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Thermal
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Using a 'k'-value of 1.83 for dense concrete, a 250mm thick solid concrete slab using OMNIDEC will achieve a u-value of over 2.92W/m²K
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However, by the addition of polystyrene void formers to the precast panel (OMNICORE), this value reduces to 1.324W/m²K for a typical 60/40% spilt of polystyrene/concrete.
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Infill Portion with Polystyrene
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th |
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'k' value |
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'y' value |
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Outer wall surface |
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0.065 |
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In-situ concrete |
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0.065 |
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1.830 |
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0.036 |
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Polystyrene |
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0.135 |
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0.037 |
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3.649 |
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Precast concrete |
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0.050 |
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1.830 |
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0.027 |
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Inner wall surface |
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0.140 |
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'r' value 3.916 m²K/W |
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'U' value 0.255 W/m²K |
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In-Situ Portion
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th |
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'k' value |
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'y' value |
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Outer wall surface |
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0.065 |
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In-situ concrete |
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0.250 |
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1.830 |
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0.137 |
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Inner wall surface |
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0.140 |
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'r' value 0.342 m²K/W |
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'U' Value 2.927 W/m²K |
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Ratio of 60/40% Polystyrene/Solid
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With Polystyrene |
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60% |
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0.255 |
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0.153 |
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Solid |
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40% |
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2.927 |
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1.171 |
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average 1.324 W/m²K |
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Omnitherm
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The resistance to thermal transmittance of both OMNIDEC and OMNICORE can be enhanced by the addition of up to 25mm of insulating material (e.g. Styrofoam) to the soffit during the manufacturing process.
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Depth |
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Omnidec |
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Omnicore |
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incl 25mm Styrofoam |
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200mm |
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3.182 |
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1.495 |
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0.498 |
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250mm |
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2.927 |
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1.319 |
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0.445 |
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300mm |
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2.711 |
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1.195 |
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0.412 |
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Sound
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The reduction of sound transference through a horizontal slab requires solutions to both airborne and impact transmittance.
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Both solutions rely on some extent on the density of the slab construction, and similar to the solution to the thermal transfer, on the characteristics and arrangement of the constituent materials.
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Reduction of airborne sound
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The ability of a floor to reduce the passage of airborne sound is directly related to the density of the structural slab.
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The building regulations require concrete floor slabs to be either 365kg/mē (when finished with a Type 1 floor) or 300kg/mē (Type 2 floor).
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The depths of OMNIDEC and OMNICORE required to achieve the minimum requirements with both types of floors are:
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Type 1 floor |
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Type 2 floor |
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Omnidec |
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160mm |
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150mm |
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Omnicore |
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260mm |
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200mm |
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Reduction of impact sound
|
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Resistance to impact sound depends mainly on a resilient layer and the type of floor coverings.
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Horizontal transmittance of sound through party walls will be overcome by the inclusion of a cavity wall. However, this may effect the structural capabilities of the floor by reducing continuity of the slab.
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