The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.

Methods and Instrumentation for Measuring Moisture in Building Structures

Jukka Voutilainen

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S2 at Helsinki University of Technology (Espoo, Finland) on the 18th of March, 2005, at 12 o'clock noon.

Dissertation in PDF format (ISBN 951-22-7523-6)   [4435 KB]
Dissertation is also available in print (ISBN 951-22-7522-8)


Excess moisture in building structures may damage the structures and provide suitable conditions for microbe growth. As a consequence, moisture may cause different health effects to the occupants, and lead to costly refurbishments, if the damage is not perceived in time. Currently, there are several work-intensive, destructive methods for verifying suspected moisture problems and for monitoring the drying of concrete structures. However, it has not been previously feasible to monitor moisture routinely, on a regular basis.

This thesis introduces new methods for measuring moisture in building structures, and the instrumentation developed for implementing them. First of all, the study defines accurately the current need for new methods, and selects the specific problems to approach. The study then elucidates the physical principles of the novel measurement methods and presents the practical instrumentation. The functionality of the system is then verified in laboratory and field measurements. Finally, some guidelines are presented in how to apply the system to the building industry.

The developed measurement system consists of two components: low-cost passive LC circuit sensors and a separate reading device that couples inductively with each sensor. The sensors are assembled in contact with the structure of interest at the time of construction or renovation. The moisture conditions in the structure affect the resonant frequency and quality factor of the sensor. These parameters can be measured with the reading device from outside the structure, whenever needed. As a consequence, moisture conditions inside the structure can be measured without damaging the structure. As an improvement to existing moisture measurement methods, the developed system combines measurement accuracy at an exactly defined location with a fast and non-destructive measurement procedure. In addition to the methods, this thesis presents several, new moisture and temperature sensors, a hand-held device for reading the sensors wirelessly, and preliminary measurement results and experiences from using the system in the construction industry. The research lays a foundation for further research in the moisture measurement application, but also for applying the methods to other application areas, such as the packaging industry. The research has also led to the development of a new commercial product.

Keywords: moisture, humidity, measurement method, RFID, inductive coupling, embedded systems

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© 2005 Helsinki University of Technology

Last update 2011-05-26