Influence Of The Upper Ventilation Level Of Thermally Insulated Roofs On The Dry-out Behaviour Of ..


An attempt was made to determine the influence of the size of the upper ventilation space of a thermally insulated roof  on the dry-out behaviour of clay roofing tiles and, based on  the results, to draw conclusions regarding the frost resistance of a roof surface with different insulation systems.  A roof test rig was erected which made it possible  to determine the dry-out time under varying conditions, including internal and external air flow, roof pitch, and type, shape and surface finish of the tiles.  The ventilation cross-section was changed in three stages: full ventilation, reduced ventilation, and full insulation.  It was found that the size of the upper ventilation space has a  crucial effect on tile dry-out behaviour, and hence frost resistance.  For higher porosity tiles with untreated and engobed surfaces, the dry-out rate falls considerably in a full rafter insulation compared to ventilated cross-sections; the effect is greater for a steep roof pitch  and higher exterior temperature. Depending on air humidity, low-porosity tiles show contrary behaviour.  8 refs.

Primary author(s): Rossbach M

                            Institut fur Ziegelforschung Essen eV

Source: ZI-Annual. Annual for the Brick and Tile, Structural

            Bauverlag GmbH,Wiesbaden & Berlin,2002,p.78-87

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