How much to budget for maintenance and capital expenditure
The percentage rules of thumb come out at half what a component-by-component estimate does, and the components are the ones that actually break.
The short answer
Split routine maintenance from capital replacement and budget them separately. Routine maintenance is fine as a percentage of rent; capital items are not, because they are large, predictable and arrive on their own schedule. Costing each component over its life typically produces a figure well above the common rules of thumb.
The formula
annual reserve per component = replacement cost / expected life in years
total capex reserve = sum of all component reserves
monthly reserve = total / 12
as a share of rent = total / annual gross rent
Expected life, not warranty length. A roof warranted for fifteen years and lasting twenty-five should be reserved over twenty-five, and a boiler in a hard water area may not reach its rated life at all.
Worked example
A single-family rental at $2,150 a month, costing each major component over its realistic life:
roof 12,000 / 25 = 480 · HVAC 6,495 / 15 = 433
water heater 1,400 / 10 = 140 · kitchen 11,000 / 20 = 550
two bathrooms 14,000 / 20 = 700 · flooring 5,496 / 12 = 458
exterior paint 4,200 / 8 = 525 · windows 9,000 / 30 = 300
total capex reserve = 3,586 a year = 298.83 a month
as a share of gross rent = 3,586 / 25,800 = 13.9%
Nearly fourteen percent of rent, before a single routine repair. The 8% rule of thumb covers maintenance and calls it both, which is why capital items feel like disasters rather than schedule.
Why capital items should not be a percentage
A percentage of rent has no relationship to when a roof needs replacing. It produces a number that feels prudent and bears no connection to the actual liability sitting on the property.
It also scales the wrong way. Two identical houses in different rental markets would reserve very different amounts under a percentage rule, while their roofs cost the same.
The component method takes an hour once and is then just arithmetic. It also tells you which item is next, which is the part that changes decisions.
Where the reserve should live
In a separate account, transferred monthly, in the same way as tax. A reserve that exists only in a spreadsheet is not a reserve, it is an intention.
It also changes how a large repair feels. Replacing a $6,495 HVAC out of a reserve that has been building for nine years is a scheduled event. Replacing it out of the current account is a crisis, and it is the same $6,495.
Adjusting it for the property you actually own
An older property does not need a higher percentage, it needs shorter remaining lives on the components. A twenty-year-old roof with five years left reserves at 12,000 divided by 5, not by 25, and that single change is often the difference between a comfortable model and a wrong one.
Get a survey to establish remaining life on the big three: roof, heating and windows. Everything else can be estimated within a useful margin.
New builds are the mirror image. Almost nothing needs replacing for a decade, and the temptation is to reserve nothing, which just moves the whole liability to year eleven.
What this leaves out
- Replacement costs are illustrative and highly regional. Component lives are more stable than component prices.
- Excludes tenant damage beyond a deposit and excludes insured events, both of which are separate provisions.
- Assumes like-for-like replacement. Upgrading during a replacement is a capital improvement rather than a reserve draw.
This arithmetic is free to run in your browser — no signup, nothing held back.
Open the free calculatorCommon questions
- Is the 1% rule for maintenance accurate?
- One percent of property value a year is a reasonable order of magnitude for routine maintenance and it does not cover capital replacement. Treating it as covering both is the reason capital items feel like surprises.
- What if I self-manage and do repairs myself?
- Your labor lowers the cash cost and not the material cost, and a roof is not a weekend job regardless. Reserve for the components either way, because the day you stop doing the work the liability is unchanged.
- Should the reserve reduce my reported cash flow?
- Yes, if you want cash flow to mean anything. A property showing positive cash flow while under-reserving is borrowing from a future repair, and the loan always comes due.
Spreadsheets that do this
The formulas above, already built and checked — so you fill in your numbers rather than the arithmetic.
Related guides
Last reviewed 22 August 2026