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Abstract
A series of laboratory tests using a large-scale environmental chamber has been carried out on two flat roof models fully insulated with cellulose fiber. These models represent typical flat roofs of urban houses, built in Montreal between 1930 and 1970. The insulating strategy consists of packing cellulose fiber to a density of approximately 4lb/ft3 in a single cavity roof between the roof planking and the ceiling plaster. The goal of the test program was to determine the performance of the assembly in terms of the risk of moisture accumulation in the roof assembly. The physical setup is a full-scale mock-up of the most common shallow flat roofs found in the Montreal area. The selection of the physical characteristics of the two test huts was based on thec haracteristics of 500 residential buildings. The two roof assemblies had different thicknesses, with one having 8 inches of insulation and the other 14. Each hut contained five roof cavities - one reference cavity without insulation and four insulated. One of the insulsated cavities was sealed with polyurethane foam at all of its bypasses and was hence subjected to little or no air leakage, while the other three cavities were exposed to both diffusion and air exfiltration conditions. The testing protoccol was developed to reprodcue wetting coditions slightly higher than typically found in these houses. The humidity transfer was monitored using three mthods: moisture content sensors in wood, relative humidity sensors in the insulation, and gravimetry for wood and cellulose speciments. The construction and the data collected are described int his paper. The difficulties in monitoring moisture transfer over long periods of time are also discussed. Major results ofthe 6-1/2 month test program using seven simulated climatic conditions are presented. Wetting and drying curves for roof cavities are also presented, and exposure time to moisture is compiled and presented. The reliability of the test procedure is discussed. This paper shows that the developed procedure permitted the assessment ofthe net moisture accumulation and the moisture exposure level after one complete wetting/drying cycle with precisely known conditions.
A series of laboratory tests using a large-scale environmental chamber has been carried out on two flat roof models fully insulated with cellulose fiber. These models represent typical flat roofs of urban houses, built in Montreal between 1930 and 1970. The insulating strategy consists of packing cellulose fiber to a density of approximately 4lb/ft3 in a single cavity roof between the roof planking and the ceiling plaster. The goal of the test program was to determine the performance of the assembly in terms of the risk of moisture accumulation in the roof assembly. The physical setup is a full-scale mock-up of the most common shallow flat roofs found in the Montreal area. The selection of the physical characteristics of the two test huts was based on thec haracteristics of 500 residential buildings. The two roof assemblies had different thicknesses, with one having 8 inches of insulation and the other 14. Each hut contained five roof cavities - one reference cavity without insulation and four insulated. One of the insulsated cavities was sealed with polyurethane foam at all of its bypasses and was hence subjected to little or no air leakage, while the other three cavities were exposed to both diffusion and air exfiltration conditions. The testing protoccol was developed to reprodcue wetting coditions slightly higher than typically found in these houses. The humidity transfer was monitored using three mthods: moisture content sensors in wood, relative humidity sensors in the insulation, and gravimetry for wood and cellulose speciments. The construction and the data collected are described int his paper. The difficulties in monitoring moisture transfer over long periods of time are also discussed. Major results ofthe 6-1/2 month test program using seven simulated climatic conditions are presented. Wetting and drying curves for roof cavities are also presented, and exposure time to moisture is compiled and presented. The reliability of the test procedure is discussed. This paper shows that the developed procedure permitted the assessment ofthe net moisture accumulation and the moisture exposure level after one complete wetting/drying cycle with precisely known conditions.
Date
12/1998
12/1998
Author(s)
P Fazio; D Derome; D Gerbasi
P Fazio; D Derome; D Gerbasi
Page(s)
3-14
3-14
Keyword(s)
flat roof; cellulose fiber insulation
flat roof; cellulose fiber insulation