Water infiltration: Are the windows always guilty?

Water infiltration near windows often leads to the premature conclusion that the windows in question are not performing well and are the cause of this water infiltration. This finding occurs mainly when infiltration is identified in the first years after installing a new window. In fact, if there is water infiltration, it is "normal" that they occur near windows, which are opening points in the building envelope which also prove to be points more vulnerable. 

Altogether, the building envelope is made up of several different materials and elements that are specifically put in place to seal the envelope and protect the walls framework and interior finishes. The different types of materials used for the building envelope and for the manufacture of windows have evolved a lot in recent decades, but the principle for the installation of these materials and windows remains essentially the same: all elements must have continuity and must direct water to the exterior part of the walls. However, the codes and standards for the manufacturing and installation of materials and elements of the building envelope have evolved with the advancement of materials and construction techniques available on the market. The windows are therefore one integral part of the various elements constituting the building envelope. However, the failure or deficiency of any of these elements can result in water infiltration and not just the windows themselves. The rain, combined with the wind, also has a direct impact on the performance of all elements of the building envelope, including the windows. 

Hence, following the discovery of water infiltration near a window, the inspection by an expert, in particular using exploratory openings in the deteriorated areas and the use of a standard watering test, allows to objectively determine the probable cause of the water infiltration, the potential involvement of the window, as well as the possible connection with a deficient installation or lack of continuity of various elements of the building envelope.

Therefore, before concluding that the performance of a window is the cause of water infiltration, a good understanding of all the elements ensuring the waterproofing of the building envelope is essential. Let's do justice to the windows!

by Fabio R. Melo, P. Eng., M.SC. - Civil Engineering Department