How to choose a metal door: 10 iron rules

Recommendation points

• What size should the door be?
• How to choose the thickness of the canvas?
• Which is the best rib system?
• Do doors need insulation and what?
• Why do we need safe doors?
• What loops are the most reliable?
• Which locking system to choose?
• How many locks should the door have and what?
• Does the presence of a peephole affect burglary resistance?
• What to choose a fastening system in the opening?
• How important are aesthetic qualities?
• What should be the completeness of a quality door?
• Conclusion

Cases of the correct choice of an entrance metal door that fully comply with the conditions of use and purpose are quite rare. We have collected several tips and rules to help you choose the right door in accordance with the requirements for it and not overpay.

The cost and complexity of the front door device should be determined by its burglary resistance. It, in turn, should be consistent with the value of the property and the likelihood of an attempted illegal entry. In any case, it is necessary to take as a golden rule not to provide excessive resistance to hacking and carefully check whether the proposed technical solutions are really capable of performing their functions..

What size should the door be?

The actual size of the door is determined by the dimensions of the opening, from which the values ​​of the technological gaps and the thickness of the door block post elements are subtracted. The width of the opening according to SNiP should not be less than 910 mm, the height can vary from 210 to 230 mm, taking into account a 70 mm thick stand, which cannot be knocked down. However, these norms are directly related only to secondary housing; in new buildings and on private objects, the dimensions of the openings can be completely arbitrary..

Therefore, it is so important to monitor the observance of the technological clearances for correct installation when measuring. The opening in panel and precast-monolithic buildings should be at least 10 mm larger than the assembled door block on each side, in brick – by 25 mm. It is desirable that the gap is no more than 50 mm, this will lead to a “suspended” method of installation, reduce the strength of the fastening and will not allow using the door for the first time after sealing.

How to choose the thickness of the canvas?

The thickness and grade of sheet steel in the door leaf is one of the most important factors in burglary resistance. In general, the thicker the door is, the more reliable it is, but you should not bend it. Firstly, the vandal opening of the canvas is carried out only if comparable forces failed to break the locks. Secondly, due to the increased weight of the door, it will be necessary to strengthen the hinge group. Door leaves weighing over 150 kg require the installation of a closer and an opening limiter. The optimal sheet thickness ranges from 1.5 to 3 mm, and for doors of burglar resistance class III and IV – at least 4.5 mm.

The material for making the canvas is much more important. The hardness of the steel to resist the axial tool must be at least 55 HRC, for resistance to most cutting edges 35–40 HRC will be sufficient. The drilling and cutting resistance of steel is almost irrelevant for composite blades in which a layer of abrasive material is sandwiched between two relatively thin sheets of steel. You also need to remember that the hardness of steel below 60 HRC is not decisive for resistance to abrasive and oxy-fuel cutting, most of the so-called burglar-resistant blades can be burned with a hand-held balloon cutter.

Which is the best rib system?

High web stiffness is one of the most important barriers to spinning. Most budget doors have only a thin corner steel frame and a stamped surface. In this case, the door is indeed curved with difficulty, but with a metal thickness of less than 1 mm, it can simply be crumpled.

It is optimal if the door is reinforced along the contour of the porch with a rectangular profile with dimensions of at least 40×40 mm with a wall thickness of at least 2.5 mm. You can also focus on the cross-section of the reinforcing element, it should not be lower than 400 mm². In addition to the framing frame, it is desirable to have one or two horizontal braces and diagonal braces in the formed cells. Too tricky reinforcement system should not be fenced: stiffening ribs negatively affect heat and noise insulation, increase the weight of the canvas.

Do doors need insulation and what?

The so-called insulated doors will be more correctly called filled, because the material inside the canvas provides not only a decrease in heat loss. It is also a sound insulator, in some cases interspersed with layers that make it difficult to make a full passage.

Thermal insulation is a mandatory option for the front door of a private house, even if there is a vestibule. In other cases, filler is not required. Honeycomb corrugated board, expanded polystyrene and PUR-filler have the best performance in ascending order. Mineral wool for doors is not quite suitable: after several years of operation, it shrinks with the concomitant formation of cold bridges.

Why do we need safe doors?

The safe door is a sheet that does not protrude beyond the plane of the installation box or casing to exclude the possibility of wringing out with a lever tool. At the same time, such a door is filled with concrete inside to increase anti-vandal resistance..

Almost all safe-type canvases belong to the fifth, highest class of burglary resistance. However, it makes sense to install such a door only if it is equipped with locks of the appropriate class, moreover, such a choice should always be due to practical necessity. Otherwise, the safe door becomes a useless investment of money: it is 2-3 times more expensive than the usual one due to the complexity of organizing the unlocking system and the need to install a reinforced hinge group.

What loops are the most reliable?

There are a lot of loop designs, but in general they can be divided into two groups: hidden and external. The latter type is simple and cheap, most heavy, but inexpensive metal doors are equipped with visible hinges. This is due to the fact that they can withstand the high weight of the canvas much better, in addition, the door frame is cheaper due to the unnecessary use of a hollow profile and the device of seats for hidden mechanisms. However, visible hinges are worse in terms of burglary resistance, it is recommended to purchase a hinge group made of hardened steel with rotating pins, which are very problematic to cut.

Flush-mounted hinges are complex multi-piece hinges. Their advantage is the lack of direct access to the hinge group and maintaining the integrity of the outer side of the web. Providing high burglary resistance, they have characteristic disadvantages: they need adjustment and maintenance, they can creak and sag over time due to metal fatigue. If, when completing a blade weighing over 200 kg, the choice fell on hidden hinges, it is better to purchase the highest quality product possible, thereby guaranteeing a high service life.

Which locking system to choose?

Modern doors are closed not only directly with the pins of the lock. A synchronous locking mechanism is usually located in the cavity of the door leaf, which, when the lock is turned, expands the crossbars on three sides of the porch. This is good and bad at the same time: a door with such a system is less susceptible to squeezing, but at the same time a burglar can gain access to the mechanism through a window cut in the canvas, thereby bypassing the secret of the lock.

It is optimal if the locking mechanism is located in the cavity of the profiles that act as stiffeners, or the central unit together with the lock will be closed with an armored plate. Also, the system of passive transoms located on the hinge side will not damage.

How many locks should the door have and what?

To answer this question, let us turn to the configuration of the classic factory-made doors, which are often unknowingly called Chinese. They have three locks: the upper one, otherwise called fast, the lower one, which sets in motion the locking mechanism on the vestibule, as well as the “night” valve, which has no physical possibility of opening from the outside. Such a set of locks is basic, in modern doors it cannot be more scarce.

Burglar resistance can be increased, for example, by replacing the central cylinder lock with a lever lock. The highest class of burglary resistance is characteristic of locks with the possibility of reprogramming for a new key, as well as those equipped with a secret-trap that resets the locking bolts when trying to move the lever separately. Opening such locks is possible only by making a duplicate key from a mold. It is possible to further increase the resistance to burglary by installing a radio lock or a hidden drive of the locking mechanism, but in this case it is imperative to monitor the technical serviceability and maintain the charge of the built-in battery.

Does the presence of a peephole affect burglary resistance?

It is believed that the hole under the door peephole greatly reduces the opening time. Indeed, if a burglar is familiar with the structure of a typical door, knocking out a peephole, he can manually set the internal mechanism in motion. Also, the hole for the peephole serves as a vulnerable spot in case of a vandal break-in: through it you can start cutting the canvas without noise and unnecessary effort using lever scissors.

Of course, you can only avoid the peephole if you install a video intercom or a hidden surveillance camera. In other cases, it is recommended to purchase a modern type visor with separate fastening of the body halves. Its peculiarity is that the diameter of the mounting hole does not exceed 5–6 mm, which is not enough for the entry of the scissors. Also, instead of a peephole, you can install a camera, for the connection of which a hole of 2–2.5 mm will be enough, through such a gap, manipulations with the internal mechanism are absolutely impossible.

What to choose a fastening system in the opening?

If neither the canvas nor the locks lend themselves to burglary, attackers can try to vandalize the entire door block. This is all the more possible if the technological gaps are not observed during the installation process, or due to the filling of the assembly joints with foam, and not with cement mortar. It is possible to complicate the task of burglary by ensuring high-quality fastening of the door block.

We are talking about a system of anchors buried in the body of the wall for at least 1/4 of the width of the canvas. For anchors, ordinary steel reinforcement is suitable, which was inserted into the boreholes before the block was installed in place with a step of 80-100 cm along the perimeter of the opening. After positioning and fixing the door, its flashing box is welded to the anchors, thereby the block acquires an almost monolithic connection with the wall. Naturally, this installation method will not work when installing doors made of sheet metal..

How important are aesthetic qualities?

Do not be surprised, but the outer finishing of the door is most directly related to ensuring high resistance to burglary. The presence of an overlay glued over the entire plane allows you to hide the manufacturer and model of the door, the type and quality of steel. Also, burglars will not be able to appreciate such specific subtleties as welding marks or the location of hidden loops..

The overlay should not be provocatively pretentious, a smooth MDF sheet with bevels is enough. In this case, it is recommended not to install branded keyhole covers that come with the locks. It is much better to use hardware without identification marks, this will make it difficult to determine the model of the lock.

What should be the completeness of a quality door?

The door installation process must be monitored personally, to monitor compliance with the geometry and positioning of the door unit. In this case, the assembly team must remove the internal decorative overlay, demonstrating the presence and conformity of the type of insulation, as well as showing the customer clearly the principle of operation of the synchronous locking mechanism.

The classic set of the door block is as follows: the door leaf complete with locks, hinges and other fittings, a flashing frame and outer platbands. The finishing of the internal slopes is carried out by the customer independently from the accessories for the interior doors. Another important point: it is imperative to make sure that the set of keys is sealed in an opaque bag with factory markings and intact seals. All locks pass the first test at the installation site, in the event of a factory defect, the door manufacturer is obliged to replace them within the agreed time frame.

Conclusion

As a summary, it remains only to remind you that when choosing a door, you definitely need to know when to stop. The correct blade, locks and installation system can provide a really high resistance to burglary, however, the more difficult it will be for emergency services personnel to act in the event of an emergency..