Latest generation ventilated roof

tetto ventilato

The Tegola Canadese “ventilated roof” strives for perfection, becoming at the same time simpler and also better performing.

The IWIS Group, manufacturer of TEGOTHERM insulating boards, has created a new type of insulating board, featuring the “TV” acronym, conceived for the installation of the Tegola Canadese ventilated roof: the AVF TV and XPS TV boards create a first necessary housing for the first row of battens, which lean directly on the insulating material.

The boards are available in two 100 mm thick versions:
XPS TV in extruded polystyrene with λD=0.036 W/mk
– AVF TV in polyiso (PIR) and gas-proof A-Cell® facer with λD=0.023 W/mk

Characteristics of the AVF TV and XPS TV ventilated roof system

  • Special rebating specifically conceived for the first set of battens (50 x 60 mm rafters);
  • Reduction of the thermal bridging at the board joints, as the rafters lean on 40 mm of insulating material;
  • Further rebating for the interlocking of the insulating boards, therefore reducing the overall thermal bridging;
  • Reduction of the number of battens per m² for the first frame: with traditional methods, the use of battens is equal to 3.12 ml/m² (two battens every 64 cm), while the new technology only requires 0.83 ml/m² (one batten every 120 cm);
  • Use of only one batten size for the whole ventilated roof: 50x60 mm;
  • Reduction of fastening positions (-50%);
  • Reduction of the number of insulating boards installed (-50%)

Ventilated roof layers using XPS TV

XPS TV
Sizes 1200 x 600 mm
Thickness 100 – 140 mm
ɅD= 0,036 W/mK – 0,038 W/mK
Smooth skin

Ventilated roof layers using AVF TV

AVF TV
Sizes 1200 x 1200 mm
Thickness 100 mm
ɅD= 0,023 W/mK
Gas-proof A-Cell® facer

Advantages

QUICK AND EASY INSTALLATION

QUICK AND EASY INSTALLATION

as all the insulating boards are installed on the roof first, followed by the first and second set of battens;

HIGH THERMAL INSULATION PERFORMANCE

HIGH THERMAL INSULATION PERFORMANCE

thanks to the reduction of the overall thermal bridging, and the use of high performance insulating materials, which keep their insulating characteristics unchanged in the long term;

LIGHTNESS

LIGHTNESS

of the package, as the special rebating housing the battens allows for a lower use of structural elements and fastenings, therefore reducing the overall roof weight;

ECONOMY

ECONOMY

of the whole roof package, as thanks to the lower number of battens and fastenings, and most of all the quicker and easier installation procedure, this system provides significant labour cost savings;

STABILITY AND COMPACTNESS

STABILITY AND COMPACTNESS

of the roof, thanks to the housing of the first set of battens within the insulating layer, and subsequent reduction of the length of the fastenings.

Thermal performance and construction technology

The ventilated roof built using AVF TV and XPS TV boards meets the thermal transmittance limits set by Italian Legislative Decree 311/06 and subsequent amendments and integrations, for all the Italian climate zones and for the months of maximum summer sun. In Italian locations with irradiance exceeding 290 W/m², and in general in roof with a surface mass below 200 kg/m², the AVF TV board reaches and meets the thermal performance set by Art.2 of Italian Presidential Decree 59/09, meaning a periodical thermal transmittance YIE lower than 0.20 W/m²K

SECTION OF THE LATEST GENERATION VENTILATED ROOF

Roof ventilation

The worldwide attention for the protection of the environment has made energy savings in buildings a main factor, resulting in the promotion of environmentally friendly solutions. This has in turn brought to the development of technologies aimed at keeping constant temperatures inside buildings, with limited energy usage. The “ventilated roof” technology, which together with insulation is the most important passive solution for temperature and humidity comfort inside buildings, is aimed at keeping constant indoor temperature with limited energy consumption, whilst also increasing the useful life of the roof structures, by protecting them from humidity and mould.

The ventilated roof can be considered such when the outer covering is detached from the insulating layer (or the installation structure/laying surface, should no insulation layer be present), creating a gap where an upward air flow develops. When heating, due to conduction/convection caused by the heating of the covering exposed to the sun, the air increases in volume and decreases in weight, travelling to the top of the roof and then escaping from the roof ridge, therefore causing the suction of fresh air from the gutter. This gradually removes the heat that develops on the roof covering, preventing it from travelling through the building. In winter, air circulation will always keep the insulation well ventilated, and therefore dry, avoiding the formation of inner condensation and preserving its insulating performance, in addition to the quality and functionality of the roof structures.

HOT SEASON

WARM ROOF

1. The roof top heated by the sun rays transmits the heat to the insulating material, which can work as thermal retardant: the heat then transfers to the roof supporting structures and to the inside of the building.

VENTILATED ROOF

The fresh air inside the ventilation chamber heats due to the sun rays, becomes lighter and escapes from the roof ridge, taking heat away from the insulating material.

COLD SEASON

WARM ROOF

Due to the low temperatures, condensation can form within the roof structure, causing mould, humidity and dew.

VENTILATED ROOF

In winter the air circulation will keep the insulating material dry, therefore preventing the formation of condensation and helping to preserve the roof construction elements in the long term

SNOW

WARM ROOF

In mountain regions, there can often be the formation of dangerous ice barriers at the eave, due to infiltrations in the roof structure.

VENTILATED ROOF

The ventilation promotes even melting of the snow on the roof, therefore avoiding the formation of ice barriers at the eave.

Comparison tests and the advantages of ventilation

Below are some tests and their results, which give an objective view of the advantages, based on the type of roof structure, which of course has a significant impact.

Presumed environmental conditions:

  • ambient air temperature +25°C;
  • roof covering temperature +80°C;
  • roof covering temperature +80°C;
  • lack of wind;
  • same insulating material of same thickness for all the tests.

CONCRETE
STRUCTURE

WARM ROOF

- Plaster temperature after about 10 hours of sun exposure: +34.5°C
- W/h absorbed: 523 per m2 of roof

VENTILATED ROOF

- Plaster temperature after about 10 hours of sun exposure: +27.5°C
- W/h absorbed: 116 per m2 of roof

WOODEN
STRUCTURE

WARM ROOF

- Wood panelling temperature after about 10 hours of sun exposure: +42.1°C
- W/h absorbed: 319 per m2 of roof

VENTILATED ROOF

- Wood panelling temperature after about 10 hours of sun exposure: +31.2°C
- W/h absorbed: 116 per m2 of roof

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