Understanding Noise to help Sound Proof a Party wall
We all enjoy a bit of peace and quiet, and any unwanted noise in your home can be a real pain. Noise that comes from the road, railways, or air traffic, noisy neighbours or industrial processing can make life intolerable.
It may be difficult if not impossible to shut out unwanted noise completely, however it is possible to reduce noise levels in almost any house or flat so that they are much less irritating.
Here are a few tips on how you can soundproof your party wall and reduce the noise around your home and create your own fortress of solitude.
Remove skirting and fill any gaps, replace floorboards and seal with flexible sealant, re-point any old or poor mortar joints, add mass to the wall in the loft by plastering, clad partition walls to prevent internal noise transferring from room to room, add a separate lining to the party wall and fill the gap with soundproofing insulation.
All of these techniques will help reduce the amount of noise that is transferred. Which ones will work best will depend on several factors. I have put together more details in the post below, take a look and find out which ones will help you to reduce any problem noises.
Why is my house noisey?
There are several reasons that you hear lots of noise from next door or outside your house. Understanding how sound is transferred is key to enabling you to reduce it and give yourself some peace and quiet.
When a Sound is made, if you shout, for example, the air in front of you is made to vibrate, this creates pressure waves. The louder the sound the bigger the vibrations and the larger the pressure waves.
For example, the noise made by igniting TNT or dynamite is so loud, the resulting pressure wave will knock down solid walls or entire buildings.
The pressure waves and vibrations of a sound can be transferred to various other things, like the materials used to build your home, these will then want to resonate, making the noise ‘echo’ through the building.
Which materials reduce noise in a house?
The materials that are used to make up your home react differently to sound waves. Some will absorb and reduce noise and some will resonate and echo the sounds.
Soft materials reduce noise because they act as insulators, carpets, curtains, and cushions for example. Hard surfaces like brick, ceramic tiles, and plastered walls reflect sound making them worse. Thin materials will resonate and increase noise whereas thicker materials absorb more noise.
Thicker materials provide better sound insulation than thin materials as they require more energy to move and vibrate.
Things that contribute to make noise in a house
In modern buildings, the lightweight housing materials, which provide excellent thermal efficiency, are not as dense as materials used in the construction of older, traditionally built houses which tend to provide better soundproofing qualities.
Thin materials such as sheetrock or drywall plasterboard provide very little resistance to sound energy and can amplify sounds. Gaps between the floorboards and under skirtings and doors allow sound to penetrate into other spaces, as do loose-fitting doors and windows which can rattle and bang.
All of these factors can contribute to the problem of penetrating noise around your home.
The most efficient way to reduce the transfer of noise between rooms is to provide an airtight barrier that has sufficient mass to prevent vibration, this acts as a break between the cavities and helps change the way the sound vibration moves through your property.
Soundproofing Partition Walls
Normally being polite and considerate as a neighbor ought to rule out most of the problems associated with noise from an adjoining property, in practice neighbors aren’t always so considerate and noise can easily penetrate a shared wall between properties, making life difficult.
Here are some things you can do to reduce the transfer of noise between properties
Filling gaps Sealing gaps in the party and partition walls will reduce airborne noise, remove skirtings and floorboards close to the party wall, repoint poor mortar joints and fill any gaps around joists that are built into the masonry, refit the skirting and floorboards, seal gaps with flexible mastic. You can also repoint and plaster the loft walls to add mass.
Basically, you need to prevent the free movement of air between the two properties. When replacing the skirting and floorboards, make sure all gaps are filled with dense material and use a flexible mastic.
Correcting any damaged mortar and adding new layers of plaster in the loft space can also help to reduce the transfer of noise. Read our guide on how to plaster for more in-depth details
This adds mass to the party wall, reducing the vibration which can then resonate inside the loft which is often an open space with no soft surfaces.
You may consider adding some cladding to partition walls, this will reduce any noise that passes from room to room.
To do this you can line both sides of existing stud partitions with additional sheetrock or drywall plasterboard ½” (12.5mm) thick.
Make sure that any gaps or joints are fully taped and sealed, then you can reattach the trims and baseboards or skirting boards.
If you intend to construct a new stud partition, use two layers of drywall plasterboard on both sides and include some soundproofing insulation between the drywall.
Soundproofing Party walls
The noise transferred from one property to another via the Party wall is often the most annoying as it is unpredictable and random, if you don’t have a good relationship with your neighbours this can become a problem.
Therefore being able to reduce the transfer of noise by improving your party walls ability to absorb sound is a good way to stay friends
Improve the sound-proofing of party walls by constructing an independent, insulated liner, next to the party wall. This is fixed to the floor and ceiling but not the party wall, leave a gap and fill this with mineral-fiber insulation, use 2 layers of drywall plasterboard to clad the liner.
Constructing an independent, detached, and insulated lining next to the party wall will greatly improve the soundproofing between your property and next door,
The effectiveness of a lining will depend on the construction of the party wall, for example, if you have a fireplace, any electrical sockets, pipes or plumbing fittings, and the location of windows and doors.
How to construct the lining
A soundproofing wall lining is built in a similar way to a standard stud partition, it is fixed to the floor, ceiling, and walls at either side, but not to the party wall itself.
There needs to be a gap between the lining and the party wall, which is filled with glass-fiber or mineral-fiber blanket insulation, you can use more expensive sound-absorbing foam tiles however these are not as easy to work with and can be expensive.
The lining is then clad using two layers of drywall plasterboard. Any screws can be covered with some mastic to help reduce the vibrations transferred.
If you own an older house, you may need to remove or modify ceiling moldings to allow you to construct the lining
And it is worth noting that adding false or independent lining will reduce the room size but not by much.
Setting out the stud wall
Make sure you work safely and switch off the electricity supply at the main panel or consumer unit, then check using a current detector that the sockets and lights are dead.
You can then remove and replace any electrical fittings attached to the party wall with junction boxes, this allows you to extend the cables and relocate the fittings on the new lining.
Next, carefully remove the trims and skirting. They don’t always come away in one piece but I find using a wide, flat-bladed tool like this multi tool/scraper helps to avoid damaging them so they can be reused.
Mark a line on the ceiling 4” (100mm) away from the party wall. Then using a plumb line or digital level make a corresponding mark on the floor.
I recommend that you use a laser level like this one from the Bosch Professional range and don’t measure from the foot of the wall as it may not be plumb and this will put your soleplate in the wrong place.
With the stud marked out, you can cut and fix the 3” x2” (75mm x 50mm) sole plate to the floor, this can offer some issues depending on the orientation of the ceiling joists.
If the ceiling joists are parallel to the party wall, it is a good idea to fix additional noggins between them, this will provide secure fixing points for the lining head plate.
Erecting the lining
Screw the head plate in position again using a piece of 3” x 2” (75mm x 50mm) softwood construction grade timber.
Align the front edges with the line you marked on the ceiling and floor. This should give you a 1” (25mm) gap between the inside edge and the party wall,
To improve the soundproofing of the liner you can include a 3” (75mm) wide strip of 2mm or 3mm thick rubber between the timber and the floor and ceiling to act as a dampener.
You can now fix the vertical studs between the sole and header plate, space them out at 2ft (600mm) intervals.
Take a look at our guide to basic wood working joints for more details on how to fix and join studs
Check the width of the insulation you intend to use and adjust the gaps between studs to suit.
As you fix the stud in place mark the centerline of each one on the floor and ceiling, this will make it easier to line up and attach the drywall plasterboard later on.
Once you have installed the vertical studs, Hang the insulation from floor-to-ceiling between the studs, using 4” (100mm) thick insulation,
I use some coated garden wire fixed at regular spacings with hooks fitted to the inside of the studs to help hold the insulation in place, then tucking the edges behind the framework.
Add noggins between the studs where required, to provide fixing points for shelving or electrical mounting boxes.
Double-check that the power is still switched off, then run short lengths of cable from junction boxes fitted earlier across the gap to the new locations for the power sockets.
Once all the noggins and fixings are complete, the liner needs to be covered with 2 layers of ½” (12.5mm) Drywall plasterboard.
Fix the first layer of drywall with screws spaced at 6″ (150mm) then fill and tape all the joints and seal around the outer edges with a good quality mastic sealant, it’s a good idea to apply some mastic to the heads of the drywall screws as well to prevent andy transfer of vibration
Then fix the second layer of tapered-edge boards over the first. The joints should be staggered to avoid flexing and cracking and fixings should be used at regular 6” (150mm) spacings.
With both layers of drywall installed, double-check for any gaps and then fill and tape the joints between the plasterboard sheets exactly as you would for a normal stud-partition wall.
Read our guide to finishing plasterboard for more details and tips
Replace the trims and skirting board. Fix any electrical sockets and connect the wiring.
Use some mastic sealant around the edges of flush-mounted electrical mounting boxes, and fill any final gaps in the baseboards or skirtings to prevent any air movement from the now enclosed cavity between the liner and the party wall.
The new liner can be decorated as any other wall, but consideration to types of materials to use can improve the soundproofing further, thick wall paper, for example, will add another layer of vibration absorbing materials, the choice is yours.
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This article was written by: Richard Quinton – The DIY Help Desk Owner, Engineer & technical specialist.
Richard is one of the key partners in The DIY Help Desk team. He is a qualified Engineer, writer, and publisher, educated to Master’s level. He is a keen advocate of DIY and home improvements.
Richard enjoys helping others to learn new skills and reach their goals and believes that passing his knowledge and experience on through his writing is an effective way to positively impact the lifestyles and well-being of others on a larger scale.
