Buildings
Every building Timber Empires adds, by what it’s for. Most have a version for each faction: the infobox on each page has a tab for each. Costs for all of them side by side are in Reference.
Walls and towers
Palisade A wall of sharpened logs that blocks the way for everyone. 
Wall A solid wall of iron-banded planks that blocks the way for everyone. 
Gatehouse A fortified gate with stairs up to the wall walk. Shuts when enemies or bandits come near. 
Log Hoarding A gallery on the wall where warriors roll logs down at enemies, knocking over everyone in their path. 
Oil Hoarding A gallery on the wall where warriors pour boiling canola oil on enemies below. 
Wall Tower Joins walls on any side and leads up to the wall walk. Sees far through the fog, further from high ground. 
Ballista Tower A wall tower with a ballista on its deck. With a crew aboard, it shoots the nearest enemy in reach on its own, with a little extra range from its height. 
Trebuchet Tower A wall tower with a small trebuchet on its deck. With a crew aboard, it lobs stones at the nearest enemy in reach on its own, far past the wall. Siege machines
Field Infirmary A healing tub on wheels for after a battle. Once no enemy is in sight, wounded troops take turns lying in it and heal fast while its doses last. A dose is 1 extract and 2 berries. Its crew only moves it. Only warriors can build it. 
Field Ladder Lets your warriors and carters climb a one-level step. Only warriors can build it. 
Field Ramp A long timber ramp up a one-level step for warriors, carters and siege machines. Only warriors can build it. 
Battering Ram Batters the wall, gate or dam in front of it, faster with more warriors aboard. Only warriors can build it. 
Siege Tower Rolls up to a wall and lets the warriors aboard out onto its walk. Only warriors can build it. 
Catapult Hurls stones at a chosen target, hurting enemies and battering walls and siege engines. Its crew moves and aims it. Only warriors can build it. 
Ballista Shoots heavy bolts flat and far: deadly to enemies, weak against walls. Its crew moves and aims it. Only warriors can build it. 
Trebuchet Hurls siege stones at a chosen target, hurting enemies and battering walls, gates and siege engines. Needs warriors aboard to turn and throw. Military buildings
Forge Makes the basic kit troops train and fight with: swords, spears, bows, slings and shields. 
Armory Makes battle axes for berserkers. 
Gunsmith Makes arquebuses and blasting charges. 
Barracks Trains its workers as troops: warriors, spearmen, or the faction's own kind. 
Archery Range Trains its workers to shoot from a distance: archers, or the faction's own kind. 
Monastery Trains monks. Instead of fighting, they convert enemy troops and siege machines to your side, then wait for their faith to return. 
Wagon Yard Sends supply carts to the front so warriors can eat, drink and build siege engines off the roads. 
Stone Press Presses scrap metal and logs into siege stones for catapults and trebuchets. Water mines
Mine Workshop Makes water mines from explosives and metal blocks. 
Mine Slipway Releases floating mines that drift with the current and explode against the first building they hit. 
Moored Mine A mine anchored in the water. Goes off when a boat or a drifting mine comes close. 
Fireship Dock Launches boats packed with explosives that sail up the river and blow up against the first building or mine they hit. 
Mine Net Floats in the river and catches drifting mines. Lay several end to end to make a barrier. 
Net Winch Its worker rows out to the linked nets and brings back caught mines for reuse. Territory and trade
Watchtower Claims the land around it while its brazier burns, so other players can't build there. Reaches further from high ground. Sends an automation signal while enemy troops are on its land. 
Power Exchange Sells power from one district's network to the district across the border. 
Trading Post Trades goods with the district across the border at a fixed rate. 
Toll Tube Station Lets your beavers ride another district's tubeway for a toll. 
Toll Station Lets your beavers ride another district's ziplines for a toll. 
Troops Counter Counts your troops that are ready, in training, deployed, fighting or wounded. In district mode, it counts the troops of the district's barracks and ranges, wherever they are.