Part I, Sealant Joint Calculation. For the wall panel shown above:

• Draw a sealant joint detail section cut through a horizontal joint (drawn to scale: full size) showing 4"-thick brick veneer, sealant, backup rod, and bond breaker; and indicating the dimensions - depth and width (use 1/8" increments) - of the sealant joint.

• Calculate sealant joint width:
  • length between horizontal sealant joints (panel dimension) = 12'
  • air temperature range is from -0 to +90 degrees F.
  • movement capability of 50%
  • cladding material expands over time by 2/100 of 1% (i.e., 0.0002 x original length) due to moisture absorption
  • maximum structural movement (story drift) is 1/8"
  • expect deviations in the panel alignment (construction tolerance) of 3/16"
  • neglect the impact of the glass opening; assume the entire exterior surface is brick for the purpose of this sealant joint calculation
  • For preliminary sizing, use: W = (100/X)[eL(DT) + M] + t; where:
    • W = required width of sealant joint;
    • X = % movement capability of sealant, i.e., 50;
    • e = coefficient of expansion of building "skin" material to be sealed = 0.0000036 (see below for examples);
    • DT = annual range between extreme temperatures (assume 130 degrees F if not known; in this case, use 90 degrees F);
    • L = length of cladding panels between vertical joints (i.e., joint spacing) = 12'
    • M = total anticipated nonthermal movement due to structural deflection, creep, moisture movement, etc.;
    • t = construction tolerance.

    Note: it is important that units are consistent. Convert all dimensions to inch units.

Coefficients of Expansion of Common Building Materials (in/in/degree F)

• Normal weight concrete 0.0000055

• Gypsum board 0.000009
• Gypsum plaster, sand 0.000007
• Glass 0.000005
• Acrylic glazing 0.000041
• Polycarbonate glazing 0.000044
• Polyethylene 0.000085
• PVC (vinyl) 0.000040

Find the total energy loss (BTU/hr) for just the wall panel shown above (including glass), assuming an outdoor temperature of 0 degrees F, and an indoor temperature of 70 degrees F. You can either find the average U-value for the wall and window, or compute separately the heat loss (BTU/hr) for wall and window and add together.

Also note that the heat flow, or total energy loss, expressed in BTU/hr, is given by the expression:

Q = U x A x (temperature differential); where U is the heat loss for each square foot of surface area with 1-degree F temperature differential, A is the total area of the panel (including both the wall and window area), and the temperature differential is 70 degrees F.

Window type

• double glazed with R=2.04; each panel contains two 6' x 4' windows.