The Measured Summer Performance Of Tile Roof Systems And Attic Ventilation Strategies In Hot, Humid Climates

Secondary Author(s)

Chandra, Subrato

Report Number





Residential; Buildings; Roofs; Cooling


During 1994, simultaneous full-scale testing of residential plywood-decked roofing system was conducted using a flexible roof facility (FRF). The facility consists of a 24-ft by 48ft rectangular building with one large conditioned space under an attic that is partitioned into six separate test cells. Throughout the test protocol one cell was configured as a residential black-shingle roof system, employed as the baseline for comparison of the alternative roofing systems.Two identical cells were employed during the summer of 1994 to investigate soffit and ridge venting. Tests of two different configurations best illustrate the results. A comparison of a sealed attic to an attic with high-profile ridge-vent and well-vented soffits (1 ft2 of soffit/50 ft2 of attic floor) showed that the vented attic reduced the ceiling heat flux by 66%. Also, a comparison of the well-vented attic (1 ft2 of soffit/50 ft2 of attic floor) to an attic with a perforated soffit (1 ft2 of soffit/230 ft2 of attic floor) showed 25% less ceiling heat flux through the well-vented attic. The effects of ridge venting (on this roof with a simple geometry) seem to be nominal when compared to the effect of soffit venting, causing, at best, a 4% heat flux difference. A simultaneous study was carried out to determine the thermal effects of tile roofing systems. Also investigated was the effect of venting on tile roofs. A tile roof was installed on cell 1 on August 27, 1993. This roof was built to maximize under-tile ventilation and ridge ventilation. It featured a counter-batten installation modified to provide venting under the tile and out of the attic cavity. On September 1, 1994, a direct-nailed tile roof was installed on cell 4. The vented tile roof reduced ceiling flux by 48% compared to the black-shingle roof, whit the direct-nail installment returned a flux reduction of 39%. It appears that the tile thermal mass and interstitial ventilation around each tile are the predominant phenomena reducing the cooling load in such roofs.

Date Published



Buildings - Cooling; Buildings - Residential; Buildings - Roofs

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