Step-by-step installation of a pre-wall mounting system
Wall-mounted installation system assembly step by step
The wall-mounted installation system is now standard in modern bathrooms – it hides water supply, drainage and the cistern behind the wall and allows the installation of a wall-hung toilet, which is easy to clean and visually lightens the space. Despite the fact that the final result looks simple, the actual installation has dozens of technical details that determine whether the entire system will work reliably for years, or whether leaks, noises or problems with the cistern will appear after some time. This article walks through the entire process from the beginning – from the preparation of the base, through the rough installation of the installation system, connection of water and drainage, embedding or plastering, to the final installation of the toilet bowl, seat and control button. It is suitable for experienced DIYers and craftsmen who are working with wall-mounted systems for the first time.
If you are not yet sure which type of system is suitable for your situation – whether it is embedding into brick masonry, installation into a drywall wall or renovation of an apartment core – please first take a look at our other articles in the Knowledge Center: How to choose a wall-mounted installation system: embedding, drywall or apartment core? or Differences between Renovmodul, Jadromodul and Sádromodul – which type is suitable for your bathroom?. This guide assumes that you have already chosen the type of system and we are going straight to the point.
Tools and materials you will need
Before starting the installation, prepare everything you will need during the work. Unnecessary interruptions due to missing tools unnecessarily prolong the time and increase the risk of errors. You will need the following tools:
- drill with hammer function (or a combination hammer) and a set of drill bits for concrete/brick
- angle grinder or wall router for cutting grooves in the wall (if embedding)
- spirit level (minimum 60 cm, ideally digital)
- measuring tape, pencil, ruler, string for measuring parallel lines
- screwdriver (cross and flat), set of wrenches (fixed and adjustable)
- plastic pipe cutter, thread tape (Teflon), silicone sealant
- mixer for mortar or cement-based sealant (for embedding)
- utility knife, scissors and insulating tape
In addition to the wall-mounted installation system itself, you will need the following materials: connecting hoses for water supply (usually ¾", flexible stainless steel), drainage pipes with a diameter of 110 mm and elbows according to the situation, screws and wall anchors suitable for the base, possibly construction foam sealant. Do not forget the finished finishing elements – control button for wall-mounted installation systems and the toilet seat, which you will install at the very end.
Step 1: Alignment and preparation of the work area
Correct alignment is the basis of the entire installation. Mounting the wall panel at a height where the toilet bowl will later be too low or too high is a mistake that can only be corrected by dismantling and reinstallation. The standard height of the sitting surface of a finished wall-hung toilet (including the toilet bowl) should be 400 – 420 mm from the floor to the top edge of the sitting surface. Most wall-mounted systems are adjustable in the range of 820 – 1000 mm measured from the floor to the top edge of the system, which corresponds to different cistern and bowl heights.
Important note: you always set the height from the finished floor, taking into account the height of the tiles and possible adhesive. If you have not yet laid the tiles, find out their planned thickness (typically 8–12 mm tiles + 5–8 mm adhesive = 13–20 mm) and subtract this value from the measured value. Mounting the system without considering the final floor is one of the most common mistakes on construction sites. More about dimensions and height adjustment can also be found in the article Dimensions and height adjustment of wall-mounted systems for wall-hung toilets.
Mark the centerline of the toilet (vertical axis of symmetry) on the wall with a pencil. This axis should be at least 400 mm from the side wall, ideally 450–500 mm, to ensure sufficient seating comfort. Then mark the installation height of the frame according to the chosen system. Do not forget to check where the existing water and electrical conduits run – especially during renovations, it is worth using a cable detector before drilling.
Step 2: Mounting the frame of the wall-mounted system
Most wall-mounted systems have a steel or galvanized frame with adjustable legs and anchoring consoles. The installation procedure depends on whether it is a system for embedding or for a drywall wall.
Installation of the embedded system
Systems such as Renovmodul – wall-mounted installation system for embedding, with tablet dispenser are designed for direct installation into brick or aerated concrete masonry. The frame has anchoring points for screws with wall anchors, or alternatively, the lower legs are embedded in the floor or fixed with cement-based sealant.
The procedure is as follows: First, place the frame on the marked location and set the height using the adjustable legs (telescopic adjustment). Check the level in two axes – vertical and horizontal – using a spirit level. Mark the positions of the anchoring holes on the wall, move the frame aside and drill the holes. Choose the diameter and depth of the holes according to the anchors supplied with the system, typically 8–10 mm diameter, depth 60–80 mm. Insert the anchors, place the frame back and screw it to the wall. Finally, check the vertical and horizontal alignment again – minor adjustments can be made by loosening the legs.
Installation of the system into a drywall partition
If it is a drywall (Gypsum Drywall, SDK) construction, the frame of the partition system is directly part of the load-bearing structure of the partition. The frame is anchored to the floor and ceiling (or to a side wall) using self-tapping screws or wall anchors. The metal substructure of the SDK partition (CW and UW profiles) is installed together with the installation frame, with the frame forming its core. This type of installation requires good spatial planning – the final thickness of the partition including the drywall sheet is typically 150–200 mm.
Step 3: Installation of the waste pipe
Always address the waste system before connecting the water supply – it is much harder to change the slope of the waste after the frame is fixed and covered. The waste pipe for a wall-hung toilet has a diameter of 110 mm and must have a minimum slope of 1.5 %, ideally 2 % (i.e. 2 cm drop per 1 meter of length). A greater slope is not always advantageous – with too steep a slope, water will drain away faster than solid waste can be flushed.
The waste opening of the partition system is located at the lower part of the frame, usually at a height of 220–240 mm from the floor (measured to the center axis of the waste opening). This opening is connected to an 110 mm HT pipe with an appropriate elbow (most commonly 87° or 45°, depending on the waste route). When embedded, the waste pipe runs in a groove in the floor or wall. In the case of an SDK partition, it runs in the space behind the drywall panel.
Key rule: the connection of the waste pipe must always be accessible or at least accessible via a maintenance opening. In practice, this means that you embed fixed joints (gaskets with adhesive), not push-fit joints without fixing. The waste opening in the partition system is designed to allow easy disconnection of the toilet bowl without the need for demolition – this is one of the main advantages of the partition system compared to traditional installation.
Do not forget to install the gasket (rubber sealing insert) into the waste opening of the system before embedding or covering. After the construction work is completed, access to the opening is limited and additional installation of the gasket becomes an unnecessary complication.
Step 4: Connecting the water supply and filling the cistern
The cistern of the partition system is supplied with cold water. The water supply is usually brought in from the wall at a level of 200–400 mm above the floor – a low-level supply is less visible and easier to hide. The cistern has an inlet valve (float or membrane type) with a connection of ½" or ¾". Between the distribution and the cistern inlet, it is essential to install a ball valve (shut-off valve), which allows servicing of the cistern without turning off the entire household water supply.
The connection from the valve to the cistern inlet is made using a flexible stainless steel hose with braiding, which is resistant to mechanical stress and minor structural movements. Tighten the hose with a wrench firmly, but carefully – over-tightening the plastic sealing can crack it and water may leak later. Do not use Teflon tape on threaded connections with a rubber gasket or sealing O-ring, only on metal threaded connections without sealing.
After connecting the water, fill the cistern and check the tightness of all connections. Set the water level in the cistern according to the manufacturer's recommendations – most cisterns allow setting the flush volume in two levels (large flush approx. 6 liters, small flush approx. 3 liters). Adjust the float so that the cistern fills to the correct level and the filling stops reliably – a filled cistern should not leak water into the toilet bowl even after several minutes of standing.
Step 5: Embedding or finishing the partition system
This is the phase in which the rough structure becomes the final partition. The procedure depends on the chosen system.
Embedding with brick or aerated concrete
With systems designed for embedding (e.g. Renovmodul), bricks or blocks are laid gradually around the frame, with the frame forming the load-bearing structure. Leave a free opening for the control button according to the dimensions in the technical documentation of the system – typically a rectangular opening of approx. 230 × 135 mm for a standard button. Be careful not to shift or dirty the inlet openings of the cistern and water supply with mortar during bricklaying.
Do the bricklaying in rows, checking each row with a spirit level. The mortar should be stiffer (not runny) – this will prevent the mortar from penetrating into the system frame. After bricklaying, let it harden for at least 24 hours before proceeding with further work (plastering, tiling).
Finishing with drywall
With an SDK partition, screw the drywall sheets (12.5 mm thickness for dry environments, 15 mm impregnated for wet environments) onto the metal substructure. Cut an opening for the button and also for the waste opening. Seal the joints between the sheets with caulk and sand them. Apply a base coat with a dispersion primer to the SDK surface before tiling.
Important: always use at least one row of impregnated sheets (green drywall) in the area where there is contact with water – behind the toilet bowl and around the water supply. In the bathroom, this rule usually applies to the entire area in most cases.
Step 6: Waterproofing and tiling
Before laying the tiles, waterproofing of the bathroom walls is necessary – at least in the area exposed to water (walls behind the toilet bowl and around it to a minimum height of 300 mm from the floor, in the case of a shower enclosure, all walls). Use certified sealing plaster (e.g. based on acrylic or cement plaster) applied with a roller in two layers. Use sealing tapes at corners and transitions to prevent water from entering the joints.
Tiling starts from a horizontal line (so-called base) to avoid small cut pieces on visible areas. Leave an opening for the button exactly according to the dimensions of the chosen control button in the area of the partition system. Cut the tiles with a sharp ceramic cutter or an angle grinder with a ceramic disc.
Step 7: Final installation of the toilet bowl
After the tile has dried and the joints have set, it is time to install the toilet bowl. Two steel threaded rods (supporting screws, M12) protrude from the false wall system – plastic caps, rubber spacing washers, and finally the toilet bowl itself are slipped onto them. The exact gap between the toilet bowl and the wall depends on the depth of the bowl and the thickness of the false wall – typically 20–30 mm.
Before fitting the bowl, insert the waste collar (rubber sealing insert) into the neck of the false wall system – if you have not done this earlier. Carefully place the bowl onto the threaded rods and insert the waste neck into the collar. The collar must be inserted at least 40 mm deep and centered – a skewed position will cause a leak. Then tighten the nuts on the threaded rods, but carefully – porcelain is fragile and excessive tightening may cause it to crack. Use plastic washers between the nut and the porcelain.
Finally, check that the bowl is level (using a spirit level on the seating surface), that it is not movable, and that the waste neck fits tightly.
Step 8: Installation of the toilet seat and control button
The toilet seat is mounted on the final screw caps of the toilet bowl. Modern seats with a Softclose function prevent the lid from slamming shut – this is a detail you will appreciate especially during night use. You can choose, for example, Toilet seat SOFTCLOSE, Duroplast or Toilet seat with slow closing SOFTCLOSE, Duroplast, white. Both types are made of durable duroplast, which is harder and more resistant to chemicals than regular plastic. For applications with non-standard bowl geometry, it is suitable to use Universal toilet seat with integrated insert, Duroplast, which covers a wider range of screw cap spacing.
Mount the flush control button into the prepared opening in the tiling. Most buttons are designed for a standard false wall thickness of 90–120 mm and are height-adjustable within this range using telescopic guides. Control button for false wall installation systems in white finish is suitable for most standard false wall systems and blends in with the white tiling. The button is inserted into the opening and fixed with spring-loaded fasteners – without screws. Adjust the length of the control rods (included with the button) so that the activation button sits flush with the surface of the tiling.
Step 9: Pressure test and first flush
Before the first flush test, check all water connections again. Open the water supply slowly and let the cistern fill. While filling, monitor the water supply connection and the float valve connection inside the cistern. After the cistern is filled, let the flushing system sit for 5–10 minutes and check for any leaks.
Perform the first flush with the space under the toilet bowl open – you want to see if the waste collar seals properly and if water is not leaking from the waste connection. If the water level in the bowl stops rising after the flush (the cistern refills and closes), the system is working correctly. If water continues to flow into the bowl after the cistern is filled, there is a problem with the float rubber or the float position – both can be adjusted without breaking anything, through the opening for the control button or the top service cover of the cistern.
Common mistakes during the installation of false wall systems and how to avoid them
From the experience of dozens of installations, we know that most problems stem from a few recurring mistakes:
- Incorrect installation height: The most common mistake – the system is installed without considering the thickness of the final floor (tiles + adhesive). Result: the toilet bowl is too low or too high. Always measure from the final finished floor.
- Insufficient slope of the waste pipe: A slope less than 1.5% causes sludge to settle in the pipe and future clogs. For a short waste pipe (up to 1 m), a slight slope is sufficient, but for longer pipes, you must strictly adhere to the slope.
- Missing ball valve on the water supply: Without a shut-off valve on the false wall, you must stop the water supply for the entire apartment during every service. In practice, this causes people to delay maintenance, and a minor issue turns into a major one.
- Over-tightening the toilet bowl: Porcelain cracks if the nuts are tightened without plastic washers or too tightly. The correct force – by hand + wrench only slightly – is sufficient.
- Missing waterproofing: Moisture accumulates behind the false wall and, over years, penetrates the structure. Waterproofing behind the toilet bowl is a necessity, not a luxury.
- Incorrect position of the button opening: You cut the opening too early, and then it turns out the button does not fit the tiling. Always measure according to the specific button before cutting the tiling.
Practical scenarios from real customer cases
Renovation of an apartment core (panel building): In old panel buildings, it is typical that the original toilet is directly next to the stack and the waste has minimal space for routing. Here, a system with a low waste neck position (220 mm from the floor) and an 87° elbow, which maintains the slope even on a short section, proves effective. The frame is anchored into the reinforced concrete wall and floor – here, it is important to use the correct types of anchors (expanding in concrete, not plastic spiral ones).
New construction – gypsum board false wall: In new constructions, the most common scenario is a false wall with drywall cladding. Advantage: the false wall frame is easy to anchor, the electrical wiring is routed in the false wall space, and the water supply and waste can be conveniently planned before plastering. Disadvantage: later, you cannot easily expand the false wall – everything must be well planned in advance (width of the false wall, seating height, electrical layout).
Second WC in the technical room: Here we face the question of whether the system can be connected to the existing waste and water. If the existing waste pipe is within a feasible distance (up to 3 m) and has a free trap, the installation is straightforward. If not, you will either need to install a new waste pipe or consider a pumping station solution for the WC – a front wall system with a pump, however, is a special category.
If you are looking for more detailed information on which type of front wall system is suitable for a specific situation, we also recommend reading the article Front wall system for built-in vs. drywall – what to choose or Flushed or front wall system: which type to choose in the Knowledge Centre.
Most frequently asked questions (FAQ)
Can I install a front wall system myself, without a plumber?
Mounting the frame, embedding and tiling can be handled by a skilled DIY enthusiast. However, connecting to the water supply and waste in many cases requires plumbing knowledge – incorrect connections can cause leaks, property damage and void insurance. At the very least, we recommend consulting or having assistance from an experienced plumber during the pressure test and first start-up.
What is the typical depth of a front wall system?
The standard depth (thickness of the front wall from the wall to the surface of the tiling) is 150–200 mm for SDK front walls and 120–150 mm for embedded systems. It depends on the specific system and the way the waste pipe is routed. More detailed information can be found in the article What is the correct height and size of a front wall system for a standard bathroom.
What if water keeps running into the bowl after installation?
The most common cause is a worn or improperly adjusted float valve (membrane or ball). Servicing is possible without breaking the wall: simply remove the control button and replace the valve membrane through the opening in the front wall. If the issue is with the float position, it can be adjusted by turning the regulating screw. The procedure should be described in the service manual of your system.
Is it possible to later replace the WC bowl without breaking the front wall?
Yes, this is one of the key advantages of a front wall system. The WC bowl is attached only to two threaded rods with nuts and inserted into the trap through the waste opening. By unscrewing the nuts, pulling the bowl out of the trap and disconnecting the bidet or other connections (if any), you can remove the bowl. A new bowl is installed in the reverse order – it is important that it has the same spacing of the mounting holes (standard: 180 mm).
What is the correct flushing volume for a standard WC?
Modern cisterns allow for a two-stage flush: small 3 litres (short button press) and large 6 litres (long button press). The volume is adjustable within a range of about 3–8 litres depending on the manufacturer. From a water consumption perspective, the recommended volume is 6/3 litres according to EN 997. Some systems allow for an even smaller flush of 2 litres, but with insufficient slope of the waste pipe, this can cause drainage problems.
Can I later add a bidet spray or a WC with hygienic cleaning to a front wall system?
Yes, provided you have prepared a cold (or possibly also hot) water connection near the WC bowl during installation. Some front wall systems have a built-in outlet for a bidet or hygienic spray set. If you did not prepare the connection in advance, it is technically possible, but you will need to open the front wall or run the connection on the surface – which is a less elegant solution. Therefore, it is worth considering this option in advance, before embedding or tiling.
Conclusion
Installation of a front wall plumbing system is a project that requires precision at every step – from the initial height alignment to the final tightening of the control button. An error in an early stage will usually become apparent much later and its removal will require extensive demolition work. On the other hand, a well-planned and carefully executed installation will give you a reliable, hygienic and aesthetically clean installation that will function without problems for decades.
If you are looking for a specific system suitable for your conditions, take a look at the range in the category front wall installation systems on atria.sk, where you will find systems for embedding and drywall in various configurations including practical accessories such as tablet dispensers, control buttons and seats with soft closing.
Do you have a question about this topic?
Not sure or dealing with a specific situation in your home? Write to us – we are happy to help.