has significant deviations from the horizontal and vertical.

Extension of the doorway to the outer edge. You can’t bend the board, as it will start to break, but you need to hide the slope. In this case, creating a frame from wooden blocks, plywood and drywall will help. This creates an additional flat wall, which is then covered with an extension.
The box is skewed vertically or horizontally. In this case, you can trim the additional elements to the existing dimensions, but you won’t be able to get a beautiful result. It is better to dismantle the door frame and install it correctly.
The walls have a slope. If it is no more than 5 mm, then it can be corrected using plaster applied under the platband. In other cases, wedges must be used.

How to eliminate gaps after installing extensions

After the additional elements have been installed, the resulting gaps are eliminated using polyurethane foam. It must be remembered that when the foam hardens, it expands and can bend the door frame and extensions. To prevent this from happening, the following recommendations must be followed: