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1. Repaint every four years.
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P |
$5.12 |
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{t(P-S)/n}(P/A, i%, n) |
$1.87 |
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-(1-t)(X)(P/F, i%, n) |
-$2.11 |
n=4 |
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-(1-t)(X)(P/F, i%, n) |
-$1.55 |
n=8 |
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S(P/F, i%, n) |
0 |
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PW |
-$6.91 |
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A |
-$0.917 /m2 |
2. Biennial touch-ups instead of repaints every four years.
Biennial touch-up costs (X) at 2, 4, 6, 8, and 10 years can be expressed as an equivalent annual touch-up cost X’ with the following Equation:
X’ = X[(P/F, 8%, 2y) + (P/F, 8%, 4y) + (P/F, 8%, 6y) + (P/F, 8%, 8y) + (P/F, 8%, 10y)](A/P, 8%, 12 y)
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(P/F, i%, n) |
n |
0.857 |
2 |
0.735 |
4 |
0.630 |
6 |
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0.540 |
8 |
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0.463 |
10 |
and X' = 0.4281 X
Repainting costs alone can be expressed similarly with the following formula:
A = -P[(P/F, 8%, 4y)+ (P/F, 8%, 8y)](A/P, 8%, 12 y)
or -$0.866 /m2
To be equal or less costly the annual equivalent annual cost of touch-ups should be equal or less that the repaint program, and hence:
0.4281 X = -$0.866 and X = -$2.024
