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9 Cards in this Set
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Thermal bridges |
high-conductivity structural elements which project partly or wholly through materials of lower conductivity. |
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What are some consequences of thermal bridging? |
Structural damage - which might be the result of thermal stressing due to differing temperatures gradients. Increased Exterior wall wetting - due to melting of wind-driven snow. Higher heat losses Dust marking Comfort problems |
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What can be done to prevent thermal bridging? |
Insulation can be placed over the entire exterior of a building..... Reduced number of ties and their sizes Provide thermal breaks when larger connection members are being used. .... article is actually not that helpful. |
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What is the pitfall of a one-dimensional heat flow calculation? |
it assumes that there is no interchange of heat between the member and the adjacent wall. This creates an error in the calculated temperatures because the lateral heat flow is not accounted for. Judgement in applying calculated values can be improved by comparison with measured values where available |
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True or False: One means of improving surface temperatures over a thermal bridge is to induce lateral heat flow on the warm side of the wall into the region of the bridge. |
True, |
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True or False: Failure to break thermal bridges in a steel stud wall assembly can result in a 50-80% reduction in the R-value of the insulating components. |
True, Wood framed walls are not as badly affected, but reductions of 10 to 20% are common |
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How can thermal bridging be effected by "off-sets"? |
With a masonry wall or exterior cladding requiring shelf angles the steel angle can be projected off the face of the frame with “off-sets." Steel “C-sections,” tubes or knife-edges attached intermittently to the structural frame to hold the steel angle away from the frame, allowing exterior insulation to run past the steel angle between it and the frame |
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What is the most common and most troublesome thermal bridge? |
Balconies |
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What can be done to treat the thermal bridging occurring at common balconies? |
It can be supported intermittently to break the thermal bridge and the gap between can allow exterior insulation to insulate the exterior wall.
Hang the balcony precast units with threaded rods tied back to the columns of the structural frame |
