How to Create a Soundproof Loft Conversion

A loft conversion is a great way to extend your living space, but no one wants a music room which causes arguments with the neighbours or a cinema room which disturbs those sleeping below.

Creating a room which has the potential to be a noise nuisance to neighbours can be especially relevant to flats, terraced and semi-detached homes, but of course all homes may also struggle with the effects of noise coming in from the outside. In busy urban areas such as London, where even residential neighbourhoods can be extremely noisy, a minimal level of soundproofing is desirable, whilst significant soundproofing might actually be essential.

It’s well known that sound travels so creating a loft conversion which offers sound proofing involves both blocking sound so that it cannot travel (into or out of the space) and absorbing sound, so that any ongoing effects are lessened. When it comes to a loft conversion, it’s important to include design, construction methods and materials which both block and absorb sound, not just to minimise noise nuisance, but also to allow privacy.

Making the sound barrier

The possibilities for soundproofing your loft conversion will largely depend on the proposed use of the room: for a yoga room, home office or library it’s preferable not to have household or neighbouring sounds disturbing the calm, so blocking the transfer of sound into the room is essential. Likewise,, for a loft-based games room, music studio or home cinema, it’s not at all desirable to allow sound to travel down or across to neighbouring properties.

In all cases, because the loft is the top floor of the home where there are usually sleeping areas below, it’s also particularly important to prevent noise from footfall and movement from creating a nuisance to the floor below, so adequate soundproofing to floors is usually desirable however you intend to use the room.

Similarly, the walls will need to be adequately soundproofed against the passage of sound to and from neighbouring properties and external areas, whilst the actual roof, ceiling and windows will need to offer protection from any extremely loud sounds coming from outside or overhead, such as seagulls and ground or air traffic.

Sound solutions

As such, there are plenty of areas where soundproofing layers can be added to a loft conversion, to help reduce noise impact. Soundproofing on the basis of absorbing or blocking sound, including reverberating sound, is usually achieved by using specialist materials which can be included as part of the general loft conversion build:

Walls and ceilings

• Any cavity walls should be filled with cavity wall insulation, which provides thermal as well as a degree of noise insulation.
• Stud walls should then be installed over existing walls, with an appropriate gap of at least an inch between the two, to act as an air buffer which both absorbs and blocks sound. Using high density acoustic plasterboard instead of standard plasterboard enhances soundproofing, as it acts as an effective sound blocker.
• The addition of a high density acoustic membrane will also help to prevent sound transfer between rooms via the walls and ceiling, whilst mineral wool is another material which can also be installed in layers between timbers on supporting floors and across ceilings, with layers being variable to provide the depth of protection relevant to the use of the room.
• Stud walls can also be fitted with resilient bands, which isolate plasterboard from direct contact with the studwork, minimising reverberation and the transfer of sound throughout the frame.
• Foam tiles can also be added to walls and ceilings for additional soundproofing in rooms such as music studios, where enhanced sound absorption is essential.
• Fitting sockets is a small but important detail to maximise sound proofing efforts to walls: sockets should not be fitted opposite the wall behind, but away, to minimise the transfer of sound.

Windows

Doors and windows commonly allow sound to leach in and out, so suitably glazed windows are a must. Double glazing, with its air gap barrier to help reduce sound, is desirable but triple glazing is additionally useful, particularly where there are likely to be issues of external noise or where using the new room’s likely to generate noise beyond a general domestic volume, such as music room or home cinema.

For internal doors triple glazing, generally seen on commercial premises, is too heavy for internal doors in a residential loft conversion, whilst relevant fire regulations might dictate that another type of door required. However, adding an acoustic seal and quiet-close on suitable domestic doors can help to eliminate sounds travelling into and out of the room.

Floors

When soundproofing a loft conversion it’s extremely important to pay attention to the loft floor as it needs to do everything: stop sound escaping and becoming a nuisance to the floors below, plus preventing sound travelling upwards into the room. Achieving this can be effectively done for little extra cost by using:

• Layers of quality carpet underlay as a quickly installed and practical solution. In the case of carpet mite allergies, floor boarding laminates which include enhanced soundproofing layers are available.
• Acoustic mineral wool as this material offers triple the density of standard loft insulation and can provide a highly effective sound absorbing layer which also doubles as thermal insulation.
• Just as acoustic mineral wool can be used like regular loft insulation, within the gaps of joists, acoustic quilting may also be used before laying the new floor (or relaying the old one).
• For general footfall issues, laying additional rugs can help to absorb footfall sounds.

Pipes

An unexpected way in which sound travels is through noisy plumbing and pipe systems. As soon as the conversion designs are available, check that any new plumbing includes acoustic pipe insulation and that any stand-alone plumbing, such as a macerating toilet, is appropriately insulated for acoustics. It’s worth checking these details with your loft professionals at the design stage as it’s usually cheaper for materials can be upgraded as required at this stage than refitted afterwards.

Reducing noise and cutting cost

Of course, effective sound proofing doesn’t have to happen in isolation of other insulation needs, such as thermal insulation, and happily there are many products, such as acoustic mineral wool, which can support both thermal and sound insulation.

However, it’s worth being aware that although some acoustic products also offer some thermal protection, thermal insulators such as polystyrene or Kingspan are effective for thermal insulation only, not for sound. As it makes financial sense to install insulation which is both noise and thermal efficient, double-check the details of the materials being used to gain the maximum benefits for keeping sound and heat at comfortable levels.

Getting the measure of soundproof materials

To help check the efficiency of materials, attention should be paid to the product detail or overview, which measures the sound proofing properties of materials as a Sound Transmission Class (STC) rating. Low STC rated materials are less effective, whilst a high STC rating indicates a material which is more effective for soundproofing.

All of the materials you would expect to be part of the loft conversion can be available with a STC rating – windows, wall materials, carpets and underlay, so speak to your loft designer and project manager to ensure that the materials being used offer the maximum effectiveness to suit the room’s construction and proposed use.

Finally, to fully answer the question ‘can I have a soundproof loft conversion’ it’s worth knowing that where loft conversions are concerned, it may be truer to ask ‘must I …?’ as there are building regulations are in place to protect neighbours from noise nuisance when it comes to converting living areas. Always check with the planning office of loft professional to see whether Part E ‘Resistance to the Passage of Sound’ will be relevant to your build, so you can provide the soundproofing required to enable everyone to enjoy your use of the new loft conversion.