What are immovables by destination?

Immovables by destination are those essentially movables but by the purpose for which they have been placed in an immovable, partake of the nature of an immovable [especially par. 4, 5, 6 & 9 of Art. 415 of the Civil Code].

What are the requisites of immovability by destination?

[1] The thing must be placed by the owner or by the tenant (as agent);
[2] With intention of attaching them permanently even if adherence will not involve breakage or injury.

Where the improvement or ornaments placed by the lessee are not to pass to the owner at the expiration of the lease, they remain movables for chattel mortgage purposes. (Davao Sawmill v. Castillo)

More principles:

[1] Immovability of property may also be based on its being destined for use in the industry or work in the tenement.
[2] The moment they are separated (from the immovable or from the industry or work in which they are utilized), they recover their condition as movables.
[3] If it is still needed for the industry but separated from the tenement temporarily, the property continues to be immovable.

Requisites for Immovability in Par. 5 of Art. 415 of the Civil Code:

[1] Placed by the owner or the tenant (as agent); and
[2] Adapted to the needs of the industry or work.

Estoppel despite Immovability by Destination due to Agreement

Parties may, by agreement, treat as personal property that which by nature would be real, as long as no third parties would be prejudiced. That characterization is effective between the parties. (Makati Leasing v. Wearever)What if the thing is attached to an immovable?

[1] Machinery becomes part of the immovable.
[2]The installation of machinery and equipment in a mortgaged sugar central for the purpose of carrying out the industrial functions and increasing production, constitutes a permanent improvement on said sugar central and subjects said machinery and equipment to the mortgage constituted thereon. (Berkenkotter v. Cu Unjieng)

What are the requisites of immovability by attachment to an immovable?

[1] Placed by the owner or the tenant (as agent);
[2] With the intention of permanent attachment; and
[3] Forming a permanent part of the immovable.

Immovability of Floating Constructions

[1] A floating house tied to a shore and used as a residence is considered real property, considering that the waters on which it floats are considered immovables.
[2] But if the floating house makes it a point to journey from place to place, it assumes the category of a vessel, and is considered movable