Will Holes in a Wall Affect Its Soundproofing?

The short answer is; yes. When it comes to basic soundproofing, any gap, crack or hole (like those left after an electrical re-wire) can significantly reduce the performance of an otherwise soundproof partition.

Sound insulation is used to reduce any sound that can pass through a structure. Sound is carried between two spaces via two different routes; the wall/floor and also indirectly, as it travels through the structure which surrounds it – this is known as ‘flanking’.

Flanking can often take a more complex and less obvious route around structures, like floors or walls which flank objects such as an open window or a partition, doorways, corridors, air ducts etc. This is the main reason why it’s so important to make sure everything is airtight when you’re building an acoustic partition; even the smallest hole or gap can mean a lot of sound escapes through.

To give you an example; a single square hole around 25mm in size can affect the performance of a otherwise soundproof partition by as much as 15db. Sound leaks that are around one-tenth of a percentage point of an overall partition can limit the partition’s effectiveness to about 30db, even if that same partition had been rated at around 55db.

Any noise problem you have should first lead you to the weakest part of the structure you’re looking at. When talking about walls, sound insulation is normally purely related to airborne sound, such as music, television or speech, whereas floors also need to be soundproofed against impact noise such as footsteps or things being moved from one spot to another.

The average sound insulation when protecting against airborne sound, when talking about solid structures, usually depends on mass. So the heavier the material which can be used for transmission the greater it can resist any airborne sound transmission. Which explains why it’s easier to hear what other people are saying or doing when walls are thinner.

The soundproofing in any structure will always perform better if any higher mass layers can be isolated from your existing structure.

If you are experiencing problems with noise pollution from an existing wall partition, you must first inspect your wall and any adjoining areas/abutting walls carefully to check whether sound insulation is at optimum efficiency.

If possible, also examine the area of the wall within the roof space for any problems such as missing bricks; if any are missing, they should be replaced. Also check for cracks, small holes or any unfilled mortar joints, which can then be sealed with cement mortar mix. It’s also wise to check for gaps, cracks or any bad mortar joints behind skirting boards or in spaces between floorboards.