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← All systems
Technical sheet
A.01A.02
SystemS-09

Screed radiant floor

A floor build-up in which a coil of pipes, embedded in the screed, turns the whole floor into a large low-temperature heat emitter. The heat rises by radiation, even and silent; the same system can cool in summer. Below, a studded insulation panel directs the heat upward and holds the pipes.

PavimentazioneEmbedded underfloor heating/cooling
B.01
System build-up6 layers
CALORE → AMBIENTE1. Pavimentazione2. Massetto radiante3. Tubi (acqua 30-40 °C)4. Pannello bugnato6. Solaio

Technical section of the system, from inside (left) to outside (right).

Embedded underfloor heating/cooling
Temperatura di mandata
30-40°C
Passo della serpentina
10-20cm
Spessore sopra i tubi
≥ 3cm
Resa termica (risc.)
≈ 60-100W/m²
Diametro tubi
16-20mm
Raffrescamento
sì (con deumidif.)
Descriptive memo

A floor build-up in which a coil of pipes, embedded in the screed, turns the whole floor into a large low-temperature heat emitter. The heat rises by radiation, even and silent; the same system can cool in summer. Below, a studded insulation panel directs the heat upward and holds the pipes.

The radiant floor replaces the local heat emitters (radiators) with an extended, mild surface: the whole floor. A network of pipes embedded in the screed circulates low-temperature water (30-40 °C), and the floor releases heat by radiation upward. The result is even comfort, with no air movement or raised dust, and excellent performance with renewable sources.

Low temperature and heat pumps

The energy advantage comes from the large radiant surface: to heat a room, water only a little warmer than the air is enough (30-40 °C against the 60-70 °C of a radiator). This low temperature is the ideal regime for heat pumps and solar systems, which perform far better when they have to produce warm rather than hot water. The floor also stores heat in its mass and releases it gently, damping the swings.

Inertia: a virtue and a constraint to manage

The mass of the screed is both the strength and the limit of the system. On one hand it stabilises the temperature and lets one exploit tariffs and the sun; on the other it makes the system slow to respond: rapid on/off has no effect, and the control must be set on weather-compensated logic and anticipation. Screed thickness, cover over the pipes and coil pitch must be balanced to combine good output with manageable inertia.

Cooling and condensation: the summer limit

By circulating cool water (16-18 °C), the same floor can cool in summer. But here a physical limit appears: if the surface falls below the dew point of the indoor air, condensation forms on it, slippery and harmful. For this reason radiant cooling always requires humidity control (dehumidification) and a control strategy that keeps the floor temperature above the dew point. The cooling output is therefore more limited than the heating one.

At a glance

Composition

6 layers · 3 materials · 1 processes

Strengths

  • Even, silent comfort with no dust
  • Low temperature: ideal for heat pumps and solar
  • No wall emitters: freedom of layout
  • Reversible: can cool in summer

Execution specs

Flow temperature
30-40 °C
Coil pitch
10-20 cm (tighter at edges)
Cover over the pipes
≥ 3 cm
Perimeter band
compressible, continuous
Pressure test
before and during the pour

Normative references

UNI EN 1264 (risc. a pavimento)UNI EN ISO 11855 (sistemi radianti)UNI EN 13813 (massetti)D.M. 26/06/2015 — Requisiti minimiD.P.C.M. 05/12/1997 (acustica)D.P.R. 380/2001
Systems architecture

Why it works

Low temperature · large surface
30-40 °C · evenradiant floor70 °C · spotradiator

The whole floor becomes the emitter: a huge surface releases heat by radiation with barely warm water (30-40 °C), against the 60-70 °C of a radiator. This low temperature is the ideal regime for heat pumps and solar; the mass of the screed, however, makes the system inert and slow to control.

Flow temperature of the emitters

Comparison · insulants
Radiant floor
≈ 35 °C
Fan coils
≈ 45 °C
Low-temp radiators
≈ 55 °C
Traditional radiators
≈ 70 °C

Shorter bar = cooler water = more output from the heat pump (COP) and solar. The radiant floor is the lowest-temperature emitter, ideal for renewables.

Nodal details

Critical junctions · sections
123456
D.01
Perimeter edge band

The radiant screed expands as it heats: a compressible band isolates it from walls and columns, avoiding thrust and cracks. The band is turned up above the floor finish and then trimmed.

  1. Wall
  2. Edge band (expansion)
  3. Radiant screed
  4. Pipe
  5. Studded panel
  6. Floor finish
12345
D.02
Manifold and circuit

From the manifold (flow and return) the serpentine circuits start, with a tighter pitch in the cold perimeter zones. The bends have a minimum radius so as not to pinch the pipe; vents and valves regulate and balance.

  1. Manifold (flow/return)
  2. Serpentine circuit
  3. Pipe pitch
  4. Minimum-radius bends
  5. Vents and valves

Installation controls

Specification · checklist

01 · Insulation laying

Continuous studded panel, interlocked
Full-height perimeter band
Vapour barrier where required

02 · Pipework

Design pitch, tighter at the perimeter
Minimum bend radius respected
Pipes clipped to the studs

03 · Manifolds & tests

Balanced, labelled manifolds
Pressure test before the pour
Pressure held during the pour

04 · Screed

Plasticiser and cover ≥ 3 cm
Expansion joints set out
Full curing before start-up

05 · Start-up

Gradual first heat-up (in steps)
Commissioning record
Floor laid on a cured screed

Recurring defects

Diagnostics · site
Termo-igrometrica
Summer cooling condensation
CauseSurface below the dew point without dehumidification.
PreventionHumidity control, floor temperature kept above the dew point.
Meccanica
Screed cracking
CauseShrinkage, missing joints, no perimeter band, faulty first start-up.
PreventionExpansion joints, perimeter band, additive, correct screed heat-up.
Adesione
Pipe puncture / leak
CauseNails or screws during works, faulty fittings.
PreventionSurvey of the layout, pressure test before and after the pour.
Biologica
Mould from hidden leaks
CauseMicro-leaks in the screed, persistent moisture.
PreventionTightness test, pressure monitoring, accessible fittings.

Component materials

The network · materials
Marble
Expanded Synthetic Polymers
EPS — Expanded Polystyrene
Conglomerate
Concrete

Installation processes

The network · processes
PRC.09Screed and Underfloor Heating

Reference regulations

2 norms
  • D.P.R. 380/2001Consolidated Building Act (Testo Unico Edilizia)NazionaleIn force
  • D.M. 16/02/2007Fire-resistance classification of construction products and elementsNazionaleIn force

Informational links to the regulatory framework. Always verify the current text on the official source.

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