Transfer Grille Size Calculator
Adjust the data in the blue boxes, press enter or click "Calculate"
Needed Transfer Grille Area
Jump Duct Diameter
24.5 inches square (0.2 sq. ft.)
If the free area of grille is
, and side (a) is
" , side (b) should be
The calculated grille area will be large enough to maintain less than 0.012" wc (3 pascals) pressure difference to prevent the pressurization of bedrooms and depressurization of the common area. This limits the amount of air that will be forced into or drawn from the attic, crawlspace etc. More info on transfer grilles from this link;
The Building Science Corporation.
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