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The installers view…Soundproofing semi detached house from noisy neighbours

This particular case study looks at the option of soundproofing a semi detached house against noisy neighbours where a client is suffering from specific noises such as; kids running around next door, TV noise, conversation, coughing, plug sockets and light switches and doors banging. Our client like many that contact us everyday can even make out words from next door and recognise songs and TV programs through their party wall. Our objective is to eradicate these noises and also give our client some privacy in their own home.

In this noisy neighbours blog we will consider the floors, ceilings and walls to be treated when soundproofing semi detached

party wall


If you are hearing plug sockets, light switches, running around, banging, thumping and can make out words or TV programs, it is highly likely your floor joists are running into the party wall. This means vibration is being transmitted through floor joists, and sound energy is building up under your floor between the subfloor and the floor boards. In some case’s when you disconnect the floor joists “you can no longer hear the neighbours front door slam” Quietco are called in to investigate many soundproofing DIY attempts or where a builder has attempted to soundproof the alcoves of a party wall. It is always the floors are that have been overlooked, floors are one of the most important parts of any soundproofing project. On this particular project in Gloucestershire, it was really disappointing to find out that a well-known popular soundproofing company from London had done nothing to the floor. Even worse, immediately under the floor boards the Quietco team could get their arm through to next door and tap on the neighbour’s floor.


The London company did not treat the flanking walls, floor or ceilings or loft, only the chimney stacks and alcoves. When soundproofing semi detached properties with suspended wooden floors that have the joists running into the party walls, it is quite common for us to find that there are bricks missing where the joists enter the party wall. Theses gaps are allowing the sound from next door to come straight through into the clients lounge dinner.

party wall
hole in party wall

For most semi detached properties, it is a far more effective soundproofing technique to disconnect the floor joists from the noisy neighbours wall. This means the vibration from next door will no longer transmit through your joists. @quietco we have our own unique way of disconnecting the floor joists, isolating the suspended floor joists from the noisy neighbours wall then offering our clients a floating floor further isolating the floor from the structure. Please see TPSE and TPSP our floating floor range.

Disconnecting the floor joists is best suited for clients with semi-detached homes and  extremely noisy neighbours or those clients with impact noise problems. Quietco manage the whole project including building applications and inspections from the local building control.

soundproofing a home

Chimney stacks

A frequently asked question with this age of property is “Do my chimney stacks need to be treated as part of any soundproofing investment” the answer is YES we would always recommend soundproofing the chimney stack on the party wall. However; have you ever thought of having the chimney stacks removed if you do not use them? It is more effective to run a complete soundproofing system across the entire party wall compared to going around the flanking chimney stack.  Check out our video for the latest advice.


Soundproofing semi detached houses will always involved soundproofing the lounge or dining room ceiling. The sound insulation commonly used is acoustic mineral wool and various acoustic barrier matting together with adding mass to the living room side. Treating this flanking area will not only prevent noise from next door coming over any soundproofing investment, it will also give you privacy and reduce your noise going next door. The ceiling should be treated as part of any living room noisy neighbours soundproofing investment.

Window walls

Soundproofing window walls are always missed but treating the window wall really makes a successful soundproofing investment, “Are you saying the window wall has to be treated too?” Simply put your ear on the window wall, the wall perpendicular to the neighbours party wall. Looking at the window wall the reveal connected to the party wall in particular. See if you hear your noisy neighbours on this wall section? It is highly likely you do, in which case we need to soundproof this flanking area as part of any party wall soundproofing investment. The space loss for window walls soundproofing is normally 3cm see out TPS30W.

Party wall

Quietco has 5 different soundproofing wall systems suitable for soundproofing semi detached homes. As well as cost, space loss is a major factor for some clients and can limit the level of noise reduction achieved. Each wall system tackles different frequencies of noise. The price ranges from £350/m² to over £700/m².

So what was the soundproofing result….

On this particular project, the noisy neighbours allowed an independent acoustic company to test the sound insulation of the property. A UKAS accredited engineer from a well-known UK consultancy company carried out the sound insulations test of the semi-detached property. This means the equipment was set up on both the noisy neighbours side and our client side of the separating wall and they carried sound insulation testing in accordance with procedures following British Standards and Annex B of Approved Document Part E.

The decibel rating of the wall after the London soundproofing company left the job was 38dB down stairs and 40dB upstairs. (Required sound insulation is 43 dB(DnT’w + Ctr) )…..What does this mean: the customer could hear everything and follow conversation of the neighbours in her lounge and dining room, she could make out words and was also woken up by doors banging.

What was the result after TPS70W was installed to the party wall?

Quietco achieved a 60dB upstairs and 63dB downstairs…..What does this mean: We completed the installation in November and returned in January after the painting and decorating was completed to sign off the project. When we asked our client: “What did you hear from next door over the Christmas period?” the client said: “I did not hear anything really….I heard a door slam….I think, though that may have come from outside… and I was sat in the silence at the time”

She kindly wrote us an email a few months later….

“I cannot praise the Quietco Team enough. From the initial consultation through to the end result meticulous attention was paid to all elements of the work.  Following on from the first consultation further detailed discussions were required to make absolutely sure that the work specification would meet my desired outcome, and deliver the peace and quiet which I was seeking. No detail was too small or too much trouble. As a result, the job of soundproofing the whole of my semi-detached party wall, putting in new floating floors and soundproofing the ceilings and flanking walls was completed on time and to a very high standard. During the actual work every effort was made to keep the disruption to a minimum, and every evening surfaces were hoovered and wiped down. The individuals in the team were a pleasure to have working on the job – totally professional. I wouldn’t hesitate to recommend Quietco, whatever the size of job required.”

In summary

Soundproofing semi detached houses room is not just a case of installing a soundproof wall system to the party wall. All the flanking areas of the room such as the floor, chimney stacks, ceiling, window wall and other walls perpendicular to the party wall may need to be soundproofed as part of the investment. (See our case study on TV noise from nextdoor) Although hundreds of our clients are happy with only the party wall soundproofed, we will always design a solution outlining the flanking areas. Please give us a call, or contact us to arrange a call.

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