How to build a multi-year maintenance plan for your house

A multi-year maintenance plan lists what your house is made of, how old each part is, and what each part needs, then puts a cost and a due year against each job. That turns a calendar of work into a number you can budget against. In the Netherlands it is called a meerjarenonderhoudsplan, or MJOP.

The document is a list of systems, and the list is closed

The document begins by breaking the house into parts, because a house is not one thing that wears out. It is roughly 22 systems on separate clocks, running from about 10 years to 200: a smoke detector is spent at 10, load-bearing masonry can stand for two centuries. The plan is the list of those systems with an age, a next date and a cost against each.

Working from a closed list is what makes this finishable. Without one, there is no way to know when you are done: walking around the house with a notebook, you will write down the tap, the cupboard, the third window on the landing, and stop somewhere arbitrary, not because you were careless but because nothing told you where the edges were. A fixed set of 22 has an edge. Go through the list asking “do I have this, and what kind is it,” and you reach the bottom. Twenty-two is smaller than a professional element list because it is grouped at system level, not at the level a surveyor pins individual observations to. The full 22 are listed in How long a house lasts, with the expected life of each.

Where to start, and where to stop

The systems that carry the money are the roof, the windows, the heating and the wet rooms: between them they carry the largest single bills, and they are the ones you can answer accurately from what you can see and what you remember.

Start there. Then stop.

A plan that is 60 per cent right today is worth more than a complete one you never finish: the incomplete plan is already telling you which years are heavy and what your monthly budget is. The rest fills in as you live in the house, as every repair you log, every service you book and every inspection you commission sharpens it.

Write down what you know today. Correct it the next time a repair, a service or an inspection tells you it was wrong.

What to note against each line

For each system, write down what kind it is, how old it is, what it costs today, and the year it falls due.

Put exterior paint on the line of what it protects: the exterior joinery, the cladding. Planned that way, it becomes one cycle across all of them in a single visit rather than a front door done this year because it looked tired and the windows three years after that. Give interior paint its own line: it wears with use rather than weather, so plan it on its own cycle, roughly 12 to 16 years.

Put windows, external doors and skylights on one line, under a system called openings, so it carries a rotting sill, a new set of shutters, a shattered pane and a door that has dropped on its hinges.

Where neither you nor a look around the house can settle something, such as what the foundation is made of or what is behind the bathroom tiles, write “unknown” and name what would answer it: a foundation survey, a look at the last renovation record. Do not guess. A guess about the most expensive part of the house is a confident claim you cannot back up; an honest gap is not.

For each line, take the cost of the job, a quote you have, or the cost guides on this site (the middle of the band if you have a range), divide it by the years until it falls due (count one year for anything due now), add the lines up, and divide by 12: that is the monthly figure, in today’s money. A plan run on the same lines moves it in both directions. One pot that funds whichever job falls due first comes out no higher than this line-by-line sum: for each year, add up the jobs due by then, divide by 12 times the years until that year (one year for anything due now), and keep the largest. Indexing the later years’ costs and adding a 25% allowance to each big job’s typical cost, for access, making good and what turns up once the work is open, push it higher. Which way it lands depends on how the jobs are spread across the years.

Condition, and the honest limit of what you can judge

Your plan runs on age against expected life, which is what professional plans use for anything a surveyor has not looked at. The best professional plans combine that baseline with regular maintenance surveys to sharpen the short-term picture; that precision takes investment and training you are unlikely to have, and the baseline itself is what mid- and long-term planning runs on regardless.

What stands in for that short-term precision is a version of how professionals model wear over time. A component runs quietly to around half its expected life, degrades measurably from there, and enters end-of-life at about three quarters: the two-inflection curve professional wear models run on.

Those two inflection points, and the thresholds behind them, derive from Dutch condition-assessment practice. Whatever a surveyor did not reach is planned on its cycle, not scored, and running that across the whole house applies the same method more broadly, not a different one.

Damage does not reverse: stopping a leak halts further decay but does not give back the life already lost, so a year deferred past the midpoint is a year the component will not return. The right moment to buy an inspection is when the plan says a big year is coming, which is where professional judgement pays for itself.

What an inspector knows that a homeowner learns late

One useful thing a maintenance plan does is connect jobs that look unrelated. A surveyor does this without thinking about it. Without the dates side by side, a homeowner finds out afterwards, and it is where avoidable money goes.

Some things can only be seen while something else is open. The upper face of the roof structure, the battens and the underlay are visible only when the covering comes off, once in 15 to 100 years depending on the covering. If the covering is being replaced, that is when the timber underneath gets looked at. Miss it and the next opportunity is a full cycle away.

One job drags in another. Changing a gas boiler for a heat pump is not a swap of the box: a heat pump runs at a much lower flow temperature, so radiators sized for a boiler are usually too small, and the pipework may not be adequate either. Rewiring means chasing walls, which means replastering and redecorating; people budget the electrician and meet the decorator at the end.

Access is one cost serving several jobs. Scaffolding put up for the roof also reaches the gutters and the high windows. Three jobs in one visit cost less than the same three in three separate years, because the access is paid for once, which is why a professional plan groups by access rather than by urgency wherever possible.

And a failure in one place shows up as consequential damage in another. A blocked gutter puts water down the wall until the wall is a problem and eventually the structure is. A wet room with inadequate extraction shortens the life of its waterproofing well below the 20 to 30 years it should give. Neither shows up as a cost against the thing that caused it.

You are not expected to work any of this out. What the plan gives you is the dates side by side, which is the part that is hard to hold in your head: a flat roof due in 2031 and pointing due in 2032 are two lines on one page rather than two problems arriving a year apart. Seeing them together is enough. The question you put to a contractor is whether doing both in one visit costs less than doing them separately, and that is a question any of them can answer.

Where this departs from professional practice

An event that revises your plan can also be a choice: stretching a component’s life a year or two past its expected end, knowingly rather than by accident. Pooling instead of ring-fencing avoids a cost: with one pot, money set aside for a job years out covers the job that falls due first, so the same monthly amount reaches further; ring-fenced lines each hold money that cannot be used until their own date, which over-reserves on a single house. Starting today rather than at installation means the remaining cost is spread over the years left rather than the full life. And because the room is not on the plan’s clock, a kitchen is replaced when someone living in the house wants a different kitchen.

The waterproofing behind the tiles carries a hard cutoff of its own: in the Nordic markets many insurers limit or decline water-damage cover for wet rooms older than about 30 years.

Every number in a plan is a forecast. Lifespans are averaged across brands, across differences in output and in how a part gets used, then rounded to a figure that is easy to calculate with, generally a multiple of five, unless the source gives a shorter, harder figure: a manufacturer’s replace-by date, a warranty term, a repaint cycle, a trade replacement cycle.

Costs are given as bands because nobody knows how the market will develop, how regional scarcity will affect price, or how technology will change the cost of skilled labour, parts and replacement. Indexation of forward costs, at 2.5% a year in the plan, sits a little above long-run general inflation because construction costs have run above it over the last decade.

The part of your monthly budget set aside for big jobs is calculated to cover every foreseeable big job, not only the ones due soon: a roof due in 40 years is being saved for from now, spread across the years until it is due, because a fixed saving window only moves the cliff somewhere you cannot see it.

A worked example

Roos owns a 1974 terraced house in Utrecht. She works through the 22 systems on paper, one line each: what kind, how old, what it costs today and when it comes due.

Most lines she can fill from what she can see and remember. Some lines she leaves open, and says why: what the foundation is made of cannot be told by looking at the house, and a municipal archive drawing may or may not say; many owners never find out, so she writes “unknown” there, as above. What is behind the bathroom tiles is unknown too, but the one question she can answer is when the bathroom was last done: 2006, which puts the waterproofing at 20 years, inside its expected range of 20 to 30 but no longer young.

She adds the flat roof over the kitchen extension as its own line; the 22 systems do not carry it separately.

What she has after that is a dated document: she can see which years are heavy, and on paper the flat roof over the extension, due in 2031, and the rear pointing, due in 2032, fall within a year of each other. One scaffold reaches both, and scaffolding is a fixed cost of the job, paid once when the jobs share it rather than twice across separate years. Dating jobs like these across the whole plan is what turns years of EUR 0 followed by EUR 3,000 into a steadier EUR 600 to EUR 1,000 a year of planned spend (see corrective vs preventive maintenance). She would not have seen any of that from two separate quotes arriving a year apart.

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Related guides

• Corrective vs planned maintenance: the difference that decides what your house costs you: the two modes the plan schedules between.
• When to hire a building inspector: the point where a survey sharpens the plan’s forecasts into observations.
• How long a house lasts, part by part: the full map behind the 22 systems.

Glossary terms used in this guide

• Glossary: Component: the unit the plan is built around.
• Glossary: Corrective maintenance: the mode the plan schedules against.
• Glossary: Planned maintenance: the mode the plan puts jobs into.
• Glossary: Consequential damage: the cost a plan catches before it compounds.
• Glossary: Two-inflection curve: the degradation model the plan’s condition reading runs on.
• Glossary: Estimate: a contractor’s expected price, and how far the bill may run past it.

Where appkeep fits

Building the list above by hand works, and some homeowners will. In appkeep you start from a first draft: answer a country, a house type, a year built, a floor area, the number of storeys, three questions about heating and what has recently been replaced, and an optional set of answers (what the outside walls are made of, and counts of chimneys, bedrooms, kitchens, bathrooms and separate toilets), and the plan comes back with a draft across the main systems, built from what a house like yours usually contains. You never start from a blank page. The guesses the plan is least sure of are listed for you to confirm, and every row can be corrected: confirm what is right, fix what is wrong, remove what you do not have. Not every guess is right: it may assume double glazing where the house has already gone triple. Floor area and the number of chimneys are answers you give directly, and each one you confirm sharpens the plan. The window count is worked out from the floor area you enter, and you can set the real number on the plan.

The shift from corrective-default to planned-default does not happen by trying harder. It happens because the plan is on hand the day a question becomes a decision.