Influence of omitting the vapor barrier in light timber frame walls with bio-based insulation on the risk of mold growth and indoor climate: A literature review
article
This paper aligns with the rising interest in improving indoor comfort and health of
occupants by moisture buffering with hygroscopic materials and the use of bio-based
materials with low embodied emissions. The study focuses on literature on light timber
frame walls (LTFW) with bio-based insulation and hempcrete walls, both without a
vapor barrier. The aim is to highlight the consequences of omitting the vapor barriers
in such wall assemblies and to ensure their durability. This review examines two main
questions. Firstly, is there a risk of mold growth in LTFW with bio-based insulation and
no vapor barrier? Secondly, are there possible links between these building envelopes
and the indoor climate and its potential effects on occupants? The findings show that
the risk of mold growth in vapor-open walls depends on the external climate, user
behavior and applied materials. It is influenced by several factors such as vapor pressure
difference, water vapor resistance ratio, exterior finishing, presence of a ventilated
cavity, and the hygroscopic properties of insulation materials. Vapor-open walls exhibit
a higher risk of mold growth between insulation and exterior lining compared to walls
with vapor barriers. Additionally, there is a lack of field studies that visually examine mold growth in vapor-open buildings. While simulations suggest that vapor-open build ings with hygroscopic insulation can buffer interior relative humidity fluctuations, sup porting field studies are limited. Further research and field studies are needed to improve the understanding of vapor-open or permeable building and its implications on mold growth as well as on the indoor climate and effects on occupants.
occupants by moisture buffering with hygroscopic materials and the use of bio-based
materials with low embodied emissions. The study focuses on literature on light timber
frame walls (LTFW) with bio-based insulation and hempcrete walls, both without a
vapor barrier. The aim is to highlight the consequences of omitting the vapor barriers
in such wall assemblies and to ensure their durability. This review examines two main
questions. Firstly, is there a risk of mold growth in LTFW with bio-based insulation and
no vapor barrier? Secondly, are there possible links between these building envelopes
and the indoor climate and its potential effects on occupants? The findings show that
the risk of mold growth in vapor-open walls depends on the external climate, user
behavior and applied materials. It is influenced by several factors such as vapor pressure
difference, water vapor resistance ratio, exterior finishing, presence of a ventilated
cavity, and the hygroscopic properties of insulation materials. Vapor-open walls exhibit
a higher risk of mold growth between insulation and exterior lining compared to walls
with vapor barriers. Additionally, there is a lack of field studies that visually examine mold growth in vapor-open buildings. While simulations suggest that vapor-open build ings with hygroscopic insulation can buffer interior relative humidity fluctuations, sup porting field studies are limited. Further research and field studies are needed to improve the understanding of vapor-open or permeable building and its implications on mold growth as well as on the indoor climate and effects on occupants.
Topics
TNO Identifier
1028984
Source
Journal of Building Physics, pp. 1-37.
Pages
1-37