People are becoming more aware of and interested in the benefits of putting acoustic insulation in their homes, but there is considerable confusion about it. Any insulation material will offer both thermal and acoustic protection. Generally, the thermal effectiveness of an insulation material increases at a rate similar to its thickness. The acoustic effectiveness is more dependent on the density of the product. Most of the more usual blanket type insulation products have similar acoustic properties and values to each other. Some manufacturers change the colour and price and call one ‘acoustic’ and the other ‘thermal’ even though the two may be almost identical in composition and do an almost identical job both thermally and acoustically.
There are some specialist products manufactured specifically for acoustic performance that come in a variety of different materials, primarily compressed polyester or glass wool, supplied as a sheet. They are 3 –5 times the price of standard new house insulation and are usually seen in specific situations in commercial work. They are rarely used in residential buildings due to the cost and sometimes the difficulty of installing them to their full potential in a residential design.
For most residential situations, effective acoustic dampening can be achieved at minimal cost by using a standard thermal/acoustic new home insulation product in the walls or ceiling and installing multiple layers of plasterboard as the lining. It is important to avoid breaching the plasterboard, for example, with back-to-back switches and power points.
While insulation and multiple plasterboard linings will dampen air noise like speech, stereos and TVs, it will be less effective against direct transference noise such as a chair scraping over the floor above or direct thumping on a wall. For this type of suppression, it is important to provide a break in the direct fastening of the plasterboard to the frames, joists or ceiling battens. This can be achieved by using one of a number of propriety solutions that usually involve holding the plasterboard off the wall frames and ceiling joists with brackets.
Be aware that any break in an acoustic wall has the potential to seriously reduce its effectiveness. For example, a standard hollow core door in an acoustic wall will render the acoustic performance of the wall virtually useless as the sound will simply carry through the door. If an acoustic wall must have an opening such as a door, it is vital that it have the appropriate acoustic rating and seals.