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What is Perlite?

Perlite Underfloor Insulation Specifications

Typical Sound Levels When Using Perlite Insulation

Application of Perlite in Underfloor Insulation

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Perlite for Underfloor Insulation

Why Perlite Insulation?

Perlite underfloor insulation is an inorganic product that does not rot, support combustion nor provide a habitat for rodents. Because of its neutral pH, the product does not foster corrosion in piping and electrical wiring that may be in the underfloor area.

When used for underfloor insulation, a water repellent, dust suppressed perlite specially produced for this application is used.

Underfloor Applications

Perlite underfloor insulation may be used under floating concrete floors, asphalt floors and floating board floors. It is especially useful when used to level floors and greatly reduces sound transmission from floor to floor, from floors to walls and from underfloor piping systems.

Floating Floors

Perlite underfloor insulation is most frequently used under floating concrete floors. In this application, perlite insulation is poured on the original floor surface, screeded to proper depth, covered with corrugated cardboard or lightweight boards, and a layer of oil paper. Oil paper must be used if a concrete floating floor is to be poured. A plastic film is used beneath the perlite to prevent seepage of material between cracks in floors and walls. Poured concrete floors, asphalt floors or wood floors can be laid over the insulation in a conventional manner.

This system is particularly useful when underfloor heating is employed as the insulation is dimensionally stable under varying temperatures and is not combustible. Perlite underfloor insulation as thick as 12 inches (30 cm) has been applied, but 2-4 inches (6-10 cm) is the normal. Underfloor insulation over 4 inches (10 cm) should be compacted. A unique feature of perlite insulation is that particles will interlock when pressed together and settling or volume changes will not take place.

Levelling of Floors

A special property of perlite is its ability to flow around any roughness, unevenness or exposed installations on the base floor. This enables the easy and rapid installation of level floors. In addition, because perlite underfloor insulation can be made to resist water penetration, it will not absorb or hold water permanently should there be a plumbing leak. This characteristic of perlite underfloor insulation will limit damage to a local area. As perlite is inorganic with a neutral pH, it will not corrode piping or electrical or communications conduits beneath the floor.

Sound Insulation

An area of increasing importance today is sound insulation. In construction there are three concerns: low sound transmission in construction components, low transmission between floors and walls and low transmission of sound from footsteps. Perlite underfloor insulation performs in much the same manner as multiwall systems with bulk insulation to achieve reductions in sound transmission.

With perlite underfloor insulation systems, sound transmission from floors to walls is reduced by using expansion strips at the intersection of floors and walls. Sound transmission from plumbing systems is also reduced when piping is surrounded by perlite insulation within the floor.

Information given herein is from sources considered reliable, but no guarantee of accuracy can be made or liability assumed.  Your supplier may be able to provide you with more precise data.  Certain compositions or processes involving perlite may be the subject of patents.
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