4" Thick Slab Spring Lift Mount

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Lift slab floating floor systems that incorporate spring isolator assemblies to decouple four inch thick concrete slabs from non-isolated structural floors are used where vibration and impact are critical and of greater concern than airborne noise transmission.


Drawings | BIM



Isolator Components


Isolator Components - Explore in 3D

Installation Sequence


System Detail: Before Lifting



System Detail: Before Lifting - Explore in 3D

System Detail: After Lifting



System Detail: After Lifting - Explore in 3D

Perimeter Condition w/ Partition



Housekeeping Pad Options



Submittal Documents

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System Components






4" Slab, 2" Air Space 1" Spring Deflection

4" Slab, 2" Air Space 2" Spring Deflection

Isolator Components

Installation Sequence

System Detail: Before Lifting

System Detail: After Lifting

Perimeter Condition w/ Partition

Housekeeping Pad Options

Additional Documents





Installation Overview



    Adhere resilient interface (PPI by KNC) to all penetrations and perimeters.  PPI prevents sound vibration from transferring from the isolated slab to the non-isolated structure.


    Cover entire floor with bond breaker (Poly Sheeting by KNC).  This ensures that the isolated slab can be lifted into place.


    Place Canisters with Wooden Lid per engineered shop drawings (by KNC or KNC Representative).  Caulk or tape to bond breaker, preventing concrete from leaking beneath Canister.


    Install concrete reinforcement per project drawing and design specifications.


    Pour concrete and allow to cure.  Remove and discard wooden lid and screws.


    Grease Lifting and Leveling Screws.  Place Spring Assembly into cavity per engineered shop drawings.  Balance Steel Lid on Leveling Screw, insert and engage (do not tighten) Lifting Screws.


    Drive Lifting Screws two or three turns for each isolator in sequence until floor is raised.   Trim perimeter bond breaker and remove PPI tear strip.  Apply sealant in gap.

Time Lapse Video

Design Guidelines


  • “My Acoustical Consultant selected LiftWrx for use on my project, what is the first step?”

    Contacting your Local Representative is a good place to start. You may find the Design Phase Timeline helpful as an overview of typical activities.

  • “What information is included in your shop drawings?”

    Our shop drawings include coordination of the live and dead loads, a dimensioned isolator layout with capacities, acoustical information capacities, acoustical information including deflection of individual isolators, as well as project specific and general installation guidelines for the contractors.

  • “What information is needed for Kinetics to create shop drawings?”

    The timely gathering of essential information makes difference in our turnaround time. A guide for helpful information can be found here.

  • “Should isolated floor drawings be in the Structural or Architectural plans?”

    As isolated slabs are by their nature non-structural, they typically reside in the Architectural Plans.

  • “What structural concerns are there?”

    Ensure that the structural slab has the proper depression to include the isolated slab as well as the airspace created after the slab is lifted. Structural slab stiffness and capacity considerations must be made relative to the activity of the floor (e.g. if the floor activity is to include the drop of heavy, a stiffer structural slab is required). The existing floor should be flat as the isolators can only mirror the floor on which they are resting. If there are seismic concerns, designing a curb capable of restraining the isolated slab will eliminate the cost of using in-slab restraints.

  • “Who should design the rebar spacing in the isolated slab?”

    If your project isn’t employing a structural engineer of record, then slab design should go to an independent third party firm to avoid any potential conflict-of-interest with isolator layout. Kinetics maintains relationships with independent structural engineering firms experienced in isolated slab design who can seal the reinforcement design in all fifty states.

  • “Help! The contractor just finished raising the floor and it is sticking up past the surrounding elevation!”

    Kinetics selects spring capacities and isolator spacing based on many factors, including but not limited to, even deflection between adjacent isolators, (limits concrete slab stress) the type of activity that will be occurring on the isolated slab, as well as the total live and dead loads that will be on the slab. In some cases the slab may need to be raised above the room threshold, but will settle to proper height once all the loads are added.


Design Phases

Isolated Floor Seismic Restraint

Structural Floor Flatness



  • FF = 38 (SOV)
  • FF = 25 (MLV)
  • Kinetics requires a specified overall value of Floor Flatness FF = 38 and a minimum local value of Floor Flatness FF = 25. This means that locally the floor is considered “Flat” and globally the floor is considered “Good” (“Flat” and “Good” are terms defined by ACI- American Concrete Institute Guidelines Section 302). Conventionally this means locally a 10 foot straight edge would have 1/4 inch of variation, and globally the variation would be less than 3/16 inch.
  • These requirements are necessary for Kinetics spring lift slabs because the top of the structural floor becomes a pouring form for the bottom of the isolated slab. As the canisters are a fixed height, inconsistencies in the structural floor become reflected in the isolated slab. If the structural floor is not considerably flat then issues can arise that adversely affects the acoustical, and even possibly the structural performance of the isolated, elevated slab. The standard deviation of varying thickness of the slab could be significantly more than was accounted for in the selection of the isolators; this could lead to under or over isolation, incorrect leveling screw set dimensions, and structural stress in the isolated slab. This can also make lifting the slab to a constant elevation very difficult.
  • Normally FL is typically specified with along with these numbers for levelness. While flatness between mounts is critical, the slope of a floor is not nearly as crucial. Please contact Kinetics if a sloped floor is being considered with spring isolated slabs.

Construction Documents Content Guide



  • Architectural/General: Floor plans
    • Note whether the isolated slab area is one single isolated slab, or divided into multiple isolated slabs and/or non-isolated infill areas.
  • Section Details
    • EOS (edge of slab) conditions and transitions
    • Airspace under the slab (typically 2")
    • Housekeeping pads or other areas of thicker concrete
  • Loading Data Clarifies which walls sit on the isolated slab, and which walls sit on the structural slab.
    For walls that sit on the isolated slab, provide:
    • Partition plan
    • Partition schedule
    • Partition heights
    • Load path and load (in pounds or KIPS) of any stationary equipment, millwork, etc.
    • Load path and weights of any operable partitions/curtains, seating, equipment, etc.
    • Identify and provide equipment and materials with their respective weights that may be moved on floor during or after construction.
  • Structural:
    • Framing plan and/or edge-of slab plan
    • Restrictions/requirements of isolator spacing, if any (typically 48" on center each way)
    • Type of concrete (normal weight, lightweight, etc.)
  • Acoustical: From Acoustical Consultant, if applicable
    • 1" or 2" Spring deflection
    • Minimum Spring Deflection
    • Damping Information
    • Venting Details

Proven effective for intense impact applications ranging from floors for sensitive lab measuring equipment (e.g. metrology and surgical labs) to sports floors over retail/commercial spaces.

Spring isolators natural frequencies (fn) of 3.13 Hz for 1" rated deflection springs and 2.21 Hz for 2" rated deflection spring. Other rated deflection springs are available.

Factory-engineered shop drawings detail consider spacing, spring load/deflections and structural floor flatness requirements.

Rubber cap assembly protects against resonant frequencies.

In-slab or perimeter seismic restraint elements available where required.

Springs ship in ready-to-install sub-assemblies.

Castings are stocked ready to ship.