Firewall

Firewall - A firewall (also known as a fire-resistant wall) is a fire-resistant wall that prevents the spread of fire between buildings or sections of a building. According to the Bavarian Building Code (Art. 28 BayBO), it must have a fire resistance rating of at least 90 minutes (REI 90 / F 90-A) and be constructed of non-combustible materials. Fire walls are mandatory at property lines, for building distances of less than 5 meters, and as interior building partitions in large buildings.

Requirements and Design

The BayBO sets the following requirements for fire walls:

• Fire resistance class: At least REI 90 (load-bearing) or EI 90 (non-load-bearing) made of non-combustible building materials - in practice, masonry at least 24 cm thick or reinforced concrete at least 20 cm thick
• Roof overhang: The fire wall must extend at least 30 cm beyond the roof surface or terminate with a fire protection solution of equivalent effectiveness (upstand)
• No openings: Fire walls must not have any openings (windows, doors) under any circumstances. Exceptions are permitted only with self-closing, fire-resistant closures (T90 doors)
• Side closure: At the building’s exterior walls, the fire wall must be flush or project 50 cm

When is a fire wall required?

• Building boundary wall: At property lines or where the distance to the property line is less than 2.50 m
• Internal fire wall: In buildings exceeding 40 m in length, internal fire walls must divide the building structure into sections
• Townhouses/semi-detached houses: The shared wall between the two halves of the house must be constructed as a fire wall

Fire Safety in Energy-Efficiency Renovations

During energy-efficiency renovations of existing buildings, fire safety requirements often conflict with insulation measures: If exterior thermal insulation is to be installed on a fire wall, it must not compromise the fire wall’s properties. Combustible insulation materials (EPS, polystyrene) must not be used on fire walls-non-combustible mineral wool insulation is mandatory there. The fire wall must extend beyond the roof surface even after insulation is installed. Anyone unaware of these requirements risks costly demolition following a building inspection.

Fire Wall Requirements According to BayBO - Overview

Situation	Fire wall required?	Fire resistance class	Legal basis
Building on property line	Yes (building boundary wall)	REI 90 / F 90-A	Art. 28 BayBO
Distance from property line < 2.50 m	Yes	REI 90	Art. 28(2) BayBO
Row houses (shared wall)	Yes	REI 90	Art. 28(3) BayBO
Building length > 40 m	Yes (internal fire wall)	REI 90	Art. 28(4) BayBO
Garages on property line	Exemptions possible	F 30 (exception)	Art. 28(7) BayBO
Opening / door in fire wall	Only with T90 door	REI 90 with closure	Art. 28(8) BayBO

Practical Tip for Property Owners in Nuremberg and Franconia

We recommend that property owners in the Nuremberg metropolitan area have the condition of existing fire walls inspected during renovation or remodeling projects. Particularly in Wilhelminian-style apartment buildings in Gostenhof or the Südstadt, fire walls have often been weakened over the decades by openings, retrofitted utility lines, or window installations. In the event of a change of use or an expansion, the building authority may require the restoration of fire protection-which can incur significant costs. When purchasing older apartment buildings in Nuremberg, we recommend having a structural engineer assess the fire protection status before the purchase price is finalized.

Frequently Asked Questions

Can I create an opening in a fire wall after the fact?

Creating an opening in a fire wall-such as for a doorway between two apartments-is only permitted with fire safety compensation: The opening must be fitted with a self-closing, fire-resistant closure (T90 door). Additionally, a building permit is generally required. The cost of installing a T90 door, including installation, ranges from 2,000 to 4,000 euros-plus permit fees. We recommend having the fire wall’s status confirmed by an expert before planning any openings.

How can I tell if a wall is a fire wall?

Fire walls consist of solid masonry or reinforced concrete and are generally at least 24 cm thick. They extend the full height of the building and protrude above the roof. Firewalls are marked separately on building plans. A building inspector can confirm the fire-resistant properties on-site. For older buildings without complete building plans, an on-site inspection is essential-not every solid wall is automatically a firewall under building code regulations.

How much does it cost to repair a damaged fire wall?

The costs depend on the extent of the damage. Sealing individual openings with fire-resistant masonry or fire-rated panels costs approximately 500-2,000 euros per opening. If the fire wall needs to be renovated across multiple floors, the costs can range from 10,000 to 30,000 euros. The installation of a T90 door, including installation, costs approximately 2,000-4,000 euros. In historic buildings where the fire wall is part of the historic preservation designation, the costs for restoration measures in accordance with preservation standards can be significantly higher.

What is the difference between a fire wall and a fire-resistant wall?

In common parlance, fire walls and fire-resistant walls are often used interchangeably; however, in the context of building regulations, there is a difference: A fire wall (Art. 28 BayBO) is a particularly high-performance fire-resistant structure of class REI 90 made of non-combustible building materials that permanently prevents the spread of fire between buildings or sections of a building. In practice, the term fire-resistant partition also encompasses room-enclosing walls with lower fire resistance classes (e.g., EI 30 or EI 60) that form fire compartments within buildings but do not meet the requirements for true fire walls. For property owners, this distinction is relevant if the term is used in the purchase agreement or in an expert report-only a fire wall as defined by the BayBO provides the legally required maximum protection at property boundaries and between building sections.

Fire Safety Retrofits in Existing Buildings in Nuremberg

In renovation projects involving Nuremberg’s Wilhelminian-style buildings, which are often densely clustered together, fire safety retrofits present a major challenge. Many of these buildings have fire walls dating from the late 19th or early 20th century that were subsequently used for utility lines (gas, electricity, water) or window openings. During building permit proceedings-such as for additions, changes of use, or energy-efficient renovations-the Nuremberg Building Authority may require the restoration of the original fire protection level. Anyone purchasing such a property should have the fire safety status checked as part of the technical due diligence. A fire safety engineer can quickly assess whether and to what extent retrofitting measures are necessary-and estimate the associated costs.

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