How to budget maintenance costs (a simple buffer)

Maintenance costs are “lumpy”: you can have months with nothing, then a big bill. A monthly maintenance buffer turns lumpy costs into a predictable budget line, so your affordability maths reflects real life.

Last updated: 2025-12-17

Built by Brandon

Methodology

Try the maintenance buffer in the calculator

Opens the main calculator prefilled so you can see how a buffer changes total shared cost, leftovers, and stress tests.

No signup. Private. Links are shareable and can be reset anytime.

Use the calculator with these defaults Open the calculator

What the buffer protects you from

The buffer isn’t just for “worst case” disasters. It covers predictable-but-irregular costs: replacing appliances, minor repairs, servicing, painting, garden upkeep, and the things you only notice once you own the place. Without a buffer, your monthly plan can look comfortable right up until it becomes stressful.

A good buffer is one you can sustain every month without feeling punished. Start modest, then adjust after 6–12 months based on reality.

Worked examples: buffer vs no buffer

These examples keep everything the same except the maintenance buffer.

Example 1: no buffer (looks cheaper than reality)

Maintenance buffer: £0 / month · Total shared: £2,936

Leftovers (proportional): A £1,895 / B £1,369

Open this scenario in the calculator Stress test the plan

Example 2: realistic buffer (£200/month)

Maintenance buffer: £200 / month · Total shared: £3,136

Leftovers (proportional): A £1,779 / B £1,285

Open this scenario in the calculator Stress test the plan

How to agree the buffer as a couple

Start with a number you can sustain (even if it’s not perfect).
Treat it as a shared housing cost and split it using the same rule as the rest of the shared costs.
Review after 6–12 months and adjust up or down based on reality.

FAQ

Is a maintenance buffer really necessary?

It’s one of the most useful realism upgrades you can make. Without it, your “affordable” plan can break the first time you need a repair or replacement.

How much should we set aside per month?

It varies by property type and age. The safest approach is to pick a number you can actually sustain and then adjust it over time as you learn your real costs.

Should the buffer be split the same way as the mortgage?

Usually yes, because it’s part of housing. But if one person is taking responsibility for repairs/DIY, you might choose a custom split — what matters is agreeing it explicitly.

What about service charges or ground rent?

If you have regular monthly charges, treat them like a shared housing cost too. The key is to include the recurring costs that affect monthly affordability.