Page 40 - JCAU-7-2

Journal of Chinese
Architecture and Urbanism Moisture damage in plastered heritage building

The comparative analysis of the BCW and HGS
buildings is presented in Tables 4 and 5.
3.1.2. Deterioration mechanisms of finish shedding

The river-facing façade of the BCW building exhibits surface
shedding of stone masonry blocks, caused by a combination
of physical and chemical factors. Comparative analysis reveals
that as the distance from the ground increases, the moisture
content of the walls also increases, correlating with intensified
masonry surface shedding. The porous and granular structure
of the stone masonry block makes it highly absorbent. In
humid environments, this moisture absorption compromises
the adhesion between internal particles and the surface,
leading to gradual loosening and eventual dislodging of
surface materials under repeated evaporation cycles (Geng et
al., 2023). Similarly, the river-facing façade of the HGS building
Figure 10. Footing deterioration and temperature change. Source:
Drawing by Jie Wei displays extensive plaster layer peeling and brick exposure. The
subtropical monsoon climate of Anchang historical town—
humid gases, which facilitate the migration of soluble salts characterized by high humidity, heavy precipitation, and
within building materials. As water evaporates, these salts insufficient eave protection—exacerbates the deterioration of
accumulate on the wall surface, forming whitish deposits. the plaster. Due to their interconnected pores, plasters exhibit
In severe cases, this can lead to corrosion, spalling, and high water absorption, which gradually reduces adhesion,
structural degradation of the masonry surface. leading to hollowing, cracking, and eventual detachment.
The most prevalent form of degradation in heritage 3.1.3. Mechanisms of deterioration development in
buildings is salt crystallization, often caused by wall moss encroachment
dampness and water infiltration. In Shaoxing, heavy and In high-humidity environments, the erosive effects
frequent rainfall contributes to high moisture content of moss growth on building materials are significantly
in the walls of buildings, resulting in visible watermarks
and darkened wall surfaces. As the moisture evaporates, enhanced, especially in areas with evident watermarks.
internal salts precipitate and form efflorescence (Cozzolino For example, the mortar plaster layer on the wall of the
et al., 2022; Gunasdi et al., 2023). HGS building, with its high porosity and water absorption,
creates ideal conditions for moss growth (Austigard &
In limestone-based finishing materials, prolonged Mattsson, 2019; Murgul & Kamskov; 2017; Trovão et al.,
water vapor infiltration causes internal moisture to 2020). As moss grows, its pseudo-roots invade the mortar’s
vaporize and expand, leading to hollowing, characterized interior, enlarging pore spaces and forming cracks, further
by bulging, cracks, and surface flaking. Cracking typically accelerating moss growth (Liu et al., 2020). Similarly, the
manifests as fine lines or crocodile skin-like patterns, stone masonry on the river-facing façade of the BCW
which can eventually lead to wall breakage and exposure building, which shows localized breakage and detachment,
of the structural layer. Dehiscence, observed near provides a favorable environment for moss growth.
structural elements, manifests as vertical cracks that could In addition to physical damage, chemical interactions
compromise the building’s structural integrity. between moss and the lime content of the walls contribute
Notable differences in wall finishing materials influence to deterioration. Organic acids secreted by mosses react
deterioration patterns. For instance: with the calcium carbonate in lime through acid-base
• BCW building: The walls are covered with cement neutralization, leading to corrosion, dissolution, and salt
mortar over brick, with a lime-faced base. Observed precipitation. These effects are especially pronounced at
degradation includes salt crystallization, spalling, the base of walls and other lower structural components
and biological colonization, such as moss and mold (Aloshan et al., 2024; Łowińska-Kluge et al., 2016).
growth (Zhao & De Angelis, 2020).
• HGS building: The walls are finished with plaster, and 3.2. Deterioration mechanisms of sunlight’s effects
the base is made of striped stone masonry. This building on building materials
exhibits additional forms of deterioration, including Sunlight is the most significant climatic factor affecting
powdering, hollowing, cracking, and dehiscence. buildings, indirectly influencing other environmental

Volume 7 Issue 2 (2025) 10 https://doi.org/10.36922/jcau.4606