Good Thinking

Spring-loaded screw could be a cheaper form of soundproofing

Spring-loaded screw could be a...
The Sound Screw – coming soon to a wall near you?
The Sound Screw – coming soon to a wall near you?
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The Sound Screw – coming soon to a wall near you?
The Sound Screw – coming soon to a wall near you?

Nobody likes hearing their neighbors' music, TV shows or loud conversations. Soundproof wall materials, however, can be quite thick and expensive. Swedish scientists have developed a thinner, less costly alternative, in the form of a spring-loaded sound-damping screw.

Known as the Revolutionary Sound Absorbing Screw (or the Sound Screw for short), the device was created by a team at Malmö University, led by senior lecturer Håkan Wernersson. It consists of a threaded section at the bottom, a coil spring in the middle, and a section with a flat head at the top.

The screw is inserted into a hole drilled through a drywall panel and into the underlying wooden stud. It is then turned until its threaded section is all the way into the woodj, and its head is sitting flush against the outside surface of the drywall. The spring forms of a gap of a few millimeters between the stud and the drywall's underside.

When sound waves from an adjacent dwelling subsequently travel through the wooden stud and into a wall's Sound Screws, the compliant springs in the screws limit the transmission of the vibrations into the drywall. As a result, people in the room hear less of the noise.

In lab tests involving traditional drywall panels, it is claimed that Sound Screws reduced through-the-wall sound levels by 9 decibels, which worked out to about half the perceived sound when traditional screws were used. The technology also performed well when trialled on the ceiling of a hair salon, where the existing standard screws were simply replaced with Sound Screws.

Wernersson tells us that the screws are already available in Sweden (via spinoff company Akoustos), and that his team is interested in licensing the technology to a commercial partner in North America.

"The initial price is quite high for a screw, but cheap for a sound insulation system," he says. "The cost will decrease with volume."

Sources: Malmö University, Akoustos

The cheaper alternative would be that people would have a little more (respect) and (consideration) for their neighbors, but this is a great idea! Truly outside the box thinking!
Chuck Mulder
The idea is good....and applicable to timber walls...
The sound screw is designed for timber walls, not floors. The word joist/s implies it can be applied to floors. I'd suggest the words joist/s are substituted with stud/s , timber wall framing etc, as joist/s are used for the structural members for ceiling and floors. Eg; floor joists, ceiling joists. My TAFE teacher would say, wood is in the trees & timber is the structural material we use as carpenters. So maybe substitute wooden & wood with timber. See timber framing components An alternative design screw pitch suitable for steel studs would also be good, as we use timber & steel studs in Australia
The description given here of how this works is incomplete/misleading. There is obviously a second threaded portion of the device on the (sliding) portion of the very top of the device (as opposed to the countersunk portion at top of the screw-proper). I am guessing (but no explanation on the maker's site either - that the very top threaded portion engages with the plasterboard itself, supporting it but then allowing the plasterboard (and threaded top portion of the device) to move along the axis of the screw compressing the spring. Quite how that helps reduce sound transfer is a mystery as it would seem to me that the more rigid (and dense) the medium, the less likely it is to transmit sound at right angles to the board - it's just acting like a loudspeaker only more than it would with normal, rigid screws... Perhaps someone who actually knows what they are talking about can clarify?

And @ Chuck... I can't see why they couldn't be used on plasterboard ceilings...?
This is an expensive solution looking for a problem that has already been solved. Expensive both in materials and labour.
Its like inventing a square wheel!
The existing solution, is foamed Polyurethane. Just a series of squirts onto a board, or the supports, and the board, can then be pressed against any surface and held in place until the foam sets. The PU foam is a natural sound damper, and the airgaps behind the boards, also provide some thermal and sound insulation. This is far cheaper, quicker and needs less skill from the operators, reduces fixings to the minimum, and also the surface finishing, with no multiple screw indentations to fill and cover.
Sounds to me like a labour intensive product. Since labour is more costly that material I suspect that using a sound/fire break rock wool is still a more beneficial alternative.
If you really want quiet walls simply offset and zigzag your studs by a couple of inches. Then drywall in one room is only attached the "zigged" studs while the opposing room's drywall is attached to the "zagged" studs. This completely isolates the two rooms so no sound is transmitted by vibration except at the footer and header, which are 6 inches wide to accommodate the offset studs. You do lose a bit of square area in the room as your hollow space between rooms is larger, but the side benefit is you have more room for insulation.
Obviously, there are lots of ways to soundproof. We use something like this to hold down large fuel injectors in a Main Engine in case it's exposed to excess pressure. It lifts and then reseats. No, you don't need threads in the top section. The rock is held by the screw head on one side and the top of the spring on the other. It won't be expensive or difficult to install. All of the other methods have their expense and problems too. Good to see a new entry in the soundproofing field.
What happens when the joints between gypsum board are taped, spackled and painted? Is there enough movement if someone leans on wall the seam will crack? Extra thick or double board will have close to the same effectiveness.
Keith Thompson
What about taping over and concealing the fastener? Too expensive, product over engineered. Sound proof foam cheaper faster and works better.