Installation of bathroom accessories: anchors, wall plugs, and mounting on different types of walls

Installation of Bathroom Accessories: Anchors, Wall Plugs, and Mounting in Different Wall Types

What seems to be a simple task – drilling a few holes and attaching a bracket – can become quite complicated in the bathroom. The walls in the bathroom are often not what they appear to be at first glance. Behind the tiles, various base materials hide, the thickness of grout and adhesive mortars varies, water and electrical installations lurk in unexpected places, and humidity turns an improperly chosen wall plug into a piece that will unexpectedly fall off the wall in a year without warning. In this article, I will systematically cover the entire topic of mounting bathroom accessories: from identifying wall types, through the correct selection of anchors and wall plugs, to the specific installation procedure and the most common mistakes from practice.

Why Installation in the Bathroom is Different from Installation Elsewhere

The bathroom combines three unpleasant factors at once: humidity, ceramic tiling, and relatively small space. Each of them alone would be enough to require increased caution, but together they demand a systematic approach.

Humidity mainly affects the long-term stability of the anchor. Gypsum plaster, which is quite common in bathrooms as a base layer, absorbs moisture and loses strength after repeated wetting and drying. A standard plastic wall plug designed for dry environments will disintegrate under such conditions in a few years. Moreover, if water penetrates the drilled hole, in unheated recreational buildings during winter, freezing and cracking of the wall plug socket can occur.

Ceramic tiling adds another layer of complications. Tiling is a hard, brittle material that cracks, breaks, or gets radial cracks when improperly drilled. The layer of adhesive behind it can be 3 to 15 mm thick depending on the laying method. Only then comes the actual wall – and it can be masonry, concrete, drywall, or hollow aerated concrete. These layers differ in strength and require different anchoring methods.

The small space of the bathroom also means that accessories must bear the load in unfavorable positions. Mounting on solid masonry at a height of 1.5 meters with a long arm bracket for towels creates a significant bending moment. A screw that would normally hold in the wall can loosen under dynamic loading (e.g., stretching a wet towel, holding on in the bathroom...).

Identifying the Wall Type Before Starting Work

Before any installation, you must know what is behind the tiles. There are several ways to find this out without breaking anything:

Tapping Tests and Magnetic Probe

Tap the tile with a padded fist in different places. Solid masonry sounds muted and firm, hollow aerated concrete or Ytong slightly resonates, and a drywall partition (so-called "dry masonry") sounds distinctly hollow and ringing. If you detect hollow areas only in certain places, it may be wall cavities in a standard masonry block (e.g., Porotherm).

Pass a magnet over the wall – it can help identify the structure by hitting metal anchors of drywall profiles or reinforcing mesh in concrete. A metal detector and an electrical cable detector are an investment that always pays off when installing a large number of accessories – and in the bathroom, they protect you from puncturing a water pipe or revealing a live wire.

Thickness of Grout and Adhesive

From the side of the baseboard or near a switch, you can sometimes see the wall profile. The standard thickness of the tile is 6–10 mm, adhesive mortar 3–15 mm, and sometimes thermal insulation boards are added. Altogether, this can be 15–30 mm of "dead" material before the load-bearing wall. The wall plug must anchor in the load-bearing material, not in the adhesive mortar.

Types of Load-Bearing Materials and Suitable Wall Plugs for Each

Distinguishing load-bearing materials is key because each has a different tensile strength and the mechanism of force distribution in the wall plug works differently.

Solid Bricks and Lime-Cement Plaster

Classic solid bricks (so-called CDm) with plaster are the most favorable material for anchoring. A standard wall plug screw 6×50 mm or 8×60 mm can handle a tensile load of 0.5–1.2 kN. For most bathroom accessories, this is more than enough. Use wall plugs made of polypropylene or nylon (PA6) with a longitudinal expansion mechanism. Chemical anchors are also suitable for solid bricks, but for standard accessories, this is an unnecessary overdimensioning.

Perforated Bricks and Aerated Concrete (Ytong, Siporex)

Here is where things get complicated. Perforated bricks (e.g., Porotherm 17.5 or 25) have internal air channels. A standard expansion wall plug will expand into the void and will not transfer the load. The solution here is:

• Wall plugs with large expansion wings (butterfly wall plugs, so-called "Molly bolt" or "butterfly") – they expand behind the cavity and hold by the principle of pressure counter-surface
• Long nylon wall plugs with low pressure distribution (e.g., Fischer GK or SXR) designed for hollow bricks
• Chemical anchor in aerated concrete – injected resin fills the pores and creates a mechanical bond; load capacity 0.3–0.8 kN depending on the density of the aerated concrete

Autoclaved aerated concrete (Ytong) also has very low hardness – you drill it with almost no resistance, which can mislead a beginner into thinking that the anchoring is secured. The opposite is true: the material is brittle and crushes under point load. For heavier accessories (electric dryer, massive shelf), consider distributing the load over a larger area using an anchor washer or use 3–4 anchors instead of 2.

Concrete and reinforced concrete

Concrete walls are ideal for anchoring in terms of strength, but they place increased demands on drill bits and the power of the drill. For concrete, you always need a hammer drill or a hammer drill bit (SDS-Plus), otherwise you will only wear out the drill bits. A standard expansion anchor screw M8 in concrete can withstand a load of 2–5 kN, which is more than sufficient for a bathroom. Pay attention to the minimum distance from the edge of the concrete (at least 5× the diameter of the drilled hole), otherwise there is a risk of edge chipping.

Gypsum board partitions (drywall)

Gypsum board (GKB, GKBI – impregnated for wet areas) is becoming increasingly common in modern bathrooms. Anchoring directly into the board without a stud is limited – the gypsum board alone without support can hold almost nothing (long-term load max. 10–20 N directly into the panel). Therefore, the following rules apply:

• Anchor into the profile (CW/UW) – the best solution, the profile is made of galvanized sheet metal and screws into metal M4–M5 there can safely hold a load of 0.3–0.8 kN
• Special hollow wall anchors – Toggler, Molly, Fischer Dübel GK – expand behind the board, load 0.2–0.5 kN depending on the board thickness
• Pre-installed block of wood or metal – in a planned bathroom, it is ideal to insert a wooden block 40×60 mm between the profiles where the accessories will be; screws can then anchor into it just like into masonry

Drilling into tiles: how to do it without cracking

This is the chapter where the most mistakes are made. Ceramic tiles are hard and brittle at the same time, and a standard hammer drill can crack them in a fraction of a second. The correct procedure:

Drill bit selection

• Drill bit with diamond/tungsten carbide tip (so-called "tile drill bit") – specially ground tip geometry without hammering, diameter 4–8 mm, price 3–10 €/piece
• Triangular drill bit for tiles – a cheaper version, works on standard ceramic tiles, not on rectified porcelain tiles with hardness above 7 Mohs
• Diamond core drill bit – for very hard porcelain tiles, drilling with water cooling

Step-by-step drilling procedure

1. Mark the spot with a pencil or colored tape (the tape also prevents the drill from slipping on the smooth tile surface)
2. Stick a circle of masking tape on the spot of the hole – the drill will not slip at the start
3. Set the drill to low speed (400–800 RPM), hammering OFF
4. Drill the tile without pressure, let the drill do the work, after piercing the tile it will reach the adhesive
5. After piercing the tile and adhesive, switch to hammering (only if the load-bearing material is concrete or brick)
6. Continue drilling to the required depth in the carrier (minimum 30–40 mm anchoring depth)

Important note from practice: never start drilling at a joint or in the corner of a tile – that is where the highest stress concentration is and the crack spreads immediately. The ideal position of the hole is in the center of the tile, at least 3 cm from the edge.

Special case: Porotherm, hollow bricks and perforated lime-sandstone

From practice, I know that these materials cause the most "mysterious" cases, when an accessory holds for a day and then falls off the wall. The problem is that the course of the hollows is not visible from the outside and a classic expansion anchor can sometimes expand into the hollow, sometimes into the material – the result is random.

Proven solution for Porotherm and similar materials:

• Chemical anchor (injected resin) – drill a hole, blow it out with compressed air, fill it with resin, insert the anchor rod and wait for it to harden (30–60 min at room temperature). Load capacity up to 2 kN.
• Fischer Dübel SXR or Rawlplug R-LX – special long anchors with low expansion pressure, designed for hollow materials
• Butterfly mechanism anchors (Molly) – mechanically expand behind the hollow wall, good for loads up to 500 N

Choosing the right screws: material and dimensions

The screw is just as important as the anchors, and in a bathroom, the choice of screw material is especially important. Standard galvanized screws are doomed to rust in the bathroom's humidity – and this rust then stains the tiles, which is an aesthetic disaster, but also a hygiene problem.

Always choose the following for the bathroom:

• Stainless steel screws A2 or A4 – ideal for a humid environment, A4 stainless steel resists chlorides (swimming pools), A2 is sufficient for standard bathrooms
• Plastic screws – for light accessories and aesthetic reasons (no rust), limited strength
• Zinc-coated screws with silicone sealing washer – a compromise when stainless steel is not available, but only a temporary solution

Screw dimensions for standard bathroom accessories: M4×25 mm to M6×50 mm, ring or half-spherical head for aesthetic coverage with a cap, screw clearance matching the inner diameter of the anchor (an anchor for an M5 screw has a 5 mm hole inside – this is not the same as the outer diameter of the drilled hole, which is usually 8 mm).

Practical installation process for bathroom accessories – step by step

I will demonstrate the exact procedure using the example of installing a 43 cm stainless steel towel rack or a 48 cm stainless steel towel rack in a standard bathroom with ceramic tiles on a brick wall.

Detailed procedure with dimensions

Step 1 – Marking positions: According to the attached mounting template (included with most accessories) or according to the spacing indicated in the instructions, mark the drilling positions with a pencil. For a rod towel rack, a typical distance between anchor points is 150–350 mm, always check with a spirit level. Mounting height: for an adult, typically 90–110 cm from the floor for a horizontal rack, or 130–160 cm for vertical hooks.

Step 2 – Checking wiring: Before drilling, ALWAYS check the detector for electrical wiring and, if possible, also the expected route of the plumbing. Water supply and drainage pipes usually run vertically behind installation columns (a vertical strip of wall behind the bathtub/shower area), electrical wiring runs horizontally at the level of switches and sockets. Horizontal electrical wiring under the ceiling (about 15–30 cm from the ceiling) and above the floor (about 15–30 cm) are other typical routes.

Step 3 – Drilling the tiles: As described above – special drill bit, low speed, without impact. Drill bit diameter: usually 6 mm for M6 anchors, 8 mm for M8. Before drilling, stick a circle of masking tape on the tile surface.

Step 4 – Drilling the load-bearing wall: After drilling through the tile and adhesive, switch to a standard drill bit with impact (brick, concrete) or a special drill bit for aerated concrete (without impact, larger diameter – aerated concrete anchors have an outer diameter of 10–14 mm). Depth of the hole: tile thickness + adhesive + at least 40 mm in the load-bearing wall = usually 55–70 mm in total.

Step 5 – Anchors and sealing: Apply sanitary silicone to the drilled hole, insert the anchor fully (the end of the anchor must be flush with the surface of the tile or 1 mm below the surface). Apply a small bead of silicone around the hole in the tile – it seals the transition between the anchor and the tile.

Step 6 – Installation of accessories: Align the brackets or mounting plate of the accessory, insert stainless steel screws and tighten to center it. Most premium series accessories allow for minor position adjustment before final tightening. After tightening, check with a spirit level and seal the joint between the bracket and the tile with sanitary silicone (prevents water seepage and also aesthetically closes the joint).

Installation of system rails and WallStoris accessories

Modular organization systems, such as the WallStoris wall rail length 500 mm matte white, have a specific feature in that the load-bearing rail must support not only its own weight but also all suspended accessories, including WallStoris towel holder length 581 mm matte black, trays, baskets and other accessories.

For longer rails (400–600 mm), it is critical that the anchoring is not only at the extreme ends. A 500 mm rail should be anchored at a minimum of 3 points – at both ends and in the center. If possible, both end anchors should hit a solid wall or a gypsum board profile, not a hollow space. Anchoring in the center distributes the bending moment and prevents the rail from sagging under load.

Before installing the rail, think about where you plan to hang the accessories – heavier items (hair dryer, soap dispenser with content) should be concentrated near the anchoring points, not in the middle between them. For more on how to plan the placement of accessories, see the article Organizing a small bathroom: where and how to place holders, rails and storage accessories.

Installation of electric towel dryers

An electric towel dryer is a special case, as in addition to mechanical anchoring, you also need to address the electrical connection. Electric dryer 2 arms white usually has a power of 60–120 W and requires a socket in close proximity or a pre-prepared electrical supply in the wall.

According to the standards valid in Slovakia: electrical appliances in the bathroom must be located in zone 2 or 3 (not zone 0 and 1 – i.e., in direct contact with water or directly above the bathtub). Zone 2 is an air distance of 0.6 m from the edge of the bathtub or shower area. In zone 2, appliances with IP44 or higher protection are allowed. An electric dryer with IP44 protection can therefore be connected to a standard grounded socket in the bathroom, but the socket itself must also be IP44 and must be protected by a residual current device (RCD) of 30 mA – which is standard in modern bathrooms.

Mounting the dryer is mechanically more demanding than mounting a passive holder, because the dryer is heavier (3–8 kg) and heat transfer during repeated heating and cooling dynamically stresses the anchoring. Use at least M5 screws into nylon anchors with an anchoring depth of 45 mm in brick masonry, or chemical anchoring for aerated concrete. For more detailed information on choosing a dryer, read the article Electric towel dryer: how to choose power, type and installation method.

Most common mistakes and how to avoid them

From practice, I know these recurring mistakes that lead to later loosening or damage:

• Too short anchor – the anchor expands in the adhesive mortar instead of in the brick. Solution: always measure the actual thickness of the tile + adhesive before selecting the anchor.
• Drilling with a hammer through the tile – the tile cracks immediately upon contact. Always turn off the hammer function when drilling through tiles.
• Drilling into a tile grout line – the grout line is the weakest spot, always drill into the center of the tile.
• Not tightening the anchor flush – the anchor must be fully embedded in the material, not protruding from the surface of the tile.
• Using galvanized screws in the bathroom – rust stains the tile and silicone seal. Always use stainless steel A2/A4.
• No silicone sealing around the hole – water during showering enters behind the tile, over time it undermines the adhesive and leads to tile detachment.
• Ignoring the direction of load – accessories mainly loaded in the vertical plane (towels, hooks) require different anchor dimensioning than accessories loaded horizontally (shelves).
• Installation on drywall without verifying the position of the profile – without hitting the metal C/U profile, the load capacity is minimal.

Additional installation vs. preparation during renovation

If you have the opportunity to renovate the bathroom from scratch or participate in the phase before tiling, take full advantage of it. Pre-embedding anchor bases (wood blocks, steel plates, dense fiberglass mesh in adhesive mortar) into the wall in advance will save you a huge amount of problems later. Plumbers and builders are usually willing to be reminded of this if you present them with a sketch showing the planned positions of the accessories.

If you are installing into a finished bathroom, it is always an advantage to have the original construction documentation available or at least know who carried out the construction and what materials were used. Slovak bathrooms from the 80s and 90s usually have full-brick masonry or concrete partitions – the gold standard for anchoring. New buildings from 2010–2025 often combine Porotherm with SDK partitions, which requires careful verification of the material before drilling.

You can clarify the choice of the right accessory, its dimensions and system compatibility in the articles What dimensions of towel holders and shelves do I need for my bathroom and System accessories vs. individual pieces: is it worth investing in a series like WallStoris?, where we compare different approaches to equipping a bathroom.

Care for anchoring after installation

Even a properly anchored accessory requires regular inspection. Once a year (ideally during autumn cleaning), check each accessory: gently shake the rod or bracket – if you feel movement or hear a clatter, it is time to tighten the screw or replace the loose anchor. Check the silicone seal around the brackets visually – cracked or discolored seals should be replaced as soon as possible to prevent moisture from getting behind the tiles. For more on maintaining accessory surfaces, see the article How to maintain and clean bathroom accessories made of stainless steel and painted surfaces.

Most frequently asked questions (FAQ)

What anchor to use if I don't know what is behind the tiles?

Start with tapping and a detector. If it is not clear, drill carefully and monitor the resistance during drilling: brick offers even, moderate resistance, concrete offers strong resistance, aerated concrete offers minimal resistance (quickly "disappears"), and a cavity – the drill bit suddenly drops into empty space. Choose the anchor accordingly – in case of uncertainty, the safest option is a chemical anchor, which works in any solid or hollow material.

Can I drill directly into the grout line between tiles?

Technically yes, the grout is a softer material (grouting compound), but this solution is not suitable for load-bearing anchoring. Grout has low mechanical strength and an anchor in it cannot support a permanent load. Always drill into the center of the tile. If you absolutely cannot do otherwise (e.g., the spacing of the anchor points of the accessory exactly falls on the grout line), choose an accessory with a different spacing or use anchor plates with distributed load.

How many kilograms can one anchor hold in brick masonry?

A standard plastic expansion anchor 6×50 mm in solid brick masonry can withstand a tensile load (directly from the wall) of 0.4–0.8 kN, which is 40–80 kg. In practice, however, for bathroom accessories, a bending moment (rod, shelf) is more common than pure tension, so I recommend not relying on the maximum and using at least 2 anchors per accessory with a safety factor of 4–5×. Heavier accessories (electric towel dryer, large shelf) should always be anchored at 3–4 points.

Why did my accessory start to loosen after one or two years?

There are several possible reasons: the anchor was set in the adhesive mortar instead of the brick (the mortar cracked over time), repeated load loosened the screw (use a screw with a central thread lock or a sealing washer), or moisture entered the drilled hole and the plaster lost its strength. Check the sealing every year, as described above.

Do I have to hit the stud when mounting into drywall?

For load-bearing anchoring (rod, towel dryer, shelf with load), yes, it is essential. For light decorative accessories (soap hook, small shelf up to 0.5 kg), a special hollow wall anchor (Toggler, Molly) is sufficient. Profiles CW/UW in drywall partitions are usually spaced 60 cm, or 40 cm. A metal detector will locate them in a few seconds.

Is it necessary to seal the hole with silicone during every installation?

Yes, always in the bathroom. In shower areas, near bathtubs and near sinks, it is an absolute necessity. In dry parts of the bathroom (e.g., a place for clothing hooks far from water), you can occasionally skip it, but silicone sealing is never harmful and costs less than later repairs to a wet wall tile. Always use sanitary silicone with an antimicrobial additive, not a universal one, which tends to mold over time.

Conclusion

Installation of bathroom accessories is a craft where details count twice as much as in standard installation. Correct identification of the wall, selection of an anchor suitable for the material and load, drilling with a special drill through the tiles, and thorough sealing with silicone – these are the steps that determine whether your accessories will safely and aesthetically serve you for decades, or whether in a year you will look at a fallen bracket and a cracked tile. Invest 30 minutes in preparation before each installation and the result will match the quality of the accessories you have chosen.

Do you have a question about this topic?

Struggling to decide or dealing with a specific situation in your home? Write to us – we are happy to help.

First and last name Do not fill in this field:

Email

Message