In the Philippine context, "incremental housing"—the practice of building a home in stages based on available financial resources—is a socio-economic reality. However, the law does not exempt a structure from technical standards simply because it is being built piece-meal. All construction activities are governed primarily by Presidential Decree No. 1096, otherwise known as the National Building Code of the Philippines (NBCP), and its Revised Implementing Rules and Regulations (IRR).

1. The General Rule: No Permit, No Construction

Under Section 301 of the NBCP, no person, firm, or corporation shall erect, construct, alter, repair, move, convert, or demolish any building without first obtaining a building permit from the Office of the Building Official (OBO) in the municipality or city where the project is located.

For incremental builders, this means that even if you only intend to finish the ground floor this year and add a second floor three years later, the initial construction requires a permit based on the approved plans.

2. The Permit Process for Incremental Builds

When building incrementally, there are two primary legal paths a homeowner can take regarding permits:

Full Permit for the Final Design: The homeowner submits plans for the entire finished structure (e.g., a two-story house). The permit is issued for the whole project. While construction may stop once the first floor is habitable, the permit remains valid as long as construction is not abandoned for more than 120 days or if the work does not commence within one year from the date of issue.
Permit for Phased Construction: If the financial gap between stages is expected to be years, the owner may apply for a permit for "Phase 1" only. When the owner is ready to add more rooms or floors, they must apply for an Amended Building Permit or a new permit for Addition/Alteration.

3. Essential Requirements and Documentation

To secure a building permit for any stage of construction, the following documents are mandatory:

Proof of Ownership: Certified True Copy of the Original/Transfer Certificate of Title (OCT/TCT). If the land is not owned, a notarized Copy of the Contract of Lease or Deed of Absolute Sale.
Clearances: * Barangay Clearance for construction.
Locational Clearance from the Zoning Administrator.
Fire Safety Evaluation Clearance (FSEC) from the Bureau of Fire Protection.
Technical Documents (signed and sealed by licensed professionals):
Architectural Plans.
Structural Plans (crucial for incremental builds to ensure the foundation can support future floors).
Sanitary/Plumbing Plans.
Electrical Plans.
Mechanical Plans (if applicable).

4. Structural Integrity and "Future-Proofing"

One of the most significant legal and safety hurdles in incremental housing is Section 105 of the NBCP, which deals with site requirements and structural design.

If a homeowner builds a single-story structure with the intent to add a second floor later, the Structural Analysis submitted during the first permit application must reflect the load-bearing capacity for the eventual total height. If the initial foundation was not designed for a second floor, the Building Official will deny a permit for the addition later unless retrofitting is performed, which is often more costly than the original build.

5. The Role of the Certificate of Occupancy

A building permit is merely the "permission to build." To legally live in the structure at any completed stage, a Certificate of Occupancy is required.

For incremental builders, a Partial Certificate of Occupancy may be issued if a portion of the building (e.g., the ground floor) is safe and functional while the rest remains unfinished. This allows the homeowner to legally apply for permanent utility connections (water and electricity).

6. Exemptions for "Indigenous Individual Family Dwellings"

It is a common misconception that all small houses require full permits. Under the NBCP and Republic Act No. 7279 (Urban Development and Housing Act), certain exemptions or simplified processes exist for:

Traditional indigenous family dwellings: Houses made of native materials (bamboo, nipa, logs) with a total cost not exceeding PHP 15,000.00.
Socialized Housing: Projects under the government's socialized housing program follow the standards of Batas Pambansa Blg. 220, which provides more relaxed technical requirements compared to the NBCP to make housing more affordable.

7. Penalties for Non-Compliance

Building incrementally without the proper permits or deviating from approved plans can lead to:

Administrative Fines: Ranging from a few thousand pesos to a percentage of the structure's value.
Cease and Desist Orders: Immediate stoppage of construction.
Demolition Orders: If the structure is found to be dangerous or violates zoning laws (e.g., encroaching on setbacks), the Building Official may order its demolition at the owner's expense.
Criminal Liability: Under Section 213 of the NBCP, violations can lead to a fine of up to PHP 20,000 or imprisonment of up to two years.