Custom Audio Designs Ltd

DIY Domestic floor Soundproofing

Part E | Sound Insulation Regulation | Robust Details | Building Regulations

DIY Domestic floor SoundproofingDIY Domestic floor SoundproofingDIY Domestic floor SoundproofingDIY Domestic floor SoundproofingDIY Domestic floor Soundproofing

How to Soundproof Domestic Floors

Even in new build flats, that are built using the correct materials and methods, loud noise from music or shouting etc. may still be heard.

To tackle the issue you really need to identify the type of noise - impact - i.e. footfall or, - airborne - i.e. talking, and the source of the noise, (floor, ceiling, wall or a combination).

1. Standard Floating Floor

(airborne and impact noise reduction)

This is a floor that is 'isolated' from the existing structure by a 'resilient' layer.

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For this method the floorboards are lifted and either High Performance Acoustic Quilt such as 2FT80-B Quilt or 100mm Acoustic Mineral Wool is placed between the joists. The floorboards are then screwed into the joists to prevent movement when walked on. (Insulation between the joists and a floating floor is required by the Building Regulations for all new build and conversion projects).

Next, a resilient layer, such as our Isobase R50 is placed over the base floor and a new Tongue and Grooved (T&G) floor is placed on top with all the T&G joints glued and sealed together. 22mm Tongue and Grooved (T&G) wood flooring is a good overlay board, but even better results can be obtained from using Cement Impregnated Particle Board.

NB. It is imperative that the resilient layer does not touch either the walls or the skirting. When the resilient layer is in place, the small perimeter gap should be sealed with flexible sealant.

Installing the system above will increase the floor height by approximately 30mm therefore all doors will have to be adjusted accordingly at the thresholds.

A 15mm floating floor option is available if height is an issue.

2. Higher Performance Floating Floor

(airborne and impact noise reduction)

For a higher performance floating floor simply repeat the steps in (1) but glue two layers of T50 or acoustic membrane, (laid in opposite directions) to the floating floor before replacing the underlay and carpet.

Alternative options

(when it is not practical to fit a floating floor system):

1. T50 acoustic membrane

(airborne and impact noise reduction)

Firstly, seal any gaps between the floorboards with Acoustic Sealant to make the base floor airtight. Then cover with two layers of 3mm thick T50 or VL-65 acoustic membrane laid in opposite directions, and glued using Spray Adhesive.

This is the absolute minimum you can do to defect the transmission of airborne sound through a floor.

2. Quietfloor Premium+

(airborne and impact noise reduction)

A significant improvement to option (1) can be achieved with the addition of Quietfloor Premium+ slabs on top of the two layers of T50 or VL-65 acoustic membrane before replacing the carpet. Please note, it is essential that the sheets are laid in a staggered, brick type pattern, and that they are butted tightly together and up to the perimeters of the room. Due to the 15mm thickness its best to first run a 9mm thick timber batten, the same width as the grippers (about 25-30mm wide), around the room perimeter. The grippers can then be nailed into this raised batten.

Caution: if your sub-floor is not level you will need to bond the sheets down to prevent any subsequent lifting due to bowed flooring. In older properties even if you have levelled out a floor using chipboard it's still possible that the small irregularities are dealt with but the overall floor may rise and fall in line with the old joists. Small sheet material may want to 'lift' in certain areas if it is not bonded down.

Squeaky Floorboards

Many people find squeaking floorboards extremely irritating and they are best dealt with before adding any soundproofing materials to a floor. This noise is usually caused by boards rubbing against boards or the joists they are fixed to. The most common problem we find is due to poor nailing when undersized nails have been used or the nails are spaced too far apart. The best way to sort this out is to screw, rather than nail, the boards down securely.

We have also found that defective materials are another cause of this. Warped or twisted joists, bowed subfloors/wood sheathing can all cause the materials to rub against each other. Wherever floor materials move against each other squeaking will result. Sometimes all that is needed is to add some mineral oil around the squeak but this tends to wear off after time as the problem can re-occur. This however can be useful for tongue and grooved flooring that has weak or broken T&G links.


The results you will get when doing this will depend on workmanship, materials used, methods used but improvements can sometimes be limited by 'flanking noise'. This phenomenon is where a percentage of the noise may not only be transmitted directly through the wall but also via adjacent walls touching the separating floor and this can vary from one project to another. It often depends on the existing structure.

For example if the floor is a concrete floor slabs built correctly into the wall then the floor acts like an added resistance to the sound trying to 'flank' through the wall but if the floor slab is not built in but butted to the wall and the wall leaf is continuous between houses there will be excessive flanking transmission and you would have to treat not only floor or ceiling but also the walls as well.

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Another typical example of bad conversions is where the end joists run parallel to the party wall. Insulation may have even been installed in the past but the gap between the end joist and wall was left. This may have been because someone thought it wouldn't make much difference but it will ! In siutations like this, without taking things apart to investigate, there may be hidden problems which will again limit the improvements that would otherwise be achieved.

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All information contained in these details is given in good faith but without warranty.
Custom Audio Designs reserves the right to alter the specifications of any product without notice.
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