Will your new home be as quiet as you want? 

I have a dog problem. Actually, it’s a multiple dog problem. This is despite my doggy friends’ assurance that almost all dog problems are, in fact, dog owner problems. In other words, change your behaviour and your dog’s behaviour will also change – hopefully for the better. Let’s leave that for the moment.

My doggy problem consists of two dogs who love to bark – at pretty much anything that catches their fancy. The upside to this is exceptional home security; our only fear is stone deaf intruders.

The downside is the noise. It’s loud, intrusive and wildly unpredictable. Not the best sound track for someone working from home. Worse, we have frequent doggy visitors – courtesy of my daughter’s dog walking business – which only adds to the cacophony.

So I decided to follow my friends’ canine advice and change my behaviour. I decided to convert the integral garage into a sound-proofed doggy den.

It seemed easiest to start with the bedroom above. The fitted carpet needed replacing, as did the 60-year-old floorboards beneath. I’d already planned to insulate the underfloor space to staunch the heat loss to the insulation-free garage below. So, under the 150mm of standard mineral wool, went 50mm of sound insulation slab, courtesy of a special offer at a local builders’ merchant.

Next came a new 22mm chipboard floor, ready for a new fitted carpet, for which my supplier offered a standard rubberised underlay. Or, on hearing my interest in sound proofing, a specialised acoustic version. That sounded ideal.

Until I heard the price. Almost four times the standard version. What were they doing? Rebuilding the floor? Insulating it with crushed diamonds?

In fact, it was more like the former, and a demonstration of one of the main principles of sound proofing, known as ‘decoupling’. Here, the floor is separated from the supporting joists – typically by a metal flange which straddles the timbers. Dense material – usually thick plasterboard – is laid between the flanges, while sound insulation is fitted between the joists. A strip of insulation is also fitted around the perimeter of the room.

This method dampens sound in two of the most effective ways : by adding mass and by creating an air gap. Ceilings and walls can also be soundproofed in the same way.

It’s a standard means of retrofitting existing properties where a quiet space is needed, such as an office, music room or teenager’s bedroom. But what about a new build? How can you be sure your new home will be as quiet as you wish?

The Building Regulations do have sound insulation requirements. Part E, which operates in England and Wales, requires a minimum sound reduction of 40 decibels (dB) in internal walls and floors. This means that loud speech can be heard but not clearly understood.

It’s relatively easily achieved with blockwork walls and concrete floors; timber frames will need internal insulation and thicker plasterboard.

One easy way to judge if that’s enough for you is to visit a recently built standard developer’s house, or, better still, quiz anyone who’s lived in one for a few months.

Factors that are likely to demand higher levels of sound insulation in your new home are: an open-plan layout, high ceilings, hard flooring and large expanses of glass – all of which can amplify noise and ease its passage.

Another source of noise or noise transmission is a mechanical ventilation with heat recovery (MVHR) system. Ironically, it’s often specified to create a sealed house to minimise intrusive exterior sounds, such as heavy traffic or flight paths. To keep systems as quiet as possible, aim for rigid ducting, with short runs and as few corners as possible.

Pipework, too, can produce noise. The NHBC require internal soil pipes to be wrapped in at least 25mm-thick sound insulation and, in habitable spaces, be boxed in by 25mm-thick plasterboard. But insulating other pipes where they aren’t running through already insulated wall or floor spaces will also reduce noise and energy bills.

Creaking floors as new floor joists dry out and adjust to loads are also a common noise complaint. Consider using I-joists – joists made from timber flanges linked by steel struts or engineered wood. They’re as strong as solid timber but much more dimensionally stable.

But to guarantee a quiet home it’s important to design in sound insulation at the earliest stages and, ideally, choose a construction method that makes it easier. One such is insulated concrete formwork (ICF) where the house is a solid shell of reinforced concrete. Another is straw bale construction where the thickness of the lime-rendered straw bales creates a unique internal atmosphere.

If you prefer more conventional forms of construction consider building to the ultra-energy-efficient Passivhaus standard. Using high levels of insulation and airtightness and triple glazing it can deliver up to 65dB of sound reduction, six times the Building Regulations requirement. St Gobain take that a stage further with their Multi-Comfort standard.

But if all that seems a little OTT, and expensive, there is a more demanding version of the Building Regulations based on the requirements for party walls and floors. Known as Robust Details, they are a list of specifications which are pre-approved to meet Building Regulations.

Applying them to internal walls and floors, which should involve only a marginal increase in the amount of insulation and plasterboard, may be all you need. And if you still require specific quiet rooms have a look at British Gypsum’s Sound Solutions at their Rooms Made For You website.

One thing, however, is key to acoustic success, whatever method you choose, and that’s attention to detail. Like water, sound will slip through the smallest gap – a scrap of insulation missing from an internal wall, holes in floors left unfilled by second fix tradespeople. Good sound insulation is really about sound building.

November 2018