Last lesson ended on a quiet warning: every production run adds about 1 percent wear to a building. This lesson is the full story of building health - how to make buildings bigger through upgrades, how that wear builds up and eventually bites, and how to repair it with renovation. Master this and your town stays strong for the long haul instead of slowly grinding to a halt. It is the difference between a town that keeps growing and one that quietly seizes up.
I want to frame this kindly, because the word degradation sounds alarming and it really is not. Wear is just the cost of a building doing its job, the same way a well-used tool needs sharpening now and then. None of it sneaks up on you if you know the two thresholds we are about to learn, and renovation is always there to wind the clock back. So read this as good housekeeping, not a looming crisis.
Upgrading a building
Upgrading raises a building one level, giving it more capacity and more output. The price follows the same friendly formula as building from scratch: a target level N costs N hours and 5 times N energy, plus materials. So upgrading toward level 4 costs 4 hours and 20 energy plus materials. But an upgrade has a few extra requirements beyond the cost, and all of them must be satisfied before it will run.
- You need free unskilled workers on hand to do the work.
- You need a road of the right level connecting the patch back to the City Hall.
- The building must be below 80 percent degradation to upgrade at all.
That last point is the one that surprises people, so let us be clear about it. A building that has worn past 80 percent degradation cannot be upgraded until you repair it. This is exactly why the roads and the layout you planned back in lesson 4 matter - an upgrade quietly checks for a proper road and for a building that is not too worn down. If an upgrade refuses to proceed, check those three things first, and the culprit will almost always be one of them.
Upgrades need a road and good repair
Before you can upgrade, make sure a road of the right level reaches the patch, you have free unskilled workers, and the building sits below 80 percent degradation. Miss any one of these and the upgrade will not go through.
One reassuring detail about that road requirement: an upgrade asks for a road of the level you are upgrading to, but roads themselves only climb to level 5. So the demand is capped there - a house going beyond level 5, all the way up to level 10, still needs only a level 5 road, never a level 6 one that cannot exist. Get the road serving a house up to level 5 once, and it will carry that house through every remaining upgrade.
How degradation works
Now the wear itself, told plainly. Every production run adds roughly 1 percent degradation. That sounds tiny, and run by run it is - but it adds up the way small things always do. There is a second source of wear too, and it runs on the clock rather than on your activity: time alone degrades a building by 3 percent each day, and roads more gently at 2 percent a day, whether or not you produce anything. Only the starting buildings and roads around your City Hall escape this - everything you raise afterwards needs upkeep. There are two thresholds that matter, and if you remember only one thing from this lesson, remember these two numbers. The first you just met: at 80 percent, upgrades become impossible until you repair. The second is harder: once degradation passes 95 percent, you cannot start any new production at all until you repair the building. At that point the building is essentially worn out and demanding maintenance before it will work again.
Two wear thresholds to watch
At over 80 percent degradation you can no longer upgrade. At over 95 percent you can no longer even start new production. Do not let a hard-working building drift up to 95 percent unnoticed, or it will simply stop earning until you fix it.
Renovation - the repair
Renovation is how you repair a worn building and push that degradation back down. There is a window for it: you can renovate once wear reaches 25 percent, and you can renovate all the way up to 100 percent. The cost scales with how degraded the building is - a lightly worn building is cheap to renovate, while a near-ruined one is expensive. So there is a real judgement call here, and it is one of the first genuinely strategic choices you will make as a mayor.
You might wonder when the best time to renovate is, and there is no single perfect answer - only sensible habits. Because cost scales with wear, letting a building rot to near-100 percent makes the repair pricey, but renovating constantly at 25 percent means paying often for small fixes. Many mayors settle into a rhythm of renovating before the building crosses the thresholds that block them - keeping it under 80 percent if they plan to upgrade, and well under 95 percent so production never stalls. There is no single right answer; just do not get caught unable to act when you most want to.
Two special rules to remember
Two facts round this out and tie back to things you already know. First, the level caps you learned earlier still hold: most buildings cap at level 5, while houses go to level 10. Second, schools are special to upgrade. Raising a school does not just need free unskilled workers like other buildings - it needs free trained professors. So if you want a higher-level school, make sure you have spare professors trained and available, not just generic labour. It is a small twist, but it catches the unprepared.
Schools want professors to grow
Upgrading a school requires free trained professors, not unskilled workers. Keep a couple of spare professors on hand if you plan to level your school, or the upgrade will stall for lack of them.
Let me tie upgrades and wear together into one simple mental routine, because together they are the rhythm of a healthy town. Upgrading is how a building grows up; renovation is how it stays young. Both ask for free workers, both reward the planning you did with roads, and both are blocked if you let wear climb too high. So the natural cadence is this: produce until a building has done real work, glance at its wear, and keep it healthy enough to do what you want next. If you mean to upgrade, keep it under 80 percent. If you only want it producing, keep it under 95 percent. Renovate when the cost is still reasonable, and your buildings will serve you for as long as your town stands.
I want to gently correct a worry that some new players carry, because it can make them too cautious. Wear is not a punishment for using your buildings, and you should absolutely use them. A building that produces and slowly degrades is doing exactly what it is for; a building you are too afraid to run is earning you nothing at all. Renovation exists precisely so that you can work your buildings hard and then refresh them, again and again, indefinitely. So do not hoard your buildings in pristine idleness. Run them, watch the two thresholds, repair when sensible, and let them earn. A well-used, well-maintained town vastly outproduces a timid one.
With upgrades, wear, and renovation understood, your buildings can grow and stay healthy indefinitely - there is no expiry date on a town that is cared for. Keep the two thresholds in mind, renovate before they bite, and you will never be caught out. The final lesson of this chapter turns from buildings to the people inside them: happiness, lifespan, and the surprisingly important art of keeping your workers alive.