Capital Expenditures (CapEx): Budgeting for the Repairs Your Cash Flow Doesn't See Coming
A rental that cash flows $300 a month looks healthy on paper. Then the roof fails in year six, the HVAC system dies in year nine, and the water heater goes in year twelve — and suddenly three years of "profit" disappear into a single invoice. The property wasn't actually profitable the whole time. It was profitable until the bill came due.
That's the problem CapEx budgeting solves: it forces the cost of big-ticket replacements into your monthly numbers, instead of letting them ambush you as one-time emergencies.
Why It Matters
Monthly cash flow only counts what you spent this month. It doesn't count the $9,000 roof you'll owe in year eight or the $5,000 HVAC system you'll owe in year twelve. If you don't set aside money for those in advance, your monthly cash flow number is overstating how profitable the property actually is — and you'll find out the hard way, at the worst possible time, with a contractor waiting for a deposit.
CapEx reserving turns a five-figure surprise into a predictable monthly line item. It's the difference between "we have to sell because the roof failed" and "the roof failed, and we've been saving for it for six years."
CapEx vs. Repairs: Know the Difference
Not every expense belongs in a CapEx reserve. The distinction matters because it changes how you budget and how you track the money.
Repairs and maintenance are routine, recurring, and typically under $500-$1,000: a leaking faucet, a clogged drain, a broken garbage disposal, lawn care, gutter cleaning. These come out of your operating expense budget and hit your cash flow the month they happen.
Capital expenditures replace or materially extend the life of a major system or structural component: roof, HVAC, water heater, major plumbing or electrical, windows, flooring throughout a unit, a new deck or driveway. These are infrequent, expensive, and predictable in the sense that every one of these systems has a known useful life — you just don't know the exact month it will fail.
The rule of thumb: if it extends the life of the asset rather than just keeping it running, it's CapEx.
How to Estimate a CapEx Reserve
The most common approach is a per-square-foot or percentage-of-rent reserve, refined by the age and condition of the property's major systems.
Percentage-of-rent method. Reserve 5-10% of gross monthly rent for CapEx, separate from your regular maintenance reserve (typically another 5-10%). A property renting for $1,800/month would set aside $90-$180/month purely for future big-ticket replacements.
Component method (more precise). Estimate the remaining useful life and replacement cost of each major system, then divide:
- Roof: 20-25 year life, $6,000-$12,000 to replace
- HVAC: 12-15 year life, $4,000-$8,000 to replace
- Water heater: 8-12 year life, $1,200-$2,000 to replace
- Flooring: 8-15 year life depending on material, $2,000-$6,000 per unit
- Exterior paint/siding: 7-10 year life, $3,000-$8,000
If a roof has 10 years of remaining life and costs $10,000 to replace, that's $1,000/year, or about $83/month, just for the roof. Add up every major system the same way and you get a property-specific CapEx number that's far more accurate than a flat percentage — especially useful when you're comparing a property with a 2-year-old roof against one where the roof is original to a 1998 build.
Where CapEx Reserves Go Wrong
Treating "positive cash flow" as proof a deal is good. A property cash flowing $200/month with no CapEx reserve isn't actually cash flowing $200/month — it's borrowing against a future repair bill it hasn't paid yet.
Reserving the same amount regardless of property age. A fully renovated property with a new roof, new HVAC, and new water heater needs a much smaller near-term CapEx reserve than a 1970s property with original systems, even at the same rent level. Age and condition should drive the number, not just square footage.
Never revisiting the number. Once you've replaced the roof, that portion of the reserve should shrink — you just bought yourself 20 years. CapEx budgeting isn't a set-it-and-forget-it percentage; it should be updated as major systems get replaced or as they age closer to end of life.
Spending the reserve on something else. A CapEx reserve only works as insurance if it's actually saved, not absorbed into general operating cash the first time a slow month happens.
How ProfitTrackr Helps
When you set up an owned property in ProfitTrackr, you can log recurring expenses at whatever cadence fits — including a monthly CapEx reserve line item, separate from routine maintenance. That means your monthly cash flow number already reflects the real cost of eventually replacing the roof or HVAC system, instead of showing an inflated figure that collapses the month a major system fails.
It also means when the replacement actually happens, you're not guessing whether you can afford it — your activity feed and expense history show exactly how much you've set aside and how it compares to the estimated replacement cost, so you can decide whether to pull from reserves, finance the repair, or delay a discretionary expense elsewhere in the portfolio.
Key Takeaways
- CapEx covers major system replacements (roof, HVAC, water heater, flooring); routine repairs and maintenance are a separate budget category
- A reasonable starting reserve is 5-10% of gross rent, refined using each system's age and remaining useful life
- Cash flow numbers that don't include a CapEx reserve overstate how profitable a property really is
- Update your reserve estimate whenever a major system is replaced or ages closer to end of life
- Budgeting CapEx monthly turns a five-figure emergency into a line item you already planned for
Related articles: Holding Costs: The Expense Investors Forget | Rehab Budgeting: How to Scope a Renovation