Application
Lift slab floating floor systems that incorporate spring isolator assemblies
to decouple concrete slabs from non-isolated structural floors are used
where vibration and impact are critical and of greater concern than airborne
noise transmission. In instances when vibration and/or impact noise control
are severe, the air space beneath the spring-isolated floor is vented.
This enables the composite construction to yield the lowest natural frequency
(fn) possible thereby enhancing performance against lower disturbing frequencies.
If additional control of airborne noise is needed for a vented floating
floor, the floor/ceiling composite will require partitions on the floating
floor at the perimeter and/or an isolated ceiling.
Representative examples of projects that can justify the use of spring
lift slab isolators are bowling alleys, weight rooms, gymnasiums, aerobic
activities, and dance studios. Spring isolators also are incorporated
into lift slab floors supporting sensitive measuring equipment in order
to mitigate vibrations that could compromise performance. While the bulk
of isolated slabs can be supported using fiberglass or neoprene pads,
most often in formwork systems, spring-isolated lift slabs are needed
for the most critical vibration and impact noise isolation requirements.
Typically, the Model LSM system supports a four inch (4") thick standard
weight (150 PCF) concrete slab using spring isolator mounts spaced up
to 54" on center. First, Perimeter Isolation Board (Model PIB) is adhered
to the perimeter of the floating floor area. Then, one (1) layer of 6-mil
thick poly sheeting is rolled-out across the structural slab and up Model
PIB, serving as a bond breaker between the non-isolated concrete structure
and the concrete floor being floated. Next, isolator mounts are located
and placed on top of the poly sheeting according to approved submittal
drawings. Isolator mount spacing and capacity can vary depending on load
requirements across the floating floor. Extra mounts may be required to
carry additional loads imposed by, for example, walls and heavy equipment
placed on the slab after it is lifted. Once the isolator housings are
in place, steel concrete reinforcement bars are used to interconnect the
mounts. Additional reinforcement as dictated by conventional concrete
slab design requirements may be required before concrete is poured level
to the tops of the mounts. Up to 30 days may be required for the concrete
to cure to strength. Once the concrete has cured properly, spring assemblies
are inserted into the housings and the slab is lifted to the specified
height. When the slab is lifted to specified height, the composite construction
typically includes a 1" or 2" air cavity. Complete installation guidelines
and isolator array plans and details are included in the project submittal
package.
Benefits
- Fabricated, non-cast isolator housings permit flexible
product and system design that maximizes application opportunities for
any slab thickness, air cavity, and/or load options.
- Spring isolator natural frequencies (fn) of 3.13 Hz
for 1" rated deflection springs and 2.21 Hz for 2" rated deflection
springs. Other rated deflection springs available.
- In-field acoustical testing yielded results of FIIC
72, FSTC 61 for a vented (non-vented floors can yield higher FSTC values)
floating floor.
- Spring/neoprene cup combination improves performance
against low-frequency noise.
- Proven effective for vibration isolation applications
ranging from floors for sensitive lab measuring equipment (e.g., metrology
and surgical labs) to sports floors over retail/commercial spaces.
- Factory installation and/or supervision available.
