Features of expansion dowels

An expansion dowel is a type of construction and assembly hardware designed for fastening structures and equipment to solid foundations, most often walls. They are called spacer because of the characteristic type of fastening due to the friction created by means of movable wedges.

The expansion dowel complies with GOST 28778–90. Refers to construction and assembly fasteners. The dowel's task is to provide additional fixation of the main hardware (self-tapping screw) in the supporting structure. These products are used for installation and fastening in hollow bases, when other types of fasteners are ineffective.

The existing spacer wedges act as a buffer between the main structure and the bolt, self-tapping screws, ensuring the strength of the connection due to the wedging of the spacer part in the supporting base.

Dowels are made in several types of different materials:

• polypropylene and polyethylene;

• nylon and metal.

Depending on this, as well as the length and diameter, the dowels have the appropriate technical characteristics.

Manufacturers offer a wide range of fastening hardware, including many varieties of expansion dowels.

• Plastic with spikes. This type is considered universal. It is used for interior work, since plastic is not the most durable material and is easily destructible from the influence of temperature changes, exposure to moisture and the sun. They work with a polypropylene dowel with any surfaces, including concrete, stone.

• Nylon with spikes. Used for facade and other works. Special tendrils-spikes allow you to firmly hold the hardware inside the base. To work with this type of fastener, self-tapping screws with a diameter of 0.3-0.8 cm are selected.

• Drywall dowel. It is this type that is suitable for working with this fragile and unreliable material, unable to support simple fasteners and heavy weight. The special drill-point shape will allow you to do without a drill if the dowel is metal.

• Metallic with nut. It is used in most building materials, both solid and hollow: concrete and aerated concrete, brick and stone, gypsum panels. Suitable for fixing structures of medium weight: hoods, air conditioners, TVs. It has a smooth surface of the dowel, the spacer sleeve is designed in such a way that when driven in, it wedges tightly, remaining non-removable.

• Dowel nail. The hardware is intended for fastening lightweight structures to a base made of solid and hollow materials such as concrete, brick, chipboard, drywall, etc.

• Stud dowel. It is used for fastening light items: paintings, small shelves and wall cabinets. The hairpin is made of galvanized steel. Has excellent anti-corrosion properties.

• Four-way dowel. Fastening hardware, complete with a screw, is used for installation in solid bases: concrete, stone, brick.

• Brass Models used for shallow anchorage depths: handles, brackets, furniture fronts.

• Dowel clamp used in working with electrical wiring, for cable installation: the structure has a loop in the upper part to grip the cable, and in the lower parts there are spacer teeth that hold the dowel in the hole.

The size of the dowel is the diameter or width of the product and the length. A wide range of spacer models offers several lengths - from three or more options. The most popular sizes are 6x30, 10x50 and 6x37, the diameter of the dowel should correspond to the diameter of the hole.

• Four-spaced dowels are used for working with solid bases, they have sizes from 5x25 to 20x100. The greatest demand among them are 6x35, 6x50, 8x80, 10x100.

• Polypropylene, plastic universal models have dimensions 5x32, 6x37, 6x42, 6x52, 8x52, 8x72, 10x61, 12x71.

• Dowel-nails for working with concrete, stone, brick - 6x30, 6x40, 6x50, 6x60, 6x65, 8x50.

• Nylon for facade work - from 8x100 to 10x100.

• Dowel-stud, with the help of which lightweight structures are fastened, as well as all types of thermal insulation - 4x8x45, 10x50, 10x80, 10x90, 10x100 and up to 10x300.

• Metal dowel-crocodile, used in work with aerated concrete and other porous bases - from 8x30 to 10x60.

• Screw drilled nylon or metal hardware offer sizes 4.8x45, 8x55, 14x80, 10x60.

• The dowel-nail is produced in the following sizes: 4x40, 4.5x30, 4.5x40, 4.5x50, 4.5x60, 5x40.

The choice of a dowel is not easy. In order for the fastening to be reliable and of high quality, it is necessary to take into account the base material, its structure, the weight of the structure to be mounted, and its features. Fixing products with a large weight requires the selection of hardware with a fixing depth of at least 8.5 cm.

• Light items - wall cabinets in the bathroom, decorative shelves, wall clocks - can be fixed using expansion dowels with a diameter of 7 mm and a length of 3 cm.

• For the installation of heavy suspended ceiling structures - multi-tiered chandeliers, massive bronze lamps - you should choose fasteners with transverse notches and spacer antennae. In this case, it is important to observe the correspondence of the diameters of the hole and the hardware itself. For work with drywall, screw drilled models are most suitable.

• Metal dowel-crocodile is selected for the installation of structures to load-bearing bases made of aerated concrete, foam concrete and other porous materials.

• For the installation of heat and waterproofing manufacturers offer a dowel-hairpin with a disc head - the features of its head attach the insulating material more tightly and neatly, without the risk of damage. Such products with metal nails can withstand a lot of weight, but in the open air they are easily corroded, so it is better to choose the option with a thermal cover.

• For mounting brackets or facade profiles, lathing, front models are selected.

• For fixing electrical wires and cables manufacturers offer the best option in the form of a dowel-clamp. The loop of the clamp firmly grips the wire, and its serrated ends securely fix the entire system to the supporting surface. Excellent replacement for nails and other fixing devices.

For the correct use of spacer hardware, you need tools, adherence to technology and an algorithm of actions. In addition to the fasteners themselves, it is necessary to prepare an electrical tape, a sharp-pointed tool (nail or knife), a hammer and an electric drill with a victorious drill, a screwdriver or screwdriver, a hair dryer or a vacuum cleaner.

• On the surface, mark the installation location of the dowel, put a mark with a pencil. Then a small depression is made with a nail, the tip of a knife or other pointed object.

• They check the correspondence of the diameter of the drill and the dowel - ideal when the dowel is inserted by force into the prepared socket.

• On the drill itself, a piece of electrical tape marks the desired depth of the future hole, a little more than the length of the dowel itself.

• A hole is drilled, while the drill should be in a perpendicular position with respect to the bearing surface.

• The resulting hole must be free of dust and debris. It is blown out with a hair dryer or vacuum cleaner.

• The hardware is inserted all the way, while it is necessary to exercise the utmost care and accuracy so as not to damage the fastening device.

• After that, a screw is screwed into the dowel, a self-tapping screw with a screwdriver or manually - using a screwdriver.

The following video provides an overview of the dowels.