What is a soundproof door

We continue the conversation about what doors are. This time we will focus on doors, which experts call soundproofing, or soundproofing. It is clear that the main task of such doors is to reduce noise entering the room (or vice versa – from the room). How do they differ from ordinary standard doors? First of all, by the fact that they fit snugly to the door frame and the floor (thanks to all kinds of seals and sills). And also by the fact that inside them, as a rule, there is a sound-absorbing filler.

Where you need a special soundproof door?

Sergey Korolev, manager of the Spark-Plus company, works with the VEKA profile:

– Any door is soundproof. But not every door protects against noise equally. If you need to eliminate only a few decibels (dB), then the usual “cardboard” is enough. … A door made of chipboard or PVC profile can reduce noise by 27-30 dB. That is, in this case, the entrance noise will not penetrate inside (since the human ear does not perceive noise less than 15 dB). But if we are talking about special rooms, for example, recording studios, then increased requirements for sound insulation are imposed on the doors. But you must definitely remember that it makes no sense to make the door more noise-resistant than walls and ceilings..

Konstantin Vasiliev, director of Parsal:

– It makes sense to talk about a soundproof door only when soundproofing of walls, windows and ceilings is provided. This is especially important for rooms with lightweight interior partitions (for example, made of plasterboard), even put the most deaf door there – you can still hear what is happening behind the partition. All other things being equal, the heavier and thicker the door, the better it protects against noise. For example, a thick lead door will not let in a single sound. But it is unthinkable to put a door with such a weight in our houses, and it is not necessary. In the range of 30-40 dB, a relatively light (up to 80 kg) door made of chipboard or MDF will protect.

So, as we can see, under normal conditions, you can do without a special soundproof door..

For example, according to experts, a massive oak or pine door significantly reduces the noise level. In addition, fireproof doors have good anti-noise properties: a heat insulator is laid inside them (it is also a good sound insulator). For example, sound insulation of fire doors by the German company “Hermann” – in the range from 36 to 45 dB.

Steel doors have sound insulating qualities if an insulator is laid between the steel sheets (better if it is mineral wool). Moreover, without such an insulator, a steel sheet can, on the contrary, increase noise..

But nevertheless, if there is a desire and need for more reliable protection from noise, you can make a soundproof door from an ordinary door. Let’s see how to do it..

How to reduce the sound transmission of a conventional door?

The easiest way is to upholster the door with leatherette or natural leather, laying a layer (or several layers) of batting or synthetic winterizer under the upholstery. Moreover, the thicker the “soft pillow”, the less noise will pass through the door. It is better if the masters hug the door on both sides. In addition, you can upholster the door with wood or chipboard (but keep in mind that in this case the door becomes heavier, so it is better to supplement it with one or two more hinges).

A more complex design is to install two doors with a vestibule between them. The air gap in the vestibule will reduce the noise level.

Sealing gaskets that close the gaps between the door frame and the door leaf well reduce the noise level. They are attached to the door leaf so that a ledge is formed on the door, covering the edge of the door frame. According to Maxim Rodanov, a representative of the Spanish company Artevi, which supplies a variety of doors to our market, “with gaskets, noise passes through the door by 30-40% less”.

What is a soundproof door?

But let’s say a regular door doesn’t suit you. Suppose there are noisy companies gathering on your landing. Or, for example, you are a musician and rehearse at home, but you don’t want to disturb your neighbors. Then you need even more reliable soundproofing. That is, as experts say, you need a door leaf of a special design (not counting, of course, sound insulation of walls, windows, etc. But this is a separate conversation).

So, the outwardly special door does not differ from the standard one. The whole difference is in the internal structure. The special soundproof door in the cut resembles a layer cake. For example, the Finnish Alavus doors consist of two MDF panels, painted on the outside, between which pressed mineral wool is laid. Sound absorption level of such a door is 30 dB.

Soundproof door filling (from left to right): 1 – honeycomb base made of cardboard; 2 – chipboard with tubular cavities; 3 – solid chipboard

The Finnish Suomen Ovi doors have even more layers. Inside – a core, a chipboard sheet, insulated on both sides with a soundproof film, and outside – a painted chipboard. Sound absorption level – 30 dB.

The German company “Westag and Getalit AG” (Westag & Getalit AG) also makes multi-layer doors: chipboard – fiberboard layers – laminate. Doors “Westag and Getalit AG” (Westag & Getalit AG), depending on the model, they delay from 27 to 42 dB.

The doors of the Russian company Parsal are finished with laminate on the outside, and 2-3 layers of chipboard covered with plastic inside. Sound absorption level – 30 dB.

The industrial group “Hobbit” sells doors from the German profile “Veka”. The filling is a double-glazed window or an opaque sandwich-type filler. Sound absorption level – 28 dB.

What to choose?

It all depends on what the door is for. If it is required to soundproof a special room, then a special door is also needed (plus insulation of walls, windows and ceilings). And if you need to get rid of the usual external noise (street noise, stomping on the stairs, the hum of conversations), then it is quite possible to soundproof the existing door, as we have already said, with the help of upholstery and seals. Or purchase a ready-made one that suppresses about 30-40 dB on average. Often two ordinary (for example, wooden) doors “reduce the volume” more than one soundproof door. And two soundproof – even more so!

According to SNiP P-3-79, a soundproof door must hold at least 26 decibels (dB). That is, if the noise level on the outside of the door is, for example, 56 dB, then inside the room – no more than 30 dB. And on average, “comfortable volume” for a person is from 30 to 50 dB.

Errors and ambushes

Karen Aslanyan, Vestag & Getalit AG:

– The company is not responsible for the door in the event of a change in its design by the owner. If, for example, after the installers leave, the owner, on his own initiative, inserts a peephole or an additional lock into the door, then the soundproof quality of such a door will certainly be reduced..

The second common mistake is inaccurate measurements..

Installer Nikolay, Parsal firm:

– There was a case when the customer made measurements on his own. Under his responsibility, we agreed to fulfill the order. And when the door was brought to the place, it turned out that it was larger than the opening. You cannot saw it, as there is a sound-absorbing seal and a sill along the edge. We decided to make the opening. We started to work, but the police immediately arrived. It turned out that the neighbor called the outfit: she didn’t like the noise. In general, the customer got angry and ordered a new door, but with our measurements. And it cost him more than the first one, since the unfinished work with the opening had to be interrupted, and then everything was restored as it was.

Therefore, I appeal to everyone who wants to install a soundproof door – invite a measurer!

Soundproof door accessories

Door frames. They can be metal or chipboard. The inside of the metal box is filled with concrete, and the chipboard boxes are filled with polyurethane foam. The smaller the gap between the opening and the door frame, the better. According to the rules, the gap should be no more than 1 cm.

Sealing gaskets installed around the entire perimeter of the door frame. The Swedish rubber gaskets “Varnamo” or German (also rubber) “Fomestrip” have proven themselves well..

There should be a sill at the bottom of the soundproof door. For example, at the doors of Vestag and Getalit AG there is an automatic magnetic sill: below – instead of a threshold – a magnetized rail is sunk into the floor.

When the door is closed, a metal plate is attracted to the magnet, and thus the gap between the floor and the door is eliminated (this mechanic is called “aluminum magnetic floor seal” in the catalog). When the door is opened, the metal plate automatically slides into the door. Instead of a plate, a special rubber pad can be pressed to the floor in the same way – then the magnet is not needed.

Expert opinion

Is it possible to make a soundproof door fireproof?

Director of the Non-Commercial Partnership for Fire Safety “Pulse” (NPO “Pulse”) Victor Baraleichuk:

– How to make the door not only soundproof, but also fireproof? You need to buy a door with a so-called fireproof sound insulator. (Such a door is manufactured at the factory, and a certificate is necessarily issued, and it indicates the time during which the door remains intact in the event of a fire.)

To date, the best fire-resistant sound insulator is mineral wool based on high-density basalt fibers (150 kg / m3). It is especially good if 2-3 slabs of such mineral wool are laid inside the door. In addition, if the door is metal, there should not be so-called “thermal bridges” inside it (that is, metal parts connecting the inner and outer sides of the door leaf). Because it is through them that the heat will easily reach the intact side of the door, and then the inner upholstery will start to melt and light up.

Many factory-made fire doors provide noise absorption of more than 30 dB (this should also be indicated in the certificate). As a rule, this is quite enough for city apartments..

For those who want to modernize their old door on their own, I recommend putting a layer of mineral wool based on basalt fibers (about 10 mm thick) from the inside, and upholstery with leatherette on top. This will increase both the sound insulation and the fireproof properties of the door. But in no case use foam rubber and batting: in a fire, they quickly ignite and, even worse, emit poisonous combustion products.

In addition, the outside of the door can be upholstered with a thin (0.5 mm) metal sheet (for example, galvanized) and painted on top. If the door is new and not yet painted, then the surface of the door leaf can be treated with a fire retardant, for example, domestic KSD, OSP-1, OZP-D, VANN-1, etc..

Typical noise sources

Airplane takeoff 160 dB
Scream 90 dB
Noise on the train when driving 85-90 dB
Busy street noise 55-60 dB
Conversation in a medium-sized room 45-50 dB
Noise in a quiet street 30-35 dB
Whisper at a distance of 1 m 25 dB
Quiet garden 20 dB

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