isostep-IG-impact-thnSoundproofing a floor requires addressing the issue of impact noise. Impact noise is a structure borne sound created when two objects collide. This impact energy creates vibrations that resonate through the materials in the structure. It also creates airborne sound that travels through the air. This is often realized in the real world as a ‘neighbor noise’ generated from someone walking on the floor above or other activities.

To short circuit the impact noise, an acoustic floor underlayment should be utilized. It must be placed underneath the finished flooring and cover the whole floor. This will prevent structural sound from passing through the completed assembly.

Iso-Step® Acoustic Floor Underlayment

Iso-Step® Acoustic Floor Underlayment, when installed correctly, is a double duty acoustical underlayment. It improves IIC ratings (Impact Insulation Class) by providing an impact resistant layer under flooring. This reduces the transmission of structure borne sound. Additionally, Iso-step® will add to the STC (Sound transmission loss) of the overall assembly.

IsoStep can be installed over wood or concrete sub-floor, beneath hardwood, vinyl, tile and carpet flooring. IsoStep Floor Underlayment is economically priced and available for quick shipment.

Typical Tools Needed for Installation:

toolsTape measure | Metal straight edge | White marker, chalk or chalk line | Utility knife | Duct tape (optional) | Other tools may be required to install subsequent layers of flooring materials.

Prep Work

Iso-Step® Underlayment and the flooring material to be installed must acclimatize, in their sealed packaging, in the room where they are installed for at least 48 hours, at a temperature of at least 65 degrees F. Before starting your installation of Iso-Step®, make sure the sub floor is permanently dry and free of dirt, dust, grease, and other foreign matter.

♦ Prep for Wood base: Subfloor should be properly leveled, structurally sound, and clean. Plywood subflooring should be of a good grade. Variations in floor level over 1/8″ within a three foot span should be leveled before installing underlayment. Any nails or other protrusions should be pounded flat or removed. Holes and other surface variances should be repaired prior to installation of IsoStep. To use the IsoStep with a nail down hardwood floor, it is recommended to create a “raft” made of 2 layers of 1/2” plywood , glued and screwed together with the top layer turned 90 degrees in orientation and offset by 2 feet from the edge in order to cover the seams. Leave a 1/2” gap between the wall and the raft to allow for expansion around the entire perimeter. Use 1-1/2” nails applied a an angle to secure the hardwood flooring on top.

♦ Prep for Concrete base: Inspect concrete sub floor for any open cracks and fill with high-grade epoxy filler. Remove any excess concrete lumps or residue that may interfere with the installation of Iso-Step®. If using a vapor barrier, a polyethylene sheeting is recommended. Install with overlapping seams (6-8″ overlap) using tape to secure edges. The vapor barrier should be applied directly over the concrete.

Floating Floor Systems

Under Laminate & Engineered Wood Flooring or Tile

Iso-Step® Floor UnderlaymentThe laminate or engineered wood flooring is intend to float on top of the Iso-Step® rubber floor underlayment. In most cases, acoustic underlayment may be installed in a few easy steps.

First install a perimeter isolation strip to prevent the flooring from touching the walls or any protrusions in the floor. Be sure all areas are prepped, level and free of dirt and debris. Then follow the installation guide as outline in the documents section of the Iso-Step® Floor Underlayment page and as instructed by the flooring manufacturer.

Under Tile
Iso-Step® Floor Underlayment - After installing a perimeter isolation strip, apply approved adhesive to the sub-floor using recommended trowel size.Iso-Step® Floor Underlayment - Roll out and lay the Iso-Step into the adhesive bond.Iso-Step® Floor Underlayment - Roll the Iso-Step with an approved flooring roller.Iso-Step® Floor Underlayment -Apply adhesive to the Iso-Step using recommended trowel size.Iso-Step® Floor Underlayment -Lay finish floor layer according to flooring manufacturer’s guidelines.

Nail Down Hardwood Flooring

Installation of solid nail down hardwood flooring using a raft method. Install IsoStep from wall to wall– loose lay; lay ½” plywood on top leaving a ½” expansion/acoustic gap around all walls. Install a second ½” layer of plywood making sure of stagger the bottom seam from the top, glue & brad nail the top plywood to the bottom plywood. The plywood floats on top of the underlayment, the nail down hardwood can be fastened into the plywood raft. The expansion gap can be left alone or filled with an acoustical caulk, install baseboard slightly off finished floor.

** Do not nail through Iso-Step® Underlayment.**

Other Articles on Soundproofing:

Soundproofing a Wall

Soundproofing a Window