The distinction you're working with is between a deductible repair and a capital improvement. A repair keeps a property in the condition it's already in and comes off the current year's income. An improvement adds value or extends the life of the property, and it goes onto the balance sheet as an asset and gets depreciated over years instead. A full tear-off and replacement of an entire roof is the textbook example people use for the improvement side, because you've replaced a whole structural component rather than patched it.
There are safe harbors in the tax rules that let some spending be expensed even when it looks like an improvement, and the dollar thresholds and the eligibility conditions attached to them change and depend on the taxpayer's situation. Which one applies to your client is a call for his licensed tax preparer, not for you or for his old bookkeeper's habit.
What you did by parking it in fixed assets pending review is the right move mechanically, because the books can hold the item and the invoice detail while somebody qualified decides. Ask the roofer for a breakdown showing how much of the $9,400 was decking replacement versus shingles, since a split invoice gives the preparer something to work with instead of one lump.
One thing that catches new bookkeepers: the books and the tax return don't have to match on this. A CPA can capitalize something for tax that you carried differently for book purposes, and the depreciation schedule the CPA keeps is usually the authoritative one. Ask for a copy of it every year and tie your fixed asset list to it.
