An apartment floor is the horizontal structural element separating two dwellings located above one another, engineered to meet stringent requirements for load bearing, fire resistance and sound insulation.
Unlike a standard intermediate floor within a single dwelling, an apartment floor forms a legal and physical boundary between independent homes. This imposes higher performance demands governed by building regulations.
Key requirements
Sound insulation
Noise transmission between apartments is one of the most common sources of complaint in multi-unit buildings. An apartment floor must limit both:
- Airborne sound — voices, music and television. Measured as the weighted sound reduction index (Rw or DnT,w). Typical regulatory minimums range from 52 to 55 dB.
- Impact sound — footsteps, dropped objects and moving furniture. Measured as the weighted normalised impact sound pressure level (Ln,w). Lower values indicate better performance; requirements are typically 54 dB or less.
Fire resistance
Apartment floors must act as fire-separating elements, preventing the spread of fire and hot gases between dwellings for a defined period. Common requirements are 60 minutes (REI 60) or 120 minutes (REI 120), depending on building height, use class and national regulations.
Structural capacity
The floor must carry permanent loads (self-weight, screed, finishes), imposed loads (furniture, occupants) and any partition loads. Typical design imposed loads for residential apartments are 1.75 to 2.0 kN per square metre.
Common construction types
- Reinforced concrete slab — cast in situ or precast hollow-core planks. Provides excellent mass for sound insulation and inherent fire resistance.
- Composite steel-concrete deck — steel profiled sheeting with a concrete topping, often used in steel-framed apartment buildings.
- Timber-concrete composite — timber joists or CLT panels combined with a concrete topping to improve acoustic performance.
In all cases, a floating screed on a resilient layer is commonly added to achieve the required impact sound insulation.
Related terms
- Floating screed
- Sound insulation (Rw / Ln,w)
- Fire resistance rating (REI)
- Hollow-core slab