Sawmill
The Sawmill is your in-city resource building that produces Wood for your account. Unlike Wood gathered from resource nodes on the world map, this Wood is a secured resource that cannot be pillaged in the event that your Town loses to an opponent’s attack.
The Sawmill is a highly important building in the early game since it will be your main source of Wood. Increasing the building level of the Sawmill does not directly upgrade its efficiency, but it does allow you to build more (and higher level) Furniture within the Sawmill building that increases its productivity as well as provide additional slots for Resident workers. This efficiency can be further enhanced with research in the Economy research tree of the Academy building.
Just like other resource buildings, resource gathering on the world map will start to outpace in-town resource generation due to diminishing returns of additional Sawmill levels, usually around the mid-20s of Town Center level. While the Sawmill never stops being an important source of this important resource, it does mean its priority can fall slightly behind other buildings you are upgrading if you have to make tough choices.
Sawmill upgrade costs (levels 1-30)
| Level | Prerequisites |  Wood |  Bread |  Stone |  Iron | Upgrade Time | Power |
|---|---|---|---|---|---|---|---|
| 1 | Defense Tower Lv. 1 | 30 | – | – | – | 2s | 40 |
| 2 | Town Center Lv. 2 | 45 | – | – | – | 3s | 76 |
| 3 | Town Center Lv. 3 | 200 | – | – | – | 10s | 130 |
| 4 | Town Center Lv. 4 | 450 | – | 90 | – | 35s | 202 |
| 5 | Town Center Lv. 5 | 1,900 | – | 380 | – | 1m 10s | 310 |
| 6 | Town Center Lv. 6 | 4,800 | – | 960 | 240 | 2m 20s | 472 |
| 7 | Town Center Lv. 7 | 17,000 | – | 3,400 | 865 | 4m 45s | 706 |
| 8 | Town Center Lv. 8 | 31,000 | – | 6,300 | 1,500 | 7m 10s | 940 |
| 9 | Town Center Lv. 9 | 65,000 | – | 13,000 | 3,200 | 10m 30s | 1,174 |
| 10 | Town Center Lv. 10 | 110,000 | – | 23,000 | 5,700 | 14m | 1,514 |
| 11 | Town Center Lv. 11 | 110,000 | 110,000 | 23,000 | 5,900 | 18m | 1,854 |
| 12 | Town Center Lv. 12 | 150,000 | 150,000 | 30,000 | 7,500 | 21m 30s | 2,194 |
| 13 | Town Center Lv. 13 | 210,000 | 210,000 | 42,000 | 10,000 | 26m | 2,768 |
| 14 | Town Center Lv. 14 | 280,000 | 280,000 | 56,000 | 14,000 | 33m 30s | 3,342 |
| 15 | Town Center Lv. 15 | 410,000 | 410,000 | 83,000 | 20,000 | 43m | 3,916 |
| 16 | Town Center Lv. 16 | 530,000 | 530,000 | 100,000 | 26,000 | 1h 13m | 4,724 |
| 17 | Town Center Lv. 17 | 830,000 | 830,000 | 160,000 | 41,000 | 1h 27m 30s | 5,532 |
| 18 | Town Center Lv. 18 | 1,100,000 | 1,100,000 | 220,000 | 56,000 | 1h 45m | 6,340 |
| 19 | Town Center Lv. 19 | 1,400,000 | 1,400,000 | 280,000 | 70,000 | 2h 38m | 7,488 |
| 20 | Town Center Lv. 20 | 1,900,000 | 1,900,000 | 380,000 | 96,000 | 3h 17m 30s | 8,636 |
| 21 | Town Center Lv. 21 | 2,400,000 | 2,400,000 | 490,000 | 120,000 | 4h 16m 30s | 9,784 |
| 22 | Town Center Lv. 22 | 3,200,000 | 3,200,000 | 640,000 | 160,000 | 6h 25m | 11,506 |
| 23 | Town Center Lv. 23 | 4,000,000 | 4,000,000 | 800,000 | 200,000 | 8h 59m | 13,228 |
| 24 | Town Center Lv. 24 | 5,400,000 | 5,400,000 | 1,000,000 | 270,000 | 12h 34m 30s | 14,950 |
| 25 | Town Center Lv. 25 | 7,300,000 | 7,300,000 | 1,400,000 | 360,000 | 17h 36m 30s | 16,672 |
| 26 | Town Center Lv. 26 | 9,400,000 | 9,400,000 | 1,800,000 | 470,000 | 20h 15m | 19,202 |
| 27 | Town Center Lv. 27 | 13,000,000 | 13,000,000 | 2,600,000 | 670,000 | 1d 0h 18m | 21,732 |
| 28 | Town Center Lv. 28 | 17,000,000 | 17,000,000 | 3,500,000 | 890,000 | 1d 3h 57m | 24,262 |
| 29 | Town Center Lv. 29 | 22,000,000 | 22,000,000 | 4,400,000 | 1,100,000 | 1d 8h 8m | 26,792 |
| 30 | Town Center Lv. 30 | 27,000,000 | 27,000,000 | 5,400,000 | 1,300,000 | 1d 14h 34m | 30,470 |
Costs and times shown are for that level only, not running totals.