Hygrothermal assessment of internally insulated solid masonry walls fitted with exterior hydrophobization and deliberate thermal bridge

Abstract

Relative humidity (RH) and temperature were measured in several solid masonry walls with embedded wooden beams, fitted with autoclaved aerated concrete (AAC) thermal insulation on the interior surface and exposed to a cool, temperate climate. The field study was based on the use of a 40-feet insulated reefer container reconfigured with eight 1 × 2 m holes containing the solid masonry walls. The study investigated the influence of AAC thermal insulation on the interior side with a combination of exterior hydrophobization and a deliberate thermal bridge in front of the embedded wooden wall plate using a material with higher thermal conductivity.Validated HAM simulations were used to investigate the effect of controlling the indoor humidity, and how this would affect the theoretical risk predictions from the damage models. Experimental findings indicate that hydrophobization of solid masonry walls with internal insulation have both positive and negative effects on the moisture balance of the wall, in relation to moisture-induced damage, and that a deliberate thermal bridge installed in front of the embedded wooden wall plate can reduce the moisture content in the wooden elements. Simulation findings indicate that a combination of exterior hydrophobization and decreased indoor moisture load can reduce the RH to acceptable levels in relation to moisture induced damage at the interface between existing wall and new insulation. No major changes were observed in relation to the risk of frost damage at the exterior surface. K E Y W O R D Sdamage models, field study, hydrophobization, internal insulation, mineral insulation board

Hygrothermal assessment of four insulation systems for interior retrofitting of solid masonry walls through calibrated numerical simulations

“…This would mean less potential for diffusion in the outwards direction and in turn less interstitial condensation. Previous field studies [15], [37] and simulation studies [14], [15], [29], [31], [38]- [40] have shown improved hygrothermal performance in the critical locations in the case of reduced indoor moisture load. The case studies in [7], [21], [23], [24] showed acceptable performance in the interface between the existing wall and the insulation system while subjected to a low indoor moisture load (studies were primarily using diffusion-open systems).…”

Hygrothermal assessment of solid masonry walls internally insulated with bio-based insulation materials

“…Hourly data were used for the mathematical mould-growth modelling. Measurement data and VTT modelling results are available in the supplementary files [12]…”

Decisive Parameters for Moisture Safe Internal Insulation of Masonry - Long Time Monitoring in Inhabited Dwellings

“…This leads to reduced drying capability and perhaps increased moisture content in the wall when combined with covering the internal surface of the wall with a material. As a result, there is a possibility of moisture-related issues like frost damage at the exterior surface, rot in the wooden beam ends, high relative humidity, or even interstitial condensation at the interface of internal insulation and the original wall, where, as a result, mold may appear [2,[17][18][19].…”