Architect and Builder March 2021 | Page 66

Myths About Insulation Performance

Insulation is growing in popularity and importance as its ability to improve the energy efficiency of buildings is recognised . But with that popularity comes some confusion about how it should be used to best effect . In the second of two features about the myths surrounding insulation , Suria Ramnarain , Sales Development Manager at Knauf Insulation looks at performance .

MYTH : Non-combustible materials provide a certain period of fire resistance TRUTH While non-combustibility and fire resistance both assess how a material or system performs in a fire , they are very different measures .

Non-combustibility is determined by tests that look at a material or system ’ s Reaction to Fire . These tests assess how it contributes to the development and spread of fire , whether or not it will ignite or produce smoke and whether it produces flaming droplets . This is crucial during the early stages of a fire to allow safe evacuation .
In South Africa , SANS 10177 part 5 measures the combustibility of materials and SANS 10177 part 10 assesses spread of flame . Our Glass Mineral Wool Ceiling Roll ( Multi Pack ) has achieved the best possible SANS 10177 parts 5 and 10 A / A1 meaning it is non-combustible .
In Europe , all CE marked insulation materials are assessed by the more stringent Euroclass Reaction to Fire Classification and given a rating from F ( combustible ) to A1 ( non-combustible ).
Unlike other common insulants , most Glass and Rock unfaced Mineral Wool products are non-combustible with the highest possible Euroclass A1 Reaction to Fire Classification rating . This means they will not contribute to the development or spread of fire should it occur . Where fire safety is concerned , why take the risk ? Non-combustible insulation such as Glass and Rock Mineral Wool is the safest option .
Fire resistance measures the ability of a system or construction to withstand fire , maintaining its form , function and structural integrity and preventing fire spread from one distinct area to another ( known as compartments ).
It is the whole system ’ s ability to resist fire for a stated period of time ( i . e . 30 minutes ) that is qualified through fire testing and assessments . Therefore , a material within the overall tested system cannot offer a period of fire resistance on its own .
MYTH Any insulation can be used to reduce noise TRUTH Different insulation materials perform in different ways . Insulation with closed cell structures such as rigid foam boards have very limited sound absorption qualities . By comparison , Mineral Wool is highly sound absorbent , which makes it very good for acoustic insulation .
But not all Mineral Wool performs the same way – for example , Ceiling Roll offers excellent thermal performance but does not provide the same level of sound insulation as Acoustic Roll , which has been specifically engineered for this purpose .
MYTH Only Rock Mineral Wool should be used for sound insulation TRUTH Many people think the higher the density , the better the sound insulation . But our latest research shows Glass Mineral Wool reduces noise as well as Rock Mineral Wool in certain applications and outperforms it in others .
Tests were conducted using a standard internal wall build-up comprising a metal stud partition at 600mm centres . Installing a specialist acoustic Glass Mineral Wool product resulted in a 44.8 dB DnTw reduction in sound . Swapping to a higher density Rock Mineral Wool insulation saw a sound reduction of 43.9 dB DnTw and increasing density again , a 41.0 dB DnTw reduction . In this application , the Acoustic Glass Mineral Wool roll provided better sound insulation than a Rock Mineral Wool slab would have .
Remember , the higher the density , the higher the cost . So , in this application , Acoustic Glass Mineral Wool provides better sound insulation and is more cost effective .
WHY MINERAL WOOL INSULATION ?
Sound waves are deflected between individual wool strands , similar to a pinball , converting sound energy to heat energy
Mineral wool insulation offers a unique combination of acoustic , thermal , fire and environmental performance
GLASS MINERAL WOOL ROCK MINERAL WOOL
THERMAL ACOUSTIC FIRE
MYTH Internal partitions require thermal insulation TRUTH Thermal insulation is used to stop the transfer of heat between a building ’ s interior and exterior and vice versa . Generally , the ambient temperature is consistent throughout a property , thus no heat transfer takes place , meaning thermal insulation is not required . Therefore , acoustic performance is the primary function of the insulation and thermal is not relevant for drywall partitions . For this reason , we don ’ t declare R-values on acoustic insulation products for internal applications . Using acoustic insulation will ensure exceptional sound reduction and keeps costs low as you ’ re not paying for thermal performance that ’ s not required .
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