Field Study on Hydrophobised Internally Insulated Masonry Walls

This paper presents a field study on the hygrothermal performance of hydrophobised masonry walls, provided with vapour tight or capillary active interior insulation. As a reference, also nonhydrophobised and non-insulated walls are analysed. To study the hygric performance, apart from traditional relative humidity sensors, in-house made moisture pins are embedded in the walls and are shown to yield valuable information in the high moisture range. Attention is given to the hygric performance of the wooden beam heads, the impact of wind-driven rain on the moisture conditions in the masonry wall, as well as to the impregnation depth of the water repellent agent. For the latter, the field study is supplemented with X-ray and liquid droplet measurements on a small semi-duplicate test wall. During the hydrophobisation process, an increased moisture level was induced. A drying period was needed to again reduce this level. After this period, a hydrophobic treatment showed a positive impact on the wall‘s hygric performance. The non-hydrophobised wall with a vapour tight interior insulation system showed the highest moisture level, especially deeper in the wall and thus where the wooden beam ends are located

Hygrothermal Analysis of Interior Insulation for Renovation Projects (Hygrothermische analyse van binnenisolatie bij renovatieprojecten)

The general objective of this thesisis a further elaboration of the current knowledge related to the hygrothermalperformance of interior insulation systems applied to single leaf masonry walls.To that aim, this study is based on numerical as well as experimental research,and specific attention is paid to both standard insulation systems and moreinnovative (capillary active) insulation systems. The impact of steady-statewinter conditions on the hygrothermal performance of these different interiorinsulation systems is studied based on a hot box-cold box experiment. Next, thestudy is extended to varying climatic conditions, including wind-driven rain, forwhich numerical simulations are used. Both approaches analyse the potentialmoisture accumulation in the capillary active insulation system, whichdecreases the thermal performance. Additionally, the potential influence thismight have on the indoor environment is examined. To ensure the reliableapplicability of capillary active interior insulation systems, case-specificstudies are recommended. As a second step, this study examineshow the hygrothermal performance of a thermal bridge is affected by interiorinsulation. To this purpose, the experiments first focus on the local surfacetemperature and the local heat transfer coefficient. To determine the localheat transfer coefficient, a methodology based on a combination of experimentaland numerical work is proposed. The results show that in cases of a junctionbetween an exterior and an interior wall, applying insulation at the interiorwall has a clear positive impact. Finally, the analysispays special attention to mould risk. It is shown that the different mouldgrowth models currently used in building simulation programmes tend to yieldwidely varying results. Therefore, this study offers an impulse to develop afurther evaluation of these mould growth models and offers some remarksconcerning experimental mould growth research. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}status: publishe

Wooden beam ends in combination with interior insulation: An experimental study on the impact of convective moisture transport

© 2018 Elsevier Ltd The risk free applicability of interior insulation in the presence of wooden beam ends is still a point of discussion. Two phenomena enlarge the risk on wood decay when interior insulation is applied: (1) a higher moisture load in the masonry due to a reduced drying potential and (2) a lower temperature in the masonry resulting in a higher risk on condensation if exfiltration of moist indoor air occurs. This paper studies - based on a hot box-cold box experiment - the impact of convective moisture transport and this for two vapour tight and one capillary active vapour open interior insulation system applied to a masonry wall with an embedded wooden beam. A comparison is made to a non-insulated wall. No wind-driven rain is included, making a pure analysis of convective moisture transport possible. For non-sealed beam junctions, a significant increase in relative humidity due to moist indoor air reaching the colder beam surface was clearly visible. The impact of air exfiltration was most pronounced for the capillary active system and was influenced by the way of sealing the airgap between the beam end and the wall. It is recommended to avoid air exfiltration as well as air circulation near the beam end. For mineral wool, the importance of an airtight sealing was less pronounced. An overpressure was found to influence the hygrothermal conditions near the beam ends of the poorly sealed test setups. Additionally, the convective air flow near the beam ends was analysed based on the measured temperatures.status: publishe

A comparison of the hygric performance of interior insulation systems: a hot box-cold box experiment

To increase the thermal performance of massive masonry walls, exterior or interior insulation can be used. The latter insulation technique is the most risky, though forms for example in cases of historical buildings, buildings with a worth-preserving facade or buildings in the urban context the only solution to increase the thermal performance of the wall. The current article compares the hygric performance of massive masonry walls provided with different interior insulation systems. To do so, small test walls are placed all together in a single hot box-cold box. The total moisture increase in the walls is measured by weighing the test walls. In addition, to investigate the working principle of the insulation systems the moisture distribution across the wall assemblies is investigated using the X-ray projection method. In the analysis capillary active as well as more standard non-capillary active insulation systems are investigated. For the imposed quasi steady-state winter condition, the increase of stored moisture inside walls with a capillary active system is found to be higher than for walls with a traditional vapour tight system. © 2014 Elsevier B.V.publisher: Elsevier articletitle: A comparison of the hygric performance of interior insulation systems: A hot box–cold box experiment journaltitle: Energy and Buildings articlelink: http://dx.doi.org/10.1016/j.enbuild.2014.04.033 content_type: article copyright: Copyright © 2014 Elsevier B.V. All rights reserved.status: publishe

Binnenisolatie van muren in historische gebouwen: systemen, risico’s en aandachtspunten

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Hygric performance of a massive masonry wall: How do the mortar joints influence the moisture flux?

Although masonry walls are a composite of mortar and brick, in numerical simulations the actual composition is often simplified to a homogenous brick layer. This article studies the impact of the mortar joints and the interface resistance for a massive masonry wall exposed to climate conditions. Also, a comparison to the moisture behaviour during an imbibition experiment is made. Whereas during an imbibition experiment the joints and brick–mortar interface resistances influence the moisture transport significantly, for real climate conditions a negligible impact is found. Consequently, for the investigated case a simplification to a homogenous brick layer is allowed.status: publishe

Capillary active interior insulation: Do the advantages really offset potential disadvantages?

© 2014, RILEM. Nowadays, capillary active interior insulation systems are often promoted because of their ability to avoid interstitial condensation, while a drying out remains possible. Additionally, their alleged performance to regulate the indoor climate is often used as a selling point. This paper compares the hygrothermal performance of a capillary active interior insulation system to this of a traditional vapour tight system. Where the previous studies on capillary active insulation systems mainly focused on historical buildings, this study investigates the applicability to standard single leaf masonry walls. Apart from the risk on interstitial condensation, also the impact on the indoor climate and the impact that wind-driven rain has on the hygrothermal behaviour of the retrofitted wall have been analysed. The capillary active system is found to be more sensitive to small modifications of the wall structure (e.g. interior finishing coat, wall thickness), while hardly any differences could be observed for the wall with a vapour tight system. In addition, wind-driven rain can hamper a good hygrothermal behaviour of a capillary active interior insulation system by inducing a lower thermal resistance or an increased indoor relative humidity. Therefore, it should be checked if the advantages of using capillary systems offset the potential disadvantages. A case-specific study is recommended to ensure the applicability of a capillary active interior insulation system.status: publishe

Wooden beam ends in combination with interior insulation: the importance of an airtight sealing

© 2017 The Authors. Published by Elsevier Ltd. The applicability of interior insulation when wooden beam ends are embedded in the wall is still a topic of debate, as interior insulation may imply an enlarged risk on wood decay. This paper shows the impact of convective moisture transport on the hygrothermal performance of the wooden beams. In a hot box-cold box experiment, a vapour open capillary active and two vapour tight interior insulation systems are studied together with a non-insulated reference wall. For each insulation system two configurations are analysed: one with and one without an airtight sealing between beam and insulation. The relative humidity at the beams without a sealing shows to be higher than found for those with an airtight sealing. This is especially true for the wall insulated with the capillary active system. Additionally, an overpressure is shown to influence the convective moisture transport and air flow around the wooden beams.status: publishe