21mm Karma Visco 21 Acoustic Overlay Board

21mm Karma Visco 21 is an acoustic overlay board designed to reduce the effect of impact and airborne sound passing through existing floors. These high performance acoustic floor boards are used for conversion projects where there is an existing floor surface and a shallow floor build up is required. This high acoustic performance is created by using internal strips of Visco elastic adhesive to dampen sound transmission and vibrations before it reaches the building structure. A cushioning foam layer absorbs any minor differences in the existing floor. Visco 21 boards are factory bonded so they can simply be laid over the existing floor.

• Excellent impact and airborne sound  performance,
• T&G edge profile for ease of installation,
• Can be laid directly on to existing floor,
  
• Ideal for refurbishment projects,
• Minimal height increases, which is ideal for refurb projects,
• Can be used with variety of floor finishes,
• Absorbs minor defects in existing floor,
• Saves labour and time,
• Can also be used on concrete floors.

• Refurbishment projects where there is a decking above the joists and a new acoustic ceiling,
• Where height restrictions exist but reliable performance is still required.
  

• Joist surfaces should be level prior to the start of installation. Place Karma isolation tape between Karma Visco overlay boards and perimeter walls during installation. This will reduce flanking sound transmission.
• Lay Karma Visco overlay boards as shown in the illustration with the grooved edges or cut edges facing the perimeter walls. Use the off cut from the final panel in the first row to commence the next row. Do not start a row with an off cut less that 250mm long. Lay panels in a brick bonded fashion.
• While laying boards apply a liberal amount of PU D5 adhesive to the grooves of the T&G joint and tightly butt the boards together. Wipe off excess adhesive with a damp cloth. Avoid walking on the boards until the adhesive has dried.
  

Note: Karma Visco overlay boards should be laid within rooms to maximise acoustic performance and not below partitions of any type. To prevent swelling or twisting ensure the boards are kept away from water and high humidity. If boards are affected by water they should be replaced. Boards should be kept inside, under cover and in dry conditions at all times. They should be stacked flat on a level surface and should be located into the environment in which they are to be fixed at least 24 hours prior to fixing.