🛡️ The Protective "Corrugated Sleeve"
Water pipes (PEX or Multilayer) are strictly forbidden from touching the concrete bare. They must always run inside a corrugated protective sleeve (red for hot, blue for cold). This sleeve does three things:
Network Routing in New Buildings: Where Pipes Go and What to Watch Out For with Electrical Wiring
Mapping the piping in a new building (or a major renovation) is like designing the traffic plan of a large city. Water (plumbing, heating, drainage) must travel from the central boiler room or manifold to every room - quickly, safely and… completely invisibly.
Incorrect routing does not simply create aesthetic issues. It can damage the structural frame (the reinforced concrete), cause water pressure drops, or create potentially lethal hazards if it crosses electrical wiring incorrectly.
Let us look at the 3 main "routes" engineers use to conceal networks and the non-negotiable installation rules.
1. Floor Routing: The "Classic" Network
The most common path for radiator, underfloor heating and plumbing pipes is on the concrete slab, before the insulating lightweight concrete fill (or screed) and tiles are laid.
1️⃣ Protection During Concreting
It protects the pipe from gravel and shovels during the concrete pour, preventing accidental puncture or crushing.
2️⃣ Thermal Expansion Space
It creates an air gap that allows the pipe to expand ("stretch") when hot water flows through, without breaking its supports inside the concrete.
3️⃣ Theoretical Replacement
It theoretically allows the pipe to be replaced if punctured, by pulling it through. In practice, however, this requires a great deal of luck, especially over long runs.
📐 No Diagonal Routes
Pipes must run parallel or perpendicular to walls. Arbitrary diagonals ("taking a shortcut through the middle of the living room") make future detection impossible. If you ever need to drill the floor to fix a door stopper, you risk puncturing the pipe.
2. False Ceiling Routing: The Modern Solution
In modern homes and office buildings that use concealed fan coils or ventilation systems (HRV/ERV), the floor alone is not enough. Here, the pipes "fly" and hide inside the plasterboard ceiling.
🔧 Hangers & Supports
Pipes full of water are extremely heavy. They must be supported with metal hangers (rubber-lined clamps) on the ceiling slab, every 1 to 1.5 metres, to prevent sagging and vibration.
🛡️ Perfect Insulation
As we discussed in the previous article, if a chilled-water pipe in the false ceiling is not insulated perfectly with Armaflex, the "sweat" (condensation) will destroy the plasterboard and breed mould.
📐 Slopes
Pipes must maintain a slight gradient to prevent air becoming trapped at high points. Trapped air (bubbles) blocks water circulation, creates noise and reduces system efficiency.
3. Wall Routing: The "Chases" and Building Safety
To bring water up from the floor to the sink or shower tap, the plumber must chase (cut a channel into) the wall.
⚠️ Chasing Concrete Is Forbidden
The plumber may chase brickwork, but is strictly forbidden from cutting deep into ("wounding") the reinforced concrete columns and beams of the building, especially horizontally. If the reinforcing bars of a column are cut to pass a pipe, the entire house's earthquake resistance is compromised!
📐 Vertical Runs Only
Wall chases must be strictly vertical from floor level up to the tap. This way, you know in the future that "above or below the tap, I must not hammer a nail for a picture frame because a pipe runs there".
4. The "Battle" of the Trades: Crossings with Electrical Wiring
On the floor of a new home, water pipes will inevitably cross paths with electrical conduits. Strict safety rules apply here.
1️⃣ Water ALWAYS Goes Below Power
When water and power conduits must cross on the floor (one above the other), the water pipe must pass underneath. If a leak ever occurs, the water flows downward (gravity) and does not pool on the electrical cables.
2️⃣ Safety Clearances
If they run parallel in the same wall, they must maintain a clearance of at least 10–15 centimetres between them.
3️⃣ The Golden Rule of Distribution Boards
It is strictly forbidden for water or drainage pipes to run directly above or directly behind the main electrical distribution board. If even a single drop reaches the circuit breakers, the fire or electrocution risk is enormous.
5. Summary: The Invisible Map Behind the Walls
📋 What to Remember
Pipe routing is the invisible "backbone" of the house. Do not let work crews cut random shortcuts. Make sure to take plenty of photographs of all floors and walls BEFORE concrete is poured and plaster is applied. This "photographic archive" will prove invaluable in the future.
➡️ Next Step
Now that we have routed the pipes, we reach the most critical moment of the installation: How do we join them without worrying about leaks? Get ready for the next article: Pipe Connections (Press-fit, Brazing, Compression). What are the techniques and why are "concealed" joints under the floor considered a plumbing crime?
Related Articles
Copper, PEX or Multilayer? Comparative Piping Guide Pipe Insulation (Armaflex): Correct Thickness & Preventing Condensation Pipe Connections: Press-Fit, Brazing or Compression? Pressure Testing (Pressurisation): Pre-Concrete Guide
Hydraulic Networks & Energy Distribution
Return to category.
Go to categoryCentral Guide
Return to the central guide.
Go to guide