PRlNClPLES/DEFECTS
Component Connections
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Floor /wall
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Window /wall
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Wall/roof
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Column/wall
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Wall/wall
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Wall/ceiling
The connections between building components are associated with many thermal defects including
air leakage, thermal bridging and insulation defects. Most occur because inadequate attention is
given to maintaining the continuity of the insulation layer and the air barrier system at these
connections. Particular concern has been directed towards the intersection of the floor slab and the
exterior wall (Chang, Childs, Fang), the installation of the window in the wall (Rousseau,
Patenaude), and the wall/roof junction (Riedel, Turenne). The floor-wall connection is often the site
of significant thermal bridging when the floor slab penetrates the wall insulation. This location is
also often the site of air leakage. Window-wall connections are associated with several thermal
defects including air leakage and air barrier discontinuities, insulation voids and compression
around window frames, positioning the thermal break of the window system such that air is able to
infiltrate around it, and designs in which the area of the window frame exposed to the outdoors is
larger than the area exposed to the indoors. This last defect causes the inner frame to be cold,
increasing the potential for condensation. The wall-roof junction is a common location for air
leakage due to discontinuities between the wall air barrier and the roof membrane. The wall air
barrier may or may not extend to the roof deck, and the roof membrane is seldom sealed to the wall
air barrier. Rather, the membrane is often turned up at the roof edge, leaving a discontinuity in the
envelope air barrier at this junction. Examples of thermal defects at wall/roof intersections are
presented in the section Systems/Roofing Systems.
The connections between walls and structural columns and between different wall systems can be
associated with thermal bridges and insulation defects. These connections are also associated with
air leakage due to the use of air sealing systems which can not accommodate differential
movements between the two different components. This situation was discussed earlier with
reference to concrete block masonry walls and structural columns and spandrel beams. Also
discussed earlier, the intersection of the wall and a suspended ceiling is sometimes associated with
inadequate airtightness and missing insulation when materials and finishes are not carried up
above the ceiling level to the floor above (Handegord, Kudder).
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