SEDL / STP / STP959-EB / STP25721S

A Heat Transfer Analysis of Metal Fasteners in Low-Slope Roofs

Burch, DM
Mechanical engineer and cooperative education students, National Bureau of Standards, Gaithersburg, MD

Shoback, PJ
Mechanical engineer and cooperative education students, National Bureau of Standards, Gaithersburg, MD

Cavanaugh, K
Mechanical engineer and cooperative education students, National Bureau of Standards, Gaithersburg, MD

Pages: 11    Published: Jan 1987

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Abstract

The heat transfer through cylindrical metal fasteners with metal caps, in low-slope roofs having metal and wood decking, is analyzed using finite-difference theory. For a representative case of 5.4 fasteners/m² (4.5 fasteners/yd²), metal fasteners were found to reduce the overall thermal resistance of low-slope roofs with metal decking from 3 to 8% for insulation thicknesses ranging from 25 to 150 mm (1 to 6 in.). The effect of metal fasteners on the overall thermal resistance of low-slope roofs with wood decking was found to be about one-half their effect on roofs with metal decking. The use of plastic instead of metal caps on the metal fasteners reduced the thermal bridging of the individual metal fastener by 44%.