Because the windows are expected to last for an extended period of time and add to the value of the property, you should record them as an improvement and not an expense.
Per the IRS:
"Treasury Regulation § 1.162-4 provides that the cost of incidental repairs which
neither materially add to the value of the property nor appreciably
prolong its life, but keep it in an ordinarily efficient operating
condition, may be deducted. However, this regulation also provides that
repairs in the nature of replacements, to the extent that they arrest
deterioration and appreciably prolong the useful life of the property,
shall either be capitalized and depreciated in accordance with § 167 or
charged against the depreciation reserve."
Read more in the article below:
https://ttlc.intuit.com/replies/4209855
