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How to Build Firewall: Standards and Requirements in the Philippines

How to Build Firewall: Standards and Requirements in the Philippines

Planning to build a firewall for your home? Do it right. Learn the standards and legal requirements for firewalls in the Philippines to keep your property protected.

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The Good Home Daily

Build and Repair, Project DIY
Last Update: April 28, 2025

In 2015, a massive blaze in Nelsonville, Ohio, destroyed the historic Hocking College Art Gallery and the Hocking Valley Museum of Theatrical History, causing $597,000 in damages. Miraculously, the adjacent Stuart’s Opera House was spared, thanks to a brick firewall, sustaining only smoke and water damage.

In 2022, a fire in South Cotabato razed properties worth PHP1.8 million. While one house was completely destroyed, an adjacent property equipped with a firewall sustained only partial damage.

These incidents highlight the critical role of firewalls in protecting lives and property. A firewall is a fire-resistant barrier within a building that prevents or slows the spread of fire and smoke.

Unfortunately, due to a lack of awareness or prioritization, many overlook the importance of firewalls during construction. This guide covers everything you need to know about firewall standards in the Philippines.

What exactly is a firewall, and how does it protect your property? What are the legal requirements for constructing one in the Philippines? Let’s delve into the details.

What is a Firewall in Construction?

In a nutshell, a firewall is a fire-resistant barrier designed to prevent the spread of fire within a building. As defined by Republic Act 9514, the Fire Code of the Philippines, a firewall is “an exterior wall designed to prevent the spread of fire, having a fire-resistance rating of not less than four (4) hours with sufficient structural stability to remain standing even if construction on either side collapses under fire conditions.”

However, the Department of Interior and Local Government (DILG) has expanded this definition in Memorandum Circular No. 2021-064 to include both an external wall and a wall subdividing a building that can prevent the spread of fire.

This broader interpretation aligns with international standards, such as those set forth by the National Fire Protection Association (NFPA).

It’s crucial to distinguish firewalls from fire barrier walls and fire partitions. While all three are fire-resistant, firewalls are unique in their structural independence. They are designed to stand alone, creating separate fire compartments within a building. This characteristic is paramount in protecting occupants from the catastrophic collapse of a burning structure.

By compartmentalizing a building, firewalls significantly reduce the risk of fire spreading, allowing for safer evacuations and more effective firefighting efforts.

6 Key Things to Remember in Building a Home Firewall in the Philippines

Constructing a firewall in the Philippines requires strict adherence to the National Building Code of the Philippines (PD1096) and the Fire Code of the Philippines (RA 9514). Here are the key requirements to remember to comply with the country’s firewall codes and regulations.

1. Fire Resistance Rating

As mentioned, Firewalls must have a minimum fire resistance rating of four (4) hours, as mandated by the Fire Code of the Philippines. This means the firewall must be able to withstand fire for at least four hours without structural failure or excessive heat transmission.

2. Rules on Firewall Openings

Firewalls that separate properties must be solid and unbroken, with no openings except for specific ventilation systems. These walls should extend at least 400 to 1000 millimeters above the roof.

Any existing openings in firewalls must be completely sealed to prevent fire from spreading to neighboring buildings. This includes windows, air conditioners, and other similar features, as they can weaken the firewall’s protection.

To maintain the firewall’s integrity, only fire-resistant glass blocks are allowed. Firewalls built on property boundaries define property lines, and any additions or structures attached to them are illegal.

3. Wall Thickness Requirements

Perimeter and exterior walls must meet specific thickness requirements for fire safety and structural integrity:

Perimeter walls should be at least 6.5 inches thick, composed of a 6-inch reinforced concrete hollow block (CHB) wall with a half-inch plaster layer on the inside.
Exterior walls should be at least 7 inches thick, consisting of a 6-inch reinforced CHB wall with half-inch plaster layers on both sides. However, for practical reasons, a 4-inch thickness is often used for the exterior half of the wall.
Firewalls made of 6-inch CHBs should have at least a three-quarter-inch plaster layer on each side.

4. Rules on Natural Lights and Ventilation

For natural light and ventilation, Light and ventilation wells may be installed near firewalls under strict conditions. Operable windows within two meters of the firewall are not permitted for fire safety and privacy reasons.

5. Building Footprint with Firewalls

For buildings with firewalls, the footprint is measured from the property line to the opposite exterior walls. The specific rules depend on the number of firewalls and the building type:

Low-Density Residential (R-1)

Absolutely no firewalls are allowed, except for a small, non-structural abutment for a carport.

You can, however, build a short, abutment to 3.2 meters high to support a carport roof, but it must have openings and be no longer than 7 meters or half the length of your property line, whichever is shorter. This wall must be made of special concrete blocks and should not block too much sunlight from your neighbor’s property.

Medium-Density Residential (R-2)

Only one (1) firewall is allowed for houses in medium-density areas. You can build a firewall along up to 80% of one side of your property. But remember, you can only have a firewall on one side of your house.

High-Density Residential (R-3)

For high-density residential areas, two (2) types of firewall construction may be permitted:

Firewalls on two sides: You can build firewalls along most of both sides of your property, but not more than 65% of the whole property’s edge. Your building can only be two stories tall.
Firewall on one side and back: You can build a firewall along up to 90% up to 90% along one side and the back of your property. If the back of your property is only 4 meters wide, you can build a firewall along the entire back. But remember, you can only have firewalls on one side of your property, and your building can only be two stories tall. The back firewall can only be 3.2 meters high.

Townhouses (R-4)

Firewalls are allowed on both sides of each unit. These firewalls can be as long as 85% of each side of your property, but their combined length must not exceed half the total perimeter of your property. Your townhouse can be up to three stories tall, and all firewalls must follow safety rules.

Condominiums (R-5)

For condominiums (R-5), there are also two (2) options for building firewalls:

Firewalls on two sides: You can build firewalls that cover up to 75% of each side of your property, but their combined length must not exceed half the total perimeter of your property.

2. Firewall on one side and back: You can build a firewall along up to 65% of one side and 50% of the back of your property. The total length of both firewalls can’t be more than 60% of your property line. Your building can be up to eight (8) stories tall, but the back firewall must not exceed 14 meters in height.

6. Rules Regarding Roofline

According to Section 10.2.14.4 of the Revised Implementing Rules and Regulations (RIRR) of the Fire Code of the Philippines, firewalls were required to extend from the foundation to a point at least 760 mm above the roof surface.

However, under the proposed 2021 amendment by the DILG, firewalls may now terminate at the underside of a non-combustible or limited-combustible roof assembly—provided it meets specific fire resistance standards and other criteria. The exact requirements vary depending on the building type and materials used. Refer to Section 4.3 of the DILG’s amendment.

Firewall Construction: Leave it to the Experts

Building a firewall is not a DIY project. It requires specialized knowledge and adherence to strict building codes to ensure safety and compliance. Attempting to build a firewall yourself can lead to severe consequences, including life-threatening risks.

Beyond the physical dangers, you may also face legal repercussions if your firewall doesn’t meet the required standards. To protect your property and avoid potential legal battles, it is crucial to hire a qualified professional to handle the construction of your firewall.

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How to Build Firewall: Standards and Requirements in the Philippines

Table of Contents

What is a Firewall in Construction?