Quick answer
A CapEx reserve planner spreads the cost of big, infrequent repairs over their lifespan so you save monthly instead of being ambushed. A typical single-family rental needs about $246 a month per unit on the planner's default schedule: roof $12,000 over 25 years ($40 a month), HVAC $8,000 over 15 years ($44), plus water heater, appliances, paint, flooring, plumbing and driveway. Skip the reserve and the 'profitable' years are borrowing from the roof year.
How the CapEx Reserve Planner works, step by step
List each major component with its replacement cost and expected lifespan: roof, HVAC, water heater, appliances, exterior paint, flooring, plumbing and driveway. The planner divides each cost by its lifespan to get the annual reserve for that item, then totals them per property and multiplies by your unit count across the portfolio.
Use lifespans from a published source rather than guessing. The NAHB and Bank of America life-expectancy study puts an asphalt shingle roof at about 20 years, a furnace at 15 to 20, a heat pump at about 16, central air conditioning at 10 to 15 and a tank water heater at about 10 — though the study itself warns these are general guidelines, and climate and maintenance move them materially.
Adjust for age, not just lifespan. A roof with 5 years of life left does not need cost ÷ 25 — it needs cost ÷ 5 from you, unless the previous owner funded the reserve (they did not; you bought their unfunded liability, which is why purchase inspections price remaining life). Where the planner allows lifespan inputs, shorten them for mid-life components; otherwise treat an older building as needing a higher monthly figure than the straight average.
Hold the reserve in a separate account and do not count it as cash flow. The discipline is the product: landlords who spend the reserve in good years report excellent returns until two systems fail in the same winter. The planner's total replacement exposure figure — $44,000 on the default schedule — is the bill the reserve exists to meet.
Scale the result honestly across a portfolio. Four similar units need about $985 a month of reserves, not four times a number you rounded down. Shared systems change the maths in the other direction: one roof over a fourplex is one roof, not four, so enter the building's actual component list rather than multiplying a single-family schedule blindly.
The formula
Annual reserve per item = Replacement cost ÷ Lifespan in years. Monthly reserve = total annual reserve ÷ 12 × number of units. Total replacement exposure = sum of all replacement costs × units. If an item has R years of life remaining and you start from zero, the catch-up reserve is replacement cost ÷ R per year.
Worked example — try it on the calculator above
Worked example: one single-family rental, default schedule
Roof $12,000 ÷ 25 years = $480 a year. HVAC $8,000 ÷ 15 = $533. Water heater $1,500 ÷ 10 = $150. Appliances $4,000 ÷ 12 = $333. Exterior paint $5,000 ÷ 7 = $714. Flooring $6,000 ÷ 15 = $400. Plumbing $3,000 ÷ 25 = $120. Driveway $4,500 ÷ 20 = $225. Total replacement exposure: $44,000. Annual reserve: $2,956, which is $246.33 a month per unit. Own four similar units and the portfolio reserve is about $985 a month — a real line in the budget, which is precisely the planner's point.
Frequently Asked Questions
What lifespans should I use for major components?
Standard estimates from the NAHB and Bank of America life-expectancy study: asphalt shingle roof about 20 years, furnace 15 to 20, heat pump about 16, central air conditioning 10 to 15, water heater about 10, appliances 10 to 17 depending on the item, carpet 8 to 10. Climate and maintenance move these materially — treat them as planning guidelines, not guarantees.
Is CapEx the same as maintenance?
No, and conflating them understates costs. Maintenance is routine and small — repairs, servicing, minor replacements — often budgeted at about 5% of rent. CapEx is the large, infrequent replacement of whole systems. A property analysis needs both lines; many advertised cash-flow figures include neither correctly.
Can I deduct CapEx reserves on my taxes?
No — reserves you set aside are not deductible; you cannot deduct money you still hold. When you replace a component, the cost is generally capitalised and depreciated — residential structural components over 27.5 years straight-line under IRS Publication 527 — with exceptions under the de minimis safe harbour ($2,500 per item without audited financial statements) and the small-taxpayer safe harbour. Keep receipts and consult a tax professional.
How does CapEx change when I buy an older property?
It rises, because remaining lifespans are short. Estimate each system's remaining life during inspection and compute the catch-up reserve per item: a roof needing replacement in 4 years at $12,000 requires $250 a month from day one, not $40. Total the catch-up figures before buying — they are effectively part of the purchase price.
Estimates, not advice. This calculator provides educational estimates based on the inputs you enter and the assumptions shown on this page. It is not financial, tax or investment advice, and it cannot see your full situation. Verify important figures against official sources, and consider a qualified professional for decisions about your own money. See our Disclaimer and Methodology.