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The study investigated the hygrothermal performance and risk of fungal growth in a phenolic foam system with a closed cell structure and a diffusion-open and capillary active lime-cork based insulating plaster, for internal retrofitting purposes. The setup comprised two 40-feet (12.2 m) insulated reefer container with controlled indoor climate, reconfigured with 24 holes (1 × 2 m each) containing solid masonry walls with embedded wooden elements on the interior side. Focus was on the conditions in the masonry/insulation interface and embedded wooden elements, and the performance of the two systems were compared to three diffusion-open insulation systems and one diffusion-tight. The effect of exterior hydrophobisation was also investigated. Relative humidity and temperature were measured in several locations in the test walls over 2½ years, and the risk of fungal growth was evaluated by on-site measurements and the VTT mould-growth model. The findings indicate that internally insulated walls with bare brick exterior surfaces performed poorly with high risk of fungal growth. The effect of exterior hydrophobisation was found to vary with the orientation and the installed insulation system, with a generally positive effect on walls facing south-west but limited effect for north-east. Furthermore, the more diffusion-tight insulation systems were found to perform better in combination with exterior hydrophobisation than the highly diffusion-open systems. The lime-cork insulating plaster showed high relative humidity and risk of moisture-induced problems. The on-site fungal tests showed no growth in the masonry/insulation interface inside the two insulation systems, probably due to high initial pH-value.

The objective of this study was to test whether compliance with the current Danish best practice recommendations concerning design of the cold attic space will prevent damaging moisture levels. The project was performed as a full-scale experimental setup in the cool temperate climate of Denmark. The setup comprised 18 north-facing attic spaces with varying ventilation principles and varying infiltration scenarios. The relative humidity and temperature were measured in attic spaces, indoor and outdoor, for almost 3 years. The hygrothermal performance of the attics was evaluated by post-processing and comparing the data with predicted mould growth risk and with visual observations of mould growth. The results showed that following the recommended passive ventilation strategies made the hygrothermal performance in attics with diffusion-open roofing underlay worse. In addition, increasing vapour diffusion tightness of the roofing underlay made the hygrothermal performance of the cold attic spaces under the eaves worse, except for attics with passive ventilation but without infiltration. The hygrothermal performance of the attics with diffusion-tight roofing underlay was poor when combining infiltration and the assessed ventilation strategy. The performance of the same attic without infiltration showed that some degree of ventilation was needed. External roof insulation did not significantly improve the hygrothermal performance of the attic.

This project investigated fungal growth conditions in artificially contaminated interfaces between solid masonry and adhesive mortar for internal insulation. The project comprised several laboratory experiments: test of three fungal decontamination methods; investigation of development of fungal growth in solid masonry walls fitted with five internal insulation systems; and investigation of volatile organic compounds (VOC) diffusion through materials and whole insulation systems. One aim was to examine whether the alkaline environment (pH > 9) in the adhesive mortars could prevent fungal growth despite the water activity (a w ) in the interface exceeds the level (a w > 0.75) commonly considered critical for fungal growth. The findings indicate that do-it-yourself decontamination solutions were inadequate for removal of fungal growth, while professional solutions were successful. However, the choice of decontamination method was of minor importance in the case of application of internal insulation with high pH adhesive mortar, as the high pH adhesive mortars were found to inactivate existing growth and prevented spore germination during the experimental period. The three tested VOCs were capable of diffusing through most of the examined products and could potentially affect the indoor air quality.

The study investigated the hygrothermal performance and risk of mould growth in two thermal insulation systems for internal retrofitting purposes; a phenolic foam system with a closed cell structure, and a capillary active diffusion-open lime-cork based insulating plaster. The setup consisted of a 40-feet (12.2 m) insulated reefer container with controlled indoor climate, reconfigured with several holes (1x2 m each) containing solid masonry walls with embedded wooden elements on the interior side and different interior insulation systems, with and without exterior hydrophobisation. Focus was on the conditions in the interface between wall and insulation system, and in the embedded wooden elements. Relative humidity and temperature were measured in several locations in the test walls over two years, and the mould risk was evaluated by measurements and the VTT mould growth model. Findings for the interior phenolic foam system indicated that exposed walls experienced high relative humidity and high risk of moisture-induced problems. Exterior hydrophobisation had a positive effect on the moisture balance for the southwest oriented wall with phenolic foam. The lime-cork based insulating plaster showed high relative humidity and risk of moisture-induced problems, with and without hydrophobisation.

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

In historic masonry buildings, wood can be embedded in the walls as storey partition beams, or as supportive wall plates. Half-timbered masonry constructions, or wooden frames, e.g. combined with internal insulation, are other examples of wooden elements. Wood decaying fungi can cause serious damage to wood, which may lose mass and strength, ultimately yielding the risk of collapse. In addition, some fungal species may even be hazardous for occupants. All wood decaying fungi depend on favorable moisture and temperature conditions, although the threshold conditions may vary with various fungal species and types, and state of the wood. To predict the risk of occurrence of wood rot, several models have been developed, however most of these are based on a limited number of experiments, or very specific cases. For these reasons, the applicability of the models to other scenarios (fungal species, wood species) may not be appropriate. Furthermore, another failure mode for wood and moisture, is mold growth, which is initiated at lower moisture levels. An indication of risk of mold growth would indicate problems or risks before the initiation of wood rot. Mold growth does not deteriorate the wood, but is usually equally undesired due to health concerns of occupants. For this reason, there might be places where some mold growth would be acceptable, e.g. embedded beam ends if there is no transfer of air from the moldy area to the indoor air. Therefore, risk of rot could be important. The paper investigates models for mass loss due to wood decay and mold growth based on exposure time to favorable hygrothermal conditions. The investigation is based on inspection of wood samples (wall plates) from a full-scale experimental setup of masonry with embedded wood and monitored conditions, to which the prediction models will be applied. Monitored hygrothermal conditions were implemented in mold and wood decay models, and samples were removed from the test setup. The implemented models yielded high mold index and mass loss, whereas neither mold nor decay was observed in the physical samples. Results indicate that the implemented models, in these cases appear to overestimate the risks of mold and rot in the supportive lath behind the insulation.