The objective of this thesis was to study airthightness of houses built in Finland in the 1940’s and 1950’s and also try find out the most common air-leakage places in them. This thesis was made as part of IEEB –project to Oulu University of Applied Sciences.

In this thesis 9 single family houses located in Oulu, Finland was measured by pressure test to find out their air-tightness. Pressure tests were made by standard SFS-EN 13829 with method B. Measurements were made with Minneapolis Blower Door air-tightness measuring equipment. In connection with air-tightness tests thermal imaging were made with FLIR B400 Western –thermal camera. By using the computer program made by the makers of the air-tightness measuring equipment we got air-tightness reports. From the thermal images we took we made detached thermal imaging reports with FLIR Reporter computer program. All gathered information was reported to the database made to the IEEB –project.

From air-tightness tests we received n50 and q50 numbers. From all the measured houses n50 number was in between 4,6 to 11,8 (1/h) and q50 number was in between 4,1 to 11,2 [m3/(m2*h)]. Average of n50 number was 7,2 (1/h) and q50 number 7,0 [m3/(m2*h)]. Comparing measure results set by the Finnish constructing instruction collection part D3, all of the buildings were in G-class which is the worst class. Leakage places located by thermal imaging were made as chart in which percentage of the leakages were shown. From all the leakage places most of them were located in the connection of ceiling and outer wall with the percentage of 31 from all located air-leakages. Air-tightness- and thermal imaging reports were set to the owners of the houses. Using them it is easier to the owners to make the necessary repairments.