Does FMV after lost = FMV before lost minus the cost of repair/replacement?

[man70]

I had to replace my roof in 2017 due to storm damage .

[rjs]

IRS Publication 547 says the following (pages 5-6).

You can use the cost of cleaning up or of making repairs after a casualty as a measure of the decrease in FMV if you meet all the following conditions.

• The repairs are actually made.
• The repairs are necessary to bring the property back to its condition before the casualty.
• The amount spent for repairs isn't excessive.
• The repairs take care of the damage only.
• The value of the property after the repairs isn't, due to the repairs, more than the value of the property before the casualty.