We will now create our simulation. In any rigid body simulation, the objects have some properties that define them. For instance, you can set their mass, velocity, or simply let gravity act on them as the sole force. In any decent physics engine, you can have static and dynamic objects. A static object is an object that, as its name implies, can't move at all but will be considered in the simulation when collisions occur.
A dynamic object is an object that can receive forces. In Blender, static objects are defined as Passive and dynamic objects as Active.
We will select all our planks, and in the Physics tab, in the left 3D view panel (T), we will press the Add Active button. They will have a green outline.
Now we will set the ground object as passive by pressing the Add Passive button so that the planks don't pass through the house.
The Physics tab
In order to simulate our stack, we will launch the animation. To do this, we will use the Alt + A shortcut or press the Play button of the Timeline editor. Note that if the simulation doesn't seem to launch, you can replace the Timeline bar on the first key frame.
The final stack of wooden planks
As you may have seen, there is an orange line on the Timeline that tells us that a simulation has been cached, but as soon as you go backwards in time, the simulation will be removed. So after the simulation has been completed, we will have to apply the placement of each of the planks. In order to do this, we will select them and click on Apply Transformation in the Physics tab. We can now safely replace the Timeline bar at the first frame, and our stack will rest still.