Step-by-step installation of multi-layer pipe: tools, process, errors

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Installation of multilayer pipe step by step: tools, procedure, mistakes

Multilayer pipe has become a standard in domestic water and heating distribution systems over the past twenty years. It is no coincidence – it combines the flexibility of plastic with the rigidity of aluminum, retains its shape after bending, does not corrode, does not impart taste or odor to water, and with proper installation will last for decades without problems. The key phrase here is "with proper procedure." From practice, I know that most faults – leaks, cracked fittings, bulging insulation, noisy pipelines – do not come from poor material, but from avoidable mistakes. This article will guide you through the entire installation process from tools through individual steps to checking the completed pipeline, including those mistakes I repeatedly see at customer sites.

If you are still considering which type of pipe to use, I recommend reading the article How to choose pipe for potable water distribution: multilayer vs. copper vs. plastic or Multilayer pipe vs. HEPWORTH: which is better for your distribution. Here we assume you have already decided on a multilayer solution and go directly to the installation.

Construction of multilayer pipe: what you are actually installing

Before reaching for the tools, it is worth understanding what the pipe is made of. Multilayer (multilayer, PE-AL-PE or PE-Xb/AL/PE-Xb) pipe consists of five layers: an inner layer of polyethylene (PE or cross-linked PE-X), an adhesive layer, an aluminum sheath, another adhesive layer, and an outer protective PE layer. This structure gives the pipe its properties – aluminum prevents oxygen diffusion, retains shape after bending and reduces linear expansion, while the plastic layers ensure a smooth inner surface without deposits and resistance to corrosion.

For common domestic water distribution, the following dimensions are most frequently used:

16×2 mm – branches to individual outlets (basin, WC, shower), maximum recommended branch length about 8–10 m with a single draw-off
18×2 mm – stronger branches, combined distribution, sometimes also the main distribution in a smaller apartment
20×2 mm – main horizontal distribution, connection of several draw-offs in sequence, larger houses

For comparison and to choose the correct diameter, I also recommend reading the article What pipe diameter do I need for domestic water distribution and Dimensioning pipe for potable water: how to calculate diameter and length.

Tools and accessories: what you really need

This is the area where amateur and professional differ the most. Not in knowledge – but in tools. Multilayer pipe can be installed with a pressing or compression system. Each type of fitting requires different tools. Do not mix them – pressing pliers for PRESS fittings are different from pliers for compression fittings.

Basic toolset for pressing (PRESS)

Battery-powered pressing pliers (e.g. Rems, Novopress, Virax) with jaws corresponding to the pipe diameter (16, 18, 20 mm) – this is the most important tool and is not cheap; renting is a fully legitimate option for a one-time job
Pipe cutter – rotating, specifically for multilayer pipe; a standard copper pipe cutter can deform the AL layer
Caliper + beveler (or combined tool) – for aligning the cut into a circle and reducing the inner edge
Expander – only for systems with an expansion head (e.g. Uponor, Rehau); not needed for compression or standard PRESS fittings
Measuring tape or retractable tape measure
Marker or pencil for marking on the pipe
Bender (spring or pulley) – for curves smaller than 8× outer diameter
Level – for horizontal pipelines
Drill, possibly a hammer drill for anchors and grooves
Sealing tape or sealing compound – only for threaded transitions, not on the pipe itself

For compression fittings

If you use compression fittings (threaded, with a nut), you do not need pressing pliers. Instead, a strong wrench (usually two sizes) is sufficient, but you still need a quality pipe cutter, caliper and beveler. Compression fittings are more tolerant of imperfect cuts, but more prone to loosening due to vibrations or temperature changes.

Pipe preparation: the first step that must not be underestimated

Pipe preparation is neglected by almost every beginner and part of experienced installers. It is the first and most important step of the entire installation.

Measuring and marking

Multilayer pipe is delivered in coils – for example IVAR Turatec 16×2 in a 200 m coil or IVAR Turatec 20×2 in a 100 m coil. Always measure the actual route with a reserve before cutting: add the insertion depth into the fittings (typically 12–22 mm on each side, depending on the fitting manufacturer and dimension), and possible arc lengths. For routes longer than 5 m, also consider expansion – the pipe expands when the water heats up, typically 0.025 mm/m/°C for PE-Xb/AL. With a temperature difference of 50 °C and a length of 10 m, this is 12.5 mm of expansion – this must be absorbed by an expansion arc or compensator, otherwise the pipe will bend and create stress on the fittings.

Cutting

Cut the pipe only with a rotary cutter for multilayer pipe, perpendicular to the axis. Check the right angle – a slanted cut will cause the pipe to not fit symmetrically in the fitting, the sealing is unevenly loaded and leakage is possible. After cutting, check that the cut is not deformed – coiled pipe tends to slightly flatten when cutting, if the cutter jaws are not sharp or if you cut slowly.

Calibration and edge alignment

This is the step where beginners make the most mistakes – they skip it. After cutting, the pipe has a slightly flattened cross-section and a sharp inner edge. A calibrator (a round mandrel of the correct diameter) rounds the pipe back to its original circle. An edge trimmer trims the inner edge – without it, you risk scratching the fitting seal when pushing the fitting into the pipe.

The entire process of pipe end preparation looks like this:

Measuring and marking the cut location
Cutting with a rotary cutter (perpendicular, evenly, in one smooth motion)
Calibration – inserting the calibrator and turning it 2–3 times firmly
Edge alignment – inserting the edge trimmer and turning it
Visual inspection – the cross-section must be round, without notches and without a sharp edge

Bending the pipe: limits and practice

One of the advantages of multilayer pipe is the possibility of bending directly on the route without elbows. The aluminum layer holds the shape after bending – the pipe does not return to its original position. However, there are rules:

Minimum bending radius: for 16×2 it is about 65–80 mm, for 20×2 about 80–100 mm. Most manufacturers specify a minimum of 5× the outer diameter for manual bending, 3.5× when using a bender.
Spring bender: inserted into the pipe, the pipe is smoothly bent to the desired angle, then the spring is pulled out. Suitable for arcs up to 90°.
Pulley bender: more precise, suitable for repeated bends, professional use.
Never bend a sharp angle without a bender – the aluminum will fold, the inner diameter will narrow and a permanent fatigue point will be created in the material, where the pipe can eventually break.
Do not press the pipe by hand into a wall or strip without a bender – even a shallow bend without a tool can create an uneven flattening.

Fitting installation: PRESS system step by step

PRESS fittings (crimped, non-removable) are standard in professional installation. The procedure is as follows:

Mounting the sleeve (crimp ring): before inserting the fitting, slide the crimp sleeve onto the end of the pipe – this is part of the fitting kit. This is surprisingly often forgotten, and after inserting the fitting, it is not possible to correct it without cutting the pipe.
Inserting the fitting: push the fitting firmly into the prepared end of the pipe until it reaches the stop. On the pipe, you should see that the pipe reaches at least the stop on the fitting (some fittings have a visible control mark or a transparent window on the body). Push the fitting clearly – if it does not go in easily, check whether you have properly aligned the edge and calibrated the pipe.
Sliding the sleeve: slide the sleeve along the pipe so that it covers the crimp zone of the fitting.
Crimping: attach the crimping pliers of the correct size (e.g. jaws for 16, 18 or 20 mm), make sure the jaws are perpendicular to the pipe axis and in the correct position (the jaws must fit exactly on the sleeve). Press the pliers to the end of the cycle – most battery-powered pliers stop automatically after completing the crimping cycle. An incomplete crimping cycle is dangerous – the joint looks OK, but is not crimped to full pressure.
Inspection: visually check that the crimping is symmetrical (no overhang on one side), and that a control ridge or deformation of the sleeve corresponding to the crimping is visible.

Compression fittings: installation procedure

With compression (screwed) fittings, the procedure is simpler in terms of tools, but precision is equally important:

Disassemble the fitting: unscrew the lock nut and remove the sealing and locking ring.
Slide the nut onto the pipe (screwed end outwards), then the sealing and locking ring.
Push the body of the fitting firmly into the pipe until it reaches the stop.
Slide the sealing and ring towards the body of the fitting and screw the nut by hand, then tighten with a wrench – typically 1 to 1.5 turns after hand tightening. Over-tightening is just as bad as under-tightening – a broken fitting due to excessive torque is a common mistake.

Pipe Fixing: Clamps, Spacings, Expansion

Pipe fixing determines whether the piping system will be quiet, stable, and expansion-safe. Guidelines:

Clamp spacing: for horizontal piping 16×2 maximum 500 mm, for 20×2 maximum 600 mm. For vertical piping, you can slightly increase the spacing, but not by more than 20 %.
Fixed vs. sliding clamp: each pipe section must have at least one fixed clamp (prevents expansion movement), the rest are sliding (allow movement along the axis). Always use a fixed clamp at fittings and elbows.
Expansion loops: for long straight runs (over 3–4 m), install an expansion loop or compensator. Rule of thumb for approximate calculation: length of loop arm (in mm) = 33 × square root of (outer diameter in mm × length of the expanding section in mm). For 20 mm pipe and 6 m section: 33 × √(20 × 6000) = 33 × 346 ≈ 11 400 mm → loop arm at least 115 mm.
Insulation: thermal insulation is mandatory for hot potable water, vapor barrier insulation is required for cold water in humid areas (otherwise condensation on the pipe surface). Insulation is installed before fixing, not after.

Pressure classes and temperatures: what affects installation

Multilayer pipe from the range is marked with PN10 and temperature +70 °C or +95 °C. What does this mean for installation?

PN10, T=+70 °C: pressure 10 bar at temperature 70 °C. This is a standard solution for cold potable water and hot utility water systems. The pressure in the household water supply is typically 2–4 bar, so the safety margin is significant.
PN10, T=+95 °C: suitable also for connection to storage heaters with higher temperature or combined water/central heating systems. This class does not require different tools or installation procedure.

For a detailed explanation of pressure classes, I recommend reading the article Pressure classes PN10 and temperatures +70°C vs. +95°C: what they mean for your piping system.

For specific products: IVAR Turatec 18×2 in a 200-meter roll is a popular choice for medium-sized apartment and house systems, where cost per meter is not the main concern, but long-term reliability and the ability to lay longer branches without fittings is.

Pipe routing: wall vs. floor vs. installation channel

Multilayer pipe can be routed in several ways:

Slot in the wall (masonry)

The pipe is laid into a chiseled or cut slot, which is then filled after installation and pressure test. The slot must be at least 10 mm wider and deeper than the pipe diameter including insulation. The pipe must be free in the slot – do not embed it without insulation and without space for expansion. A protective sleeve is recommended in areas where the pipe crosses a ceiling, floor, or other structure.

Floor – system in anhydrite or concrete

Common in underfloor heating, but can also be used for potable water systems. The pipe is laid on a thermal insulation board, fixed with plastic ties, and poured with self-leveling compound. In this case, expansion is handled by the loops of the system. The pipe must be in a protective sleeve at least at the points where it crosses expansion joints in the slab.

Installation channel / shaft

For vertical risers, accessible manifolds, and areas where future service is needed. The pipe hangs from clamps fixed in the shaft, insulation is installed before fixing. Advantage: in case of failure, there is access to the pipe without demolition.

Pressure test: mandatory step before covering

Pressure test is a legal requirement for potable water systems and at the same time the most valuable step in installation. Never close slots, screeds, or finishes before the pressure test.

Pressure test procedure

Close all outlet valves (taps at outlets).
Connect a manual pressure pump (pressure gauge) to the system.
Fill the system with water and bleed air – at the highest points of the system there should be bleed valves or at least removable fittings through which air can escape.
Increase pressure to 1.5 times the operating pressure, maximum 6 bar for PN10. A standard test is at 6 bar.
Let the pressure stabilize for 30 minutes – temperature drop and material settle.
Read the pressure. A drop of more than 0.2 bar during 30 minutes indicates a leak. Immediately find the leak location – visually (water traces, drops) or by listening (sounds of flowing water).
After a successful test, record the result (date, pressure, duration) and photograph the system before covering.

From practice: most leaks during pressure test appear exactly at fittings, where the crimp sleeve was forgotten to be pushed before inserting the fitting. It is an error that cannot be fixed – the entire fitting must be cut out and remade.

Most common mistakes when installing multilayer pipe

Over years of contract work I have seen the same mistakes repeated. Here they are listed from the most common to the less common:

Mistake #1: Omitting the calibrator and straightener. Result: leak at the fitting, damaged sealing ring.
Mistake #2: Forgetting to push the crimp sleeve before inserting the fitting. Result: need to cut the section and remount the fitting.
Mistake #3: Incomplete crimping cycle – crimping stopped before the pliers finish the cycle. Result: the joint looks OK, but leaks during pressure test or later in operation.
Mistake #4: Mixing fittings from different manufacturers. Crimping geometry differs among manufacturers – a fitting from manufacturer A must not be crimped with pliers from manufacturer B, even if they look the same visually.
Mistake #5: Bending without a pipe bender. Result: aluminum layer folding, permanent flattening, reduced flow, fatigue cracks over time.
Mistake #6: Too large clamp spacing. Result: the pipe sways during expansion, hardens against the structure when heated, causing noise (clicking, cracking).
Mistake #7: Lack of expansion loops on long straight runs. Result: the pipe expands when heated and creates stress on fittings or sways at clamps.
Mistake #8: Using the wrong cutting tool – e.g., metal saw or ordinary copper cutter. Result: aluminum chips in the pipe, deformed cut, poor sealing surface.
Mistake #9: Installation without pressure test or before covering. Result: leak discovered after years – wet wall, damage to the building.
Mistake #10: Installing insulation after fixing. Result: incomplete insulation at clamp points, condensation or thermal bridges.

Specifications for combined water + heating distribution

Multi-layer pipe is used in practice for both distribution systems in one house. If you do this, ensure clear color differentiation of the pipe or routes (red clamps / insulation = heating, blue = cold water, red = hot water). Never mix fittings certified only for water with fittings for heating without verifying the manufacturer's certification. Pipes certified for potable water must meet hygiene standards – see the article Hygiene and material safety of potable water pipes: what you need to know.

HEPWORTH pipe as an alternative: different installation method

If you are considering copper pipe instead of multi-layer pipe, the installation is fundamentally different. HEPWORTH 15 mm or HEPWORTH 22 mm are joined by soldering (soft solder) or pressing (PRESS brass or stainless steel fittings). Bending is more difficult with copper – without a bender and without filling with sand (for soft copper) there is a risk of pipe wall collapse. Details can be found in the article Installation of HEPWORTH copper pipe: soldering or pressing.

For a comparison of both materials in terms of installation, durability and price, I recommend reading Multi-layer pipe vs. HEPWORTH: which is better for your distribution.

Most frequently asked questions (FAQ)

Can I cut multi-layer pipe with a standard copper pipe cutter?

This is not recommended. Standard copper pipe cutters have blades optimized for a softer material and tend to deform the aluminum layer of multi-layer pipe during slow or hard cutting. The result is an oval cut, which may not be perfectly round even after calibration. A proper rotational cutter for multi-layer pipe has a special blade geometry and side rollers that prevent deformation – investing in the right tool is worthwhile.

How long do press fittings last? Is PRESS really forever?

Press (PRESS) fittings are designed for a service life of 50 years under continuous operation when installed correctly. The key is "when installed correctly" – a complete pressing cycle, correct jaws, correct sleeve, calibrated pipe. Practical experience: a properly pressed joint usually outlives the pipe itself. An incompletely pressed joint may fail during pressure testing or in the first season.

How do I know if my pressing cycle is complete?

Modern battery-powered pressing pliers have an indicator of cycle completion – an audio signal, a light indicator or a mechanical stop. If your pliers do not have such indicators (older models), you must check whether the jaws have fully closed to the stop. A visible sign is the shape of the sleeve after pressing – it must be evenly deformed around the entire circumference matching the jaw profile. Any partial deformation (only on one side) indicates that the cycle was interrupted.

Do I need to perform a pressure test for a simple bathroom renovation?

Technically and legislatively yes – every new or renovated potable water distribution should undergo a pressure test before being covered. In practice, for small jobs (e.g. replacing one tap or a connection to a sink), most tradespeople do not formally address this – but at least visually check the tightness with the main shut-off closed and at maximum network pressure for at least 15 minutes. If it is a new distribution running in grooves that will be embedded, a pressure test is not just a recommendation – it is insurance against expensive damage.

Can I embed multi-layer pipe in the wall without a protective sleeve?

Technically it is possible for cold water and short straight sections if the pipe is wrapped in insulation and the groove is sufficiently spacious to allow free movement during expansion. For hot water or long sections, a corrugated sleeve is strongly recommended – it allows longitudinal pipe movement during expansion without friction against the masonry. In areas passing through ceilings or floors, a protective sleeve is always mandatory to prevent contact with concrete elements and to allow possible replacement without demolition.

What is the difference between 16×2 and 20×2 pipe for home distribution? When to use which?

The numbers mean outer diameter × wall thickness, so the inner diameter of 16×2 is 12 mm and 20×2 is 16 mm. For branches to individual outlets (WC, sink, shower), 16×2 is sufficient for a branch length of up to 8–10 m and one outlet in sequence. For main horizontal distributions supplying multiple outlets in sequence or for lengths over 10 m, 20×2 is more suitable. Proper sizing is a more extensive topic – see the article Sizing potable water pipe: how to calculate diameter and length and What pipe diameter do I need for home water distribution.

Conclusion: practice makes perfect, but rules make the distribution reliable

Installation of multi-layer pipe is not rocket science, but it requires diligence. Each step – cutting, calibration, alignment, sleeve placement, fitting insertion, pressing, fastening, pressure testing – has its justification and skipping any of them can show up immediately or years later. Quality material is the foundation: pipe such as IVAR Turatec 16×2 will give you the necessary confidence in material properties, but the quality of the distribution also depends on the work on site. Invest in the right tools, take time for each connection and do not forget the pressure test – these are three decisions that make a 50-year distribution instead of a problematic 5-year one.

If you are dealing with faults or leaks in an existing distribution, I recommend reading the article Common faults and leaks in potable water pipes: causes and solutions. For more general questions about pipe, I recommend Common questions about potable water pipe distribution.

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.