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Building Augmentations & Fortifications

The possible list of augmentations for buildings as a whole are almost limitless. Below are some of the most common augmentations.

Mobile Buildings

This building can move, either by walking, rolling, hovering, flying, swimming, teleporting, or even across the planes. The following table shows the base speed of each movement type, how much it costs to add the type of movement to a building, and any additional information or restrictions which apply to the type of movement. A building may have multiple movement types added, each one must be paid for separately, but only one may be used at any one time. It is also possible to increase the speed of a movement type, with the cost of each additional 10 feet of movement given in the table.


Benefit(s) the building isn’t usually noticed by casual observers

Create 320 magic or 1000 goods, 600 labor; Time 32 days

This building is hidden from view, whether through invisibility or more mundane means (such as being cleverly designed to look like the surrounding terrain).

A DC 22 Perception check will allow someone to notice that the building is there, otherwise it goes unnoticed.

Every additional 32 magic or 100 goods and 60 labor increase the DC by +1.


Benefit(s) teleportation into and out of the building is impossible

Create 1,280 magic (128,000 gp); Time 128 days

It is not possible to use spells of the teleportation sub-school into or out of this building (it is possible to teleport from one place to another within the building, however). Any augmentation providing a teleportation effect (such as a teleportation circle) that allows travel outside the building costs 50% more than normal. This extra cost must be paid, even if this augmentation is added later.

Table 1-3: Mobile Building Cost and Speed
Type Base Speed Cost Speed Increase (+10 feet) Notes
Walking 30 ft. 700 magic (70,000 gp) 300 magic (30,000 gp) Cannot enter water greater in depth than the height of the building
Rolling 40 ft. 850 magic (85,000 gp) 500 magic (50,000 gp) Cannot enter water greater in depth than half the height of the building
Hovering 0 ft. 300 magic (30,000 gp) N/A Does not reduce speed due to terrain and may pass over water. Maximum altitude is 30 feet.
Flying 30 ft. 1,000 magic (100,000 gp) 600 magic (60,000 gp) Clumsy maneuverability, may hover at any altitude.
Swimming 30 ft. 700 magic (70,000 gp) 300 magic (30,000 gp) Floats on the surface of the water unless the building has the environmentally sealed augmentation
Teleporting Special 4,480 magic (448,000 gp) N/A CL 16 1/day, greater teleport
Planar-travel Special 2,000 magic (200,000 gp) N/A CL 10 1/day, plane shift


Benefit(s) this building appears to be something it isn’t

Create 200 goods, 150 labor; Time 60 days

This building appears to be something else, usually another kind of building. A DC 22 Knowledge (local) check is required to determine the actual purpose of the building. Every extra 20 goods, 15 labor spent adds +1 to the DC.


Benefit(s) small items may be easily moved from floor to floor without someone having to carry them

Create 120 magic (12,000) or 7 goods, 15 labor (220 gp); Time 12 days

A dumbwaiter is a small elevator system commonly used to transport food or small items between floors of a building. A tiny or smaller creature can fit into a dumbwaiter’s compartment without difficulty, but larger creatures are unable to do so (however they may be able to use the shafts for hidden movement within the building).

A mechanical dumbwaiter requires maintenance, just like an elevator, costing 2 goods and 5 labor (70 gp) every 6 months.

Replacement of the system, if needed, takes 2 days.


Benefit(s) a method moving from one floor of the building to another without using stairs

Create 240 magic (24,000 gp) or 15 goods, 30 labor (450 gp); Time 24 days

This represents either a mechanical (pulleys, ropes or cables) or a magical (levitation or flying) elevator system. An elevator takes 1 round to ascend or descend a single floor (multiple floors take multiple rounds, and a move action to select a destination.

A mechanical escalator system requires regular maintenance to ensure it keeps running smoothly.

Every 6 months, 5 goods and 10 labor (150 gp) must be spent on maintenance, or there is a cumulative 5% chance per month that the system will break and require replacement for the full cost. Replacement in this manner takes 4 days.

Environmentally Sealed

Benefit(s) effects, weather, and spells cannot penetrate the building.

Create 2,000 magic (200,000 gp); Time 200 days

An environmentally sealed building functions like an environmentally stable one, but also prevents any environmental effects penetrating the building. This means that the exterior of the building (including any windows) blocks line of effect for all spells of the conjuration (creation) subschool and prevents such spells effects from entering the building unless physically carried by a living creature. This means that (for example) cloudkill cannot pass through open windows, and the building provides air for the inhabitants even underwater or in a vacuum.

Environmentally Stable

Benefit(s) the interior of the building is comfortable, regardless of outside conditions

Create 80 magic (8,000 gp); Time 8 days

The building magically maintains a comfortable temperature and climate for the inhabitants, regardless of the environmental conditions outside.


Benefit(s) the building exists on a plane of its own.

Create 190 magic (19,000 gp); Time 1 day

This building is in its own demi-plane. The entrance to the building must clearly be a doorway or archway, and the entrance must not be accessible from any other direction (for example, the doorway to the demi-plane could be the front door to a large blue box but couldn’t be the archway at one end of an alley). Passing through the door transports any creature into the demiplane, which follows the rules of the lesser create demiplane spell. More powerful demiplanes, using create demiplane (217 magic (21,700 gp)) and greater create demiplane (241 magic (24,100 gp) may be constructed.


Like rooms, buildings may have a spell augmentation.

This costs twice as much as a room augmentation of the same spell, but a building may only have a single spell augmentation applied to it. This limitation does not prevent all rooms in the building being given the same spell augmentations. Anyone inside the building is affected by the spell augmentation when they enter the building, with spell resistance and any saving throws being attempted once when the creature first enters. The effect ends immediately when a creature leaves the building.

Fortified Buildings

Fortifications are defensive constructions that help the defenders of a building when it is under attack. They do not provide any benefits to the rooms within the building but affect how the building is used in siege warfare or if an army (or even a group of adventurers) attack it. The rules in this subsection describe creating fortifications using goods, labor, and time using the downtime rules.

Permanent vs. Temporary Fortifications: Fortifications can be permanently emplaced, in which case they always provide their benefits and drawbacks, or temporary, which speeds their construction significantly, but also reduces their effect – each type of fortification has separate statistics depending on whether it is permanent or temporary.

Difficult Terrain


Create 3 goods, 2 labor; Time 4 days


Create 1 good, 1 labor; Time 1 day

Most often a temporary fortification when a known attack is imminent, difficult terrain slows the advance of attackers and makes it impossible to make effective charges. It can take many forms, such as digging up the ground, scattering rubble around, or placing sharp plants in the way. Regardless of the exact method chosen, the effect on attackers is the same. Each difficult terrain fortification affects a 10- foot by 10-foot area and makes it difficult terrain for attackers. A successful DC 15 Knowledge (engineering) check can negate the fortification. Doubling the cost of the fortification increases the DC by 5, and this may be done multiple times, doubling the cost each time.

Having a section of permanent difficult terrain that cannot be easily avoided on the approach to a building reduces the furnishings quality of all rooms in the building by 1 step.


Create 2 goods 4 labor; Time 2 days

A moat is a trench (see above) that has been made effectively watertight and filled with water. A moat may only be constructed as a permanent fortification. Moats are usually significantly wider than they are deep, and can be built to house dangerous wildlife and plants.

A moat can be avoided in the same way a trench can.


Create 1 labor; Time 1 day

A wall of packed earth, a rampart is half the height but the same thickness as a normal wall. It has double the hit points of a sod wall and is immune to damage from ranged siege weapons. A rampart may include a palisade, a wooden wall atop it with half the normal height, hp, and SP of a normal wooden wall.


Benefit(s) attackers must travel further to get to the entrance of the building


Create 10 goods, 5 labor; Time 5 days


Create 5 goods, 3 labor; Time 1 day

A switchback is a carefully constructed artificial modification to the lines of approach to the front door of a building, effectively increasing the distance required to travel as attackers approach the entrance.

Each switchback affects a 20-foot wide section of the building’s exterior and extends 20 feet away from the building. Multiple switchbacks can be placed to extend the distance away from the building that is affected.

A temporary switchback doubles the distance required to move in a straight line towards the building, while a permanent switchback triples it. A basic switchback only affects large or smaller creatures. Huge creatures can be affected if the switchback extends at least 3 switchback sections away from the building, Gargantuan creatures if it extends 4 sections away, and Colossal if it extends 5 sections away. Flying creatures are not affected by switchbacks unless the building and fortification are underground.

For the purposes of other game rules, a switchback fortification does not count as difficult terrain, nor does it affect the speed of creatures in it, but it is not possible to charge through a switchback.


Create 1 goods, 3 labor; Time 1 day

A trench is a section of ground (20 feet long, 5 feet wide, and 10 feet deep) that has been dug out to present a difficult barrier for attackers to circumvent. Almost all trenches have one or more straightforward paths to allow easy access to the building (an exception might be a temporary trench dug all the way round a besieged building which has a reliable source of food and water for the inhabitants), which represents a potential weak spot in the fortification (that path is likely to be heavily guarded by other means).

Wider and deeper trenches may be constructed by constructing additional trench fortification sections adjacent to the existing sections but must be at least as many sections wide as they are deep.

Flying attackers are not affected by trenches, and it may be possible for attackers to effectively circumvent trenches with Acrobatics checks to jump across them.


Create See materials for goods, 1 labor (modified by materials labor factor); Time 1 day (modified by material’s time factor)

A defensive wall may be constructed in the same manner as any other wall and has appropriate statistics to match.

It is common for defensive walls to be built with shelter and raised platforms for defenders to stand within, to allow them to make ranged attacks against attacking forces from positions of relative safety.

Flying attackers may avoid a wall by the simple method of flying over it, but until they have crossed the wall’s position, the defenders still retain any advantages they have.

Walls do not have to be built a full 10-feet high – it is not uncommon for walls to be built 3- or 5-feet high, costing 1/3 and 1/2 the cost of a normal wall segment respectively, and requiring a similar proportion of time.

10-foot wall segments can only be built as permanent fortifications, but shorter segments can be temporary or permanent. The decision to make a wall temporary instead of permanent has no effect on the cost to create the wall, but temporary walls take 50% extra damage from siege weapon attacks and can be removed at no cost (but 1 day of time, regardless of material) later.

As with buildings, permanent wall fortifications may be constructed with windows.

It is common for a gatehouse room to be added to a permanent wall fortification.

Other rooms may be added at the GM’s discretion.

Building Location

Where a building is and how far away it is from the resources to build it (whether labor or materials) can drastically affect the cost of a building.


Every hex (or 12 miles if not using hex-based mapping) away from the nearest settlement adds 20% to the labor cost of a building.


The terrain in which a building is being constructed can affect the cost of materials – use the lowest applicable multiplier for the terrain and material being used.

Table 1-4: Material Cost by Location
Terrain Cost Multiplier (within hex) 1 hex (12 mi.) 2 hexes (24 mi.) 3 hexes (36 mi.) 4 hexes (48 mi.) 5 hexes (60 mi.) Notes
Plains 1 1 1 1 1 1
Hill 0.8 0.8 0.9 0.9 1 1 Applies to stone and metal materials only
Desert* +0.1
Forest 0.75 0.8 0.85 0.9 0.95 1 Applies to wood materials only
Marsh* +0.2
Mountain 0.75 0.8 0.85 0.9 0.95 1 Applies to stone and metal materials only
Cavern** 0.5 Applies to stone and metal materials only
Water*** +0.5

Notes: A suitable terrain improvement (commonly mine, quarry, or sawmill) provides a -0.1 multiplier

5 hexes of river, lake, or sea count as 1 hex of distance due to the ease of transporting goods on water (divide the water distance by 5, rounding down).

*: Desert and Marsh terrains are difficult to build on, and materials are almost always imported.

**: A cavern is considered to always be at least 1 hex away from any other source of material.

***: This is to actually build underwater, not just in a hex that has a river in it.

Section 15: Copyright Notice

Ultimate Strongholds © 2018, Legendary Games; Authors Ben Walklate and Jason Nelson.