Brick dowel: types, installation instructions

It would seem that there is nothing easier than choosing a dowel for a brick.Moreover, it is more common and easier to install fasteners into a strong brick wall than into weaker foam concrete or aerated concrete. However, there are a lot of nuances in this matter that you need to learn about before choosing a specific dowel model.

Is a classic dowel suitable for fastening to brick?

There are several ways to install fasteners on a brick wall, including using a classic plastic dowel plug. Until recently, it was a simple nylon or polyethylene plug with a hole for a self-tapping screw. It didn’t matter how well such a dowel was held, but if you increased the number of fastening points, you could attach a kitchen cabinet or shelf to a brick wall.

The modern classic dowel is represented by a fairly large assortment of plastic plugs, differing in size, surface shape and material. And all of them can be used for mounting on a brick wall.

Traditional design of brick dowels:

• a cylindrical plastic plug with several slotted slits;
• conical spout to make it easier to insert into a hole in a brick;
• a belt at the end that prevents the dowel from falling into the depth of the hole;
• lateral tendrils that improve adhesion to the masonry material.

The best models of dowels with a diameter of 8 mm can withstand a pull-out load of 100 to 300 kg. Simpler universal dowel plugs of the same size hold 60-80 kg on a brick wall.

If you need to get a fastening on a brick wall for a load of 500-600 kg, then it is better to use chemical anchors.

It is clear that a pin glued into a brick can withstand a large load. But that’s not even the point; the load-bearing capacity of a chemical anchor, unlike an ordinary classic dowel, does not depend on the characteristics of the brick.

The problem is especially with brickwork. There are no two identical sections in it. Therefore, on a glued-in anchor, the strength does not depend on the installation point or defects in the baked clay, but on a conventional dowel it can vary greatly.

What to look for when choosing?

The strength of the fastening largely depends on which brick the dowel is fastened into and where exactly the fastening point will be located. White silicate walls usually hold fasteners better and do not crack even when using anchors. The strength of fastening on slotted hollow clay bricks, with the correct choice of dowel, can be even higher than that of solid stone.

Regular brick is red or violet-yellow. The first option is normal firing, the second is over-burning. Due to improper firing and a high content of aluminum oxide, the material turns out to be hard, brittle, plus a large number of cracks.

In both cases, the dowel inside a solid brick can “sit” firmly and reliably, but it happens that it falls out if it gets into a hidden crack.Much depends on which dowel you choose.

There are three options for installing a plug on a brick wall:

• directly into the body of the brick, retreating from the edges by 2-3 cm;
• in a vertical seam;
• in a horizontal inter-row seam.

If the masonry is old enough, at least 10 years old, laid with high-quality mortar, then you can beat dowels into the horizontal seam between the bricks. It is clear that you first need to check the strength of the cement joint with a chisel or screwdriver.

Often, installing a dowel in a seam provides higher fastening strength, but only if the mason did not skimp on the mortar, and this is very rare. But if you happen to hammer dowels between bricks, then you only need to hammer them inside the horizontal seam, and the diameter of the plug should be at least 10 mm. It is better to refuse installation in a vertical joint.

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What types of dowels are suitable?

In fact, not only classic dowel plugs are used for wall mounting. In addition to them, five more types of fasteners are used for brick walls:

• butterfly dowel, both plastic and metal versions;
• brass split anchors;
• steel propping anchors with reverse cone;
• façade fasteners for mounting heavy structures on walls;
• chemical anchor.

From the list of the most commonly used types of fasteners, dowels and anchor models for fastening to plasterboard, foam blocks and aerated concrete should definitely be excluded. Such fasteners have practically zero load-bearing capacity.

To fasten very light objects to a brick wall, you can use a dowel-nail. It can be made of polypropylene or nylon, but this has little effect on the strength of the fastening even on sand-lime brick.The maximum load for this model is 60 kg.

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Universal dowel

The most popular type of dowel is made of nylon, size 8x50 m, with a split slot and an annular knurling along the outer surface. The popularity of fasteners is due to their low cost and easy installation.

When installed correctly, the station wagon can withstand an axial pull-out load of up to 100 kg. When a universal dowel is driven into a hollow brick, the load resistance increases by 10%.

Imported universal dowel of special shape

It differs from the previous one in the side petals and the rectangular shape of the body. The design of the plug is thought out in such a way that when screwing in the self-tapping screw, the wedging of the body occurs in one plane.

It costs 2.5 times more than the previous model, but the load-bearing capacity is limited to 80 kg. But in a hollow brick, due to the crushing of the dowel and the formation of a plug, the attachment point can withstand up to 170 kg of pull-out load.

Triangular universal dowel

Type “U”, polypropylene plug with three edges, a cut and annular grooves on the surface. The cost is 3 times lower than the previous dowel.

This is one of the best dowel options for cases where you need to install a large number of attachment points. The cork can withstand a pulling load of up to 160 kg.

But for hollow bricks, it is better not to use the triangular option; even with proper installation, the strength of the fastener drops by 20%, from 160 kg to 130 kg.

German station wagon 8x60 mm

This type of dowel differs from previous models in that the body is made of two types of nylon: soft (red) and hard (gray).The cost of such a plug is approximately an order of magnitude higher than that of the previous sample.

In solid brick, “German” has a load-bearing capacity of 280 kg. That is, this is the best dowel if you need to make one attachment point, but with increased strength. In hollow bricks, the dowel can support a tensile strength that is 10% greater. The whole secret is that when you tighten the screw, the plastic is crushed in a special, precisely calculated way, reliably sealing the metal in the hole.

Important! If you turn the screw too quickly, the threads can cut the inside of the plastic and the fastener will fall apart.

Chemical anchor

A universal, but very expensive solution. It can be used for any purpose; M8 stud fasteners can withstand loads of up to 900 kg. But due to its high cost, the anchor is used only for particularly critical fastenings.

In hollow bricks, an anchor with a chemical filler can withstand loads of up to 1000 kg. In this case, the strength will increase over the course of several more days. When the polymer finally hardens, the resistance will increase by another 3-5%.

Instructions for installing dowels in a brick wall

The installation scheme in brick is no different from installation in other materials. But if you have to install a dowel in a burnt-out brick block, then it is better to immediately install a drill with a carbide plate into the chuck. High-quality brick, no matter whether solid or hollow, can be drilled quite simply with an ordinary metal drill. White silicate can even be drilled with a black wood drill.

Installation of classic plastic dowels in solid and hollow bricks

The easiest way to install a universal polypropylene or nylon dowel plug.Almost all inexpensive models have a cylindrical body with a supporting side and a pointed nose. The plug is held inside the hole only by compressing the annular notches to the inner walls of the hole. Therefore, you need to choose the drill diameter correctly; it should be 1-1.5 mm smaller than the cross-section of the plug.

Next, a hole is drilled in the brick; it is made with a small margin in depth. The dowel is inserted into the hole by hand. If the drill size is chosen correctly, the plug will go in about halfway. The rest will need to be driven in with a hammer until it settles at the level of the annular rim.

If the dowel needs to be placed in a hollow slotted brick, then the diameter of the mounting hole is chosen slightly smaller. When inserted by hand, the nylon body should go in about 1/3 of the way. Next, a self-tapping screw is inserted into the cork and screwed halfway. The rest needs to be screwed in with a screwdriver, while simultaneously inserting the dowel into the hole in the brick block.

You can, of course, do it according to the instructions, hammer down the dowel plug, then screw in the screw or hammer in a nail. But in this case, the fastening strength is 20% lower.

How to install a nylon self-twisting dowel

All universal dowels with a profiled surface, cuts, antennae are installed according to the following scheme:

1. A hole is drilled according to the size indicated on the marking. For example, 8x65 mm means that you need to work with an 8 mm drill to a depth of 65 mm.
2. The dowel plug is inserted by hand into the hole and hammered in with gentle blows of a hammer at the level of the side (if there is one).
3. A self-tapping screw is screwed inside the clogged plug.

If you make the hole 1 mm smaller, the dowel either will not fit inside the brick due to the “antennae”, or it will deform and break in the middle. Only a slight increase in the hole in a solid brick is allowed, and only at the entrance, and for dowels with a length of 80 mm or more.

For hollow slotted bricks, the hole is made exactly according to the dimensions on the marking. Accordingly, the fixation of the self-tapping screw occurs due to the self-twisting of the dowel into a tight plug.

Advice! When tightening a self-tapping screw or screw using a screwdriver, it is important not to overtighten the fasteners. You need to catch the moment when you need to stop the tool, otherwise the screw will cut out a part of the plastic with a thread and fall out of the masonry without any effort.

Installation of façade dowels

This type of fastener is used for installing heavy metal structures on brick walls. The length of the dowel screw is 120-180 mm. Facade dowels are installed on hollow and solid bricks according to the same pattern.

Initially, a hole is drilled, then a dowel plug is driven in and a screw is screwed in. No self-collapsing plug is formed. When screwed, the plastic expands with great force towards the inner walls and securely fixes the screw.

This is the only fastening scheme that can withstand any type of load, even variable, torsional and bending loads.

Chemical anchor

The installation scheme for hollow and solid bricks is practically the same. The only caveat is that the anchor can be installed in a full brick without a mesh sleeve, while inside a hollow brick - only with a mesh.

First you need to drill a hole, the dimensions are taken from the anchor markings. To improve adhesion, the cavity is cleaned with a brush and blown with air. A plastic mesh is then installed and a polymer resin, usually polyester or epoxy, is squeezed into it. All that remains is to press the pin inside with your hand and fix it until the resin has completely hardened.

What is the difference between dowels for concrete and brick?

Most often, fasteners designed for installation inside a concrete wall do not adhere well to brick. The same dowels or dowel-nails are “tightly” attached inside the concrete only due to the enormous contact strength of the material.

If you correctly wrap the dowel or drive a nail inside the dowel, the fastening will be held due to very strong deformation of the material. The deformation is small, but the bursting force is enormous, and the concrete does not crumble or crack.

Brick, as a rule, cannot withstand contact pressure, and the walls of the hole begin to crumble. For example, an anchor with a split brass sleeve inside concrete can withstand a load of up to 300 kg.

If you hammer the fasteners into the brickwork, the maximum load-bearing load will be only 60-70 kg.

The situation is even worse with the installation of reverse cone anchors. After drilling, the fasteners are installed with a small gap to reduce pressure on the walls of the hole. But still, even with careful and moderate tightening of the screw, the anchor cone almost completely destroys the front part of the brick.

If you leave it not completely tightened, the fastening will be weakened, the walls will gradually crumble, so the anchor will quickly fall out of the hole.

Results

Finding a good inexpensive dowel for brick walls is quite simple. Most classic models can withstand loads of up to 90 kg. This is quite enough for most household cases.If heavy-duty fasteners on the facade are required, then specialized models with an increased cork length can be used.

Tell us about your experience installing fasteners on brick walls. Which of them turned out to be the most reliable and durable? Write comments, share the article on social networks and bookmark it.