The filling of the door leaf is its basis, the skeleton, which is directly involved in imparting a number of properties to the finished product, including: rigidity and durability of the structure, sound insulation, fire resistance, etc. One of the budget options for internal door filling is honeycomb filling, pressed cardboard that fills the void inside the door. Honeycomb is an ideal filler in terms of lightness and price. Thanks to the cellular “honeycomb” structure of the door leaf, the weight of the door is effectively reduced. As a result, the load on the hinges is reduced, and thus it is possible to avoid door sagging during the period of its operation. The average weight of doors with honeycomb filling in a solid design is a maximum of 17 kg. It is because of this that “cellular” doors have another name - lightweight doors (also used are interior construction doors, economy class interior doors, “dummies”). Honeycomb began to be actively used for interior doors in the middle of the last century, and today such filling of the internal space of the door is one of the most common.
Honeycomb is used as the most economical option in inexpensive veneered or laminated doors. The strength of such doors, of course, is inferior to the strength of solid ones. Hollow filling is unacceptable for use in doors with increased requirements for operational load. They are not recommended to be used as input. But indoors (offices, apartments, etc.) is an acceptable option. It is appropriate to use them as temporary doors for completing construction projects, the so-called interior construction doors. The cladding of “honeycomb” doors is carried out with MDF panels, which are then laminated or veneered. Just like solid and semi-solid doors, doors with honeycomb filling can be smooth or paneled, solid or under glass, left- or right-handed, with or without a rebate, etc.
Door block design
The door frame with honeycomb filling is made of coniferous wood of furniture humidity (8 ± 2%), glued bars with different directions of fibers through a microtenon (a method of adhesive joining of parts when longitudinally merging wood fragments into an array). This is done in order to relieve stress in the wood and prevent bending of the door leaf (the stacked structure is less susceptible to deformation when temperature and humidity change). The width of the frame bars must be no less than single, one and a half thickness of the leaf (the thickness of the lightweight interior door leaf is usually no more than 40 mm), but not more than 60 mm. The frame of canvases with a width of 900 mm or more, as well as a height of more than 2000 mm (non-standard) must have additional vertical bars on both sides. Unglazed (solid) panels are made with only one outer frame. Glazed doors also have an internal frame that matches the size of the glass being inserted. Where the lock is located, the longitudinal parts of the frame must be increased in width due to the additional installation of bars.
Inside the lightweight door leaf there is a paper-honeycomb core (attached to the frame with staples). The main function of the honeycomb is to fill the void between the skins and give rigidity to the sheet, eliminating local deflections of the skins on both sides of the sheet, while creating flatness of the surfaces. Honeycombs, depending on the cell size and cardboard density, vary in rigidity. For doors, honeycombs with a cell size of 35 - 45 mm and a compressive strength along the thickness in the stretched state of at least 0.5 kg/cm2 are mainly used. According to the experience of honeycomb core manufacturers, it is preferable to use honeycombs with a cell size of 35 mm or less for doors.
Two sheets of HDF (sheet thickness 4 mm) or MDF (6 mm) are glued onto the frame on both sides in a hot press, resulting in a single durable structure that is resistant to mechanical stress and changes in temperature and humidity. The “pie” made in this way is laminated with various finishing films or veneers of various species. Based on such canvases, simple smooth or more complex paneled versions of doors are made. The vertical ends of the canvas are finished with a PVC edge, which, unlike conventional melamine (paper) edges, has high strength and elasticity and does not peel off or break during use. After gluing, sharp corners of the edge are cut and ground on a machine, which eliminates the possibility of scuffing and peeling.
It should be added that MDF interior doors can be made with a rebate (“quarter”, rebate) or without it. These terms refer to the design of the ends of the door leaf, in which part of it covers (covers) part of the door frame. Sketches will help you understand the definition, one of which shows a door with a vestibule, the other without it.
Very often the vestibule is called a “quarter”, since the thickness of the vestibule is equal to a quarter of the thickness of the door leaf. And since the milling cutter, making a rebate, cuts a rebate in the wood, another name was generated - doors with a rebate. Thus, a door with a quarter, a door with a rebate and a door with a rebate are three synonymous terms that mean one constructive solution, colloquially used in most cases in relation to interior doors. When complete with a corresponding door frame, such a door when closed has no visible gaps between the frame and the door leaf. A quarter ledge provides increased thermal insulation and sound insulation, and also hides inaccuracies in the installation of the door frame. It should be noted that the cost of an MDF interior door with a “quarter” is usually higher than its counterpart without a rebate. An integral component of any MDF interior door is moldings. Door moldings are several types of components: door frames, trims, extensions, strips and thresholds. They are selected in such a way as to match the material and style of the door leaf. It should be said that for lightweight interior doors, the simplest and therefore most affordable options for molded products are used.
A door frame is an element of a door block for hanging a door leaf, which is fixedly fixed in the doorway. The basis for the door frame is dry lumber (moisture content - no more than 8±2%) and MDF. Box lumber is made from dry lumber using the end-joint method. Glued blanks are profiled to a given size. MDF is cut to a given size at a cutting center. The MDF strip is glued with hot melt adhesive on an automatic line for veneering molded products. The resulting “rough blank” is processed on four-sided planing machines, after which it is lined with finishing films or veneer.
Extension is a universal expansion element. Used for decorating different depths of doorways, made of MDF. The extensions are mounted in such a way as to fill the gap between the platband and the frame. After installing the extensions, plastering of the slopes is no longer necessary, which significantly reduces the cost of the installation process. The facings of the extensions are selected in such a way as to match the style (texture, color) of the entire structure.
Platband - profile decorative strips used to frame the doorway. They form a kind of frame that frames the doorway and closes the gaps between it and the wall. Cashing adds completeness to the interior and emphasizes the lines of the door. These molding elements for economy class MDF interior doors are manufactured from MDF. They also come in different types: figured, flat, telescopic, overhead and veneered. Flat strips are the cheapest and it is they, as a rule, that are equipped with the MDF interior doors discussed in this article.
Flashing (rebated strip) is a decorative part of the facade in the form of a strip, which is attached vertically along the edge of the canvas (outside or inside) with a projection that can partially overlap or behind the adjacent canvas. Installed on double doors, made of MDF. The shutter strip serves to hide the gaps between these two doors. As is the case with extensions and trim, it is matched to the color of the door set.
The threshold is an additional element of the door frame, which is the bottom crossbar of the frame. When installing a threshold, additional heat and noise insulation is created. Made from MDF. The threshold is often used when installing interior building doors as temporary entrance doors when completing construction projects.
As for the fittings, it should be added here that there are MDF interior doors with factory-installed fittings already embedded, and there are also those without inserts. In mortise doors, both the lock and hinges are already connected to the door block, and the customer does not have to waste effort installing them. This option is much easier to use, since assembling a finished box and placing it in the opening is much easier than carrying out all the insertion operations yourself. Independent unprofessional insertion of fittings is fraught with damage to the finish, the appearance of scratches, chips on the surface, and even more serious design defects. Doors with embedded fittings are correspondingly more expensive than their counterparts without inserts.
Advantages and disadvantages
Advantages of lightweight doors:
- reasonable price (cheaper than solid doors);
- light weight (max - 17 kg, which facilitates installation and reduces the load on the hinges and the box);
- high moisture resistance (when using high-quality PVC film and good vacuum sealing, this is really an advantage - the door, with some stretch, can be called airtight. In the case of paper films, we cannot talk about any moisture resistance);
- quite high resistance to point force impacts (this statement is true for high-quality doors and good film - PVC or double-chrome laminate. A trivial example - you should take a small metal object and press hard on pine doors. In most cases, a small hole or dent will remain - pine is very soft .High-quality films are durable and it is difficult to imagine the appearance of dents under the same force).
Disadvantages of lightweight doors:
- low mechanical strength (low strength is the downside of light weight, almost all doors with honeycomb filling are not strong - it’s not very difficult to break through such a door with your foot, or even your hand: cardboard is cardboard);
- low environmental friendliness (no matter how door manufacturers claim the highest environmental qualities of materials, they will never be higher than those of doors made of natural wood (provided that both types of doors are made of high quality);
- impossibility of repair (in case of mechanical damage, it is almost impossible to return to its previous appearance);
- low sound insulation (compared to solid doors);
- fragility of the product (suitable for installation in places with low traffic);
- high flammability (easily ignite).
Many apartment owners today install external armored and steel doors. It is necessary to choose the right external door, assessing not only the thickness of the metal in the door leaf, but also the characteristics of the filler. Good door performance depends on this. They need to be carefully researched to decide which door filler is right for your family.
Why is the internal filling of the door structure necessary? The purpose of these structural elements is to thermally and noise insulate residential premises from the influence of the outside world. As a result of the use of filler materials, the degree of rigidity of the door leaf increases. The quality of the internal filler and the ability of the external door design to perform its main functions are directly dependent. To understand which filler is best to use to insulate an external door, you need to find out what their characteristics are. Which door filler is best to choose? This question is asked by all people who have to solve the problem of purchasing a metal door.
What criteria should you use to choose these materials: what door filler to buy
- They must be safe for the environment and family members living in this apartment.
- Maximum insulation from external noise in a public corridor is necessary.
- The door must reliably retain heat in the apartment.
- The door leaf must be waterproof.
- The door should last a long time during its operation.
- What matters is the price that the apartment owner expects.
Each apartment owner has his own priorities when arranging his home. For some, the price does not matter, for others, silence in the house is important, and so on. But it is extremely important that living in the house is safe for all family members. Therefore, it is this criterion that must be taken into account first of all when choosing building materials to solve the problem of insulating the external entrance opening.
Mineral wool from rocks
Previously, the uses of this fibrous material were limited to the defense industry. And only now they began to use it in construction.
- This innovative filler is a universal material for thermal insulation and sound absorption.
- Its price is relatively low and accessible to everyone.
- This substance has a fibrous composition and is made from molten rocks or blast furnace slag.
- Mineral wool, which was obtained by the first method (stone wool), is a high-quality filler with excellent properties.
- This insulation is resistant to high temperatures, dampness and aggressive environments, and has low shrinkage.
- 6. Therefore, this substance is undemanding to operating conditions and can last for more than half a century.
- 7. This material allows for environmentally friendly filling of the door leaf, providing reliable protection for the room.
- 8. The excellent quality of mineral wool's resistance to ignition is used when installing fire-resistant structures and doors.
Builders consider this superior fire-resistant filler to be one of the most effective materials for filling door leaf structures. But all this applies to mineral wool made from rocks.
Slag wool: features
Mineral wool, which is obtained from blast furnace slag (slag wool), under unfavorable conditions of dampness, high or low temperature and various types of deformation, does not have the property of reliable durability.
This mineral wool has a big drawback. Over time, this substance settles. This leads to the formation of voids in the cavity of the door structure. To avoid this, manufacturers install additional frame ribs that prevent the filler from sliding down.
Typically, its scope of application is country house construction, the construction of temporary structures and structures that can be easily subjected to repairs.
Corrugated cardboard: advantages and disadvantages
This is an inexpensive door insulation with excellent properties. It absorbs noise. The special design of this filler is similar to a “honeycomb”. It is a corrugated cardboard frame inside a metal door.
- This material is characterized by rigidity, horizontal and vertical resistance. Corrugated cardboard is given rigidity by corrugated paper located between the cardboard layers.
- Its special composition does not allow moisture to pass through.
- Also, the advantages of corrugated cardboard include light weight, which does not burden the door structure, and relatively low prices.
- Low price, good heat and sound insulation are the undoubted advantages of this filler.
But this insulation also has disadvantages. Since it is thick paper, high humidity has a detrimental effect on it. For this reason, the service life of such external door structures is reduced if their tightness is broken.
Foam: effective, but can be dangerous
- This is a good heat-insulating material with excellent noise-absorbing properties.
- Its porous structure gives the filler excellent sound-absorbing qualities, frost resistance and non-hygroscopicity.
- Polystyrene foam is a harmless, environmentally friendly material that is durable and retains its performance qualities for a long time.
- Being one of the most effective heat-insulating materials, it has a very affordable price.
But a serious drawback is its extreme flammability. It melts and burns very quickly. When burned, they release a very large amount of toxic combustion products and toxic smoke. Such parameters do not allow us to consider polystyrene foam as the optimal option for filling an external door.
Foamed polyurethane
This is a material that contains many bubbles. Therefore, it is lightweight and durable. The voids in the door space are filled tightly with this filler. The modern construction market offers two types of polyurethane: elastic and rigid. The latter has the greatest application.
- It is highly wear-resistant, moisture-proof, durable, environmentally friendly, and effectively protects against extraneous sounds. This is a good insulator.
- Typically, this substance is used to install high-quality external doors, since it has a higher cost than mineral wool and polystyrene foam.
In addition, being a synthetic material, polyurethane filler is highly flammable and emits toxic substances. This can be an argument against such material when deciding what filler to find for doors.
Foampropylene: pros and cons
- Foampropylene combines very valuable features of synthetic materials - fillers for metal doors. This material has good thermal, hydro- and sound insulation characteristics for a long time.
- Its service life is designed to last up to 70 years, it is resistant to various loads.
- Its advantages include low weight, ease of installation, and resistance to chemicals. It is pumped under pressure and does not shrink, unlike mineral wool.
- The fire safety characteristics of this substance are much better than those of polyurethane filler and foam.
However, it is still a highly flammable material. And this is a serious disadvantage when choosing insulation. You need to keep this in mind when deciding which door filler to use.
It is up to the apartment owner to decide which door filler to choose. However, when buying a material, you need to meticulously evaluate its consumer properties. The insulating qualities of the door leaf are directly affected by the characteristics of the filler. When purchasing a door, you should look not only at its aesthetic qualities, but also find out what this door leaf is filled with. It is also useful to study the documents for these materials. In this case, you can make an informed choice and decide which insulation for doors to purchase.
Having analyzed and compared building materials that can be used as fillers for an external metal door, we can come to the conclusion:
- Comparing the thermal characteristics of expanded polystyrene and mineral wool, we can talk about their equivalence.
- In terms of noise absorption, mineral wool filler is more preferable.
- In modern conditions, the most preferable option for insulating external metal doors of economy class can be considered high-quality mineral wool (stone wool). It is this filler that can provide good insulating properties to an external door. Moreover, it is the safest. It is the safety of building materials that is taken into account when deciding which filler to choose for a door.
- When filling a business class external metal door, propylene foam and polyurethane foam are usually used, as they are more expensive and have good insulating qualities. But these materials are flammable.
The right choice of material for filling an external door will help make your home more cozy and comfortable.
Insulation problems are solved individually by each apartment owner.
Interior doors complement the design of our home. They delight the eye with their variety of laminated, veneered and painted surfaces. We don't ask ourselves what is in the middle of the product. It’s a pity, because the internal component – the filling – largely determines the sound and thermal conductivity of the canvas, and also affects its strength, ability to maintain geometry and service life. There are several types of filling: honeycomb, lumber, chipboard, tubular chipboard, etc.
Honeycomb filling of the door leaf
The era of aircraft construction (40-50s) began with the appearance of honeycomb fillers. They were used to lighten and give permanent shape to aircraft structures. The composition began to be actively used for interior doors in the middle of the last century, making them more durable, lighter, and cheaper. This type of filling of internal space is still one of the most common today.
Honeycomb filler consists of cells (honeycombs) made of pressed cardboard - corrugated cardboard, compressed with material enclosed in a frame. With the help of bars, the space near the lock is strengthened, and due to the air spaces in the cells, the filler makes the doors light (maximum 17 kg), facilitates installation and reduces the load on the hinges. All the advantages of honeycomb filling include moisture repellency and constant shape support. Such doors made of chipboard and MDF are given a marketable appearance: laminated, veneered or simply painted. Modern filler (impact-proof alloys, opaque materials) is used in leaves with a profile made of anodized aluminum (Al) - these are modern German doors made of aluminum (Al) and steel, in combination with glass.
Bar filling of the door leaf
Bar filler can be partial. The bars inside the door are located at a distance of 5-7 cm from each other, which lightens the door leaf and the load on the hinges.
Solid filler, when the bars fit tightly to each other - high sound insulation and the ability to withstand heavy loads.
Filling the door leaf with chipboard
Chipboard filler is obtained by hot, flat pressing of wood particles plus binder. This method is used to fill low-traffic economy class products.
Extrusion board - this filler is obtained by vertical pressing, the wood particles are perpendicular to the board, which increases strength. This filler is located between panels made of MDF, chipboard, HDF. To give it a marketable appearance, it is covered with veneer or enamel.
Extrusion - tubular filler is the use of slabs with voids (holes in the form of tubes) as an alternative to honeycomb. These are much lighter, hence easier installation, less wear on the hinges, and more economical, since little material is spent on the canvas. They are not afraid of large passages of people and can withstand pressure of 20 kg/cm. sq., shockproof, heat and noise resistant. This material best meets quality requirements.
The company's website presents products from various profiles with modern designs. A sales consultant will help you make the right choice; professionals will complete an order that meets your wishes, deliver and install it on time. The company has existed for 6 years in the construction market and has established itself as a serious partner.
The honeycomb filler in interior doors is corrugated cardboard pressed into a honeycomb shape. If you look at a cross-section of a door with such a filler, the filler will remind you of a honeycomb. As a rule, the design of a door with such a filler looks like this:
door frame (MDF or solid wood)
cladding (from plastic to solid wood)
block for installing a lock
corrugated cardboard filler
What are honeycomb doors made of?
Let's start with the door frame. It is no different from other types of doors - several beams. As for the filler, corrugated cardboard is just that: corrugated cardboard. Doors with such filling are suitable for low-rise buildings. This is due to the fact that they can withstand weights of up to eighty kilograms.
The functions of honeycombs in doors are as follows: 1) to fill empty space; 2) give rigidity to the interior door; 3) eliminate possible deformation of the door. Honeycombs can differ in hardness. There are more tough ones, and there are less tough ones.
In Russia, the most common type of honeycomb is honeycomb with a cell size of 45 millimeters and a compressive strength of 500 grams/cm2. This is the state standard. You should also remember that the size of the cells in the doors may vary depending on the manufacturer - not everyone follows state standards. Remember the main thing - the smaller the cell size, the better, the higher the density and rigidity of the honeycomb filler.
Advantages of doors with honeycomb filling
the main advantage is the price. Doors with such filling are inexpensive, but again we must not forget about the cladding. If you buy a veneer door with a honeycomb core, it will be more expensive than a PVC door with the same honeycomb core. For example, our Marco DG door in natural walnut color costs around 10 -11 thousand rubles.
environmental friendliness of the door. Unlike PVC and other synthetic materials, corrugated cardboard is environmentally friendly and safe.
resistance to changes in temperature and humidity conditions, resistance to light impacts.
a door with such a filler will be light. Within seventeen kilograms.
Disadvantages of doors with honeycomb core
The main disadvantage of honeycomb core is its soundproofing properties. If we try to evaluate on a five-point scale, we would give 2-3 points.
Another disadvantage of filler is that it is used to reduce the cost of door production. Hence the relative cheapness.