Gate Toughness: The Toughness of the main gate. The number in parentheses is the Armor rating.
Wall Toughness: The strength of the outer defenses and central keep. Each wound crates a 1” gap in the defenses.
Siege Bonus: This modifier is added to the defending general’s Battle Rolls and acts as a Morale modifier for the defenders. It includes defensive weapons, like boiling oil.
Defenders: The usual number of guards on duty at any one time. It takes far fewer men to protect a fortification than to capture it. If the defenders have warning on an impending attack, double this number.
Supplies: The number of weeks of provisions stored in the fortification. If the defenders have time to prepare for a siege, this number is doubled.
Cost: Prices are included as a guide for GMs. Characters should seek permission from the landowner before embarking on a construction project.
Concentric castles are the pinnacle of castle design. In the center is a turreted keep (often round to limit the effectiveness of bores) protected by a stone wall. Beyond this lies the barracks, workshops, and stables. These ware also protected by a curtain wall, usually with several round turrets along their length. Beyond this lies a deep moat. Truly large concentric castles may have as many as three or four circles, each protected by a fortified gatehouse and curtain wall.
Gate Toughness: 24 (4); Wall Toughness: 50 (20); Siege Bonus: +4; Defenders: 400; Supplies: 52; Cost: $200,000
Fortified Manor House
Usually home to knights or wealthy landowners, fortified manor houses are two story stone structures with no outer defenses, save maybe for a low ditch. Workshops, stables, and barracks are contained in separate outbuildings. Despite being relatively unprotected, the walls are thick enough to withstand an assault without siege weapons.
Gate Toughness: 15 (4); Wall Toughness: 20 (10); Siege Bonus: +1; Defenders: 10; Supplies: 6; Cost: $10,000
Hill forts are built primarily as a refuge for the locals in times of war. In larger hill forts, permanent villages may exist. Hill forts lack strong defensive walls, instead being constructed of concentric ditches and high earth banks, topped with a wooden palisade. The main entrance is blocked by a gate, and protected by a small maze of earthworks, designed to break up the enemy advance.
Gate Toughness: 22 (4); Wall Toughness: 35 (15); Siege Bonus: +2; Defenders: 200; Supplies: 20; Cost: $60,000
Large castles comprise a central keep (usually square), a large courtyard containing stables, workshops, and barracks, a high curtain wall protected at the corners with towers, and a moat.
Gate Toughness: 24 (4); Wall Toughness: 40 (20); Siege Bonus: +3; Defenders: 200; Supplies: 26; Cost: $140,000
Motte and Bailey
Motte and bailey castles are the first true castles as commonly depicted in fantasy games. They consist of a small keep or tower, usually on a hill, surrounded by an earth bank with a wood or stone wall on top. Larger versions are divided into two, with barracks and workshops on the lower level, and the keep on a second level, surrounded by its own wall.
Gate Toughness: 15 (2); Wall Toughness: 25 (10); Siege Bonus: +1; Defenders: 20; Supplies: 12; Cost: $35,000
A small castle comprises a central keep, usually square, a small courtyard area containing workshops and barracks, a stone curtain wall, and a moat.
Gate Toughness: 22 (4); Wall Toughness: 35 (20); Siege Bonus: +3; Defenders: 50; Supplies: 26; Cost: $85,000
The forerunner of the motte and bailey, a stone tower lacks the defensive earthworks. Usually standing 20 to 30 feet high, with several levels inside, they may be home to a wizard or a poor knight.
Gate Toughness: 15 (4); Wall Toughness: 20 (10); Siege Bonus: +1; Defenders: 10; Supplies: 4; Cost: $7000
See the fantasy gear toolkit for more on siege warfare.
Half the cost of fortifications is the labor cost, while the other half is materials that must be either obtained or purchased. If natural resources are available, additional time and labor can be substituted for the material costs.
For ease of calculation use the defender numbers as the number of skilled builders required. Twice that many laborers are required. Laborers cost 10 silver a month while skilled builders cost 50 silver a month. Once you add the labor costs up, divide those monthly costs from the total labor cost to get the number of months it would take to build. This can be cut by one quarter of the time by doubling the laborers and builders.
Example: A tower has 3500 silver in labor costs. At 10 defenders, it has 10 builders, and 20 laborers per month for a monthly cost of 700 silver. It will take 5 months to complete.