Soundproofing Walls and Floors – On the House

Soundproofing Walls and Floors

By on October 8, 2015

And the almighty developers said there would be condos, and apartments and duplexes of every kind providing badly needed homes for the masses. But the developers were remiss in their prophecy for they forgot to require the builders to install sufficiently quiet separations between dwellings. And it came to pass that all of the neighbors in all of the new dwellings could hear each other and there was anger and confusion among the masses and the privacy that was promised by the developers did not come to pass… at least not right away!

When we were younger we took it for granted that if you lived in an apartment or a condo or a townhouse or a duplex – any kind of multi-family dwelling for that matter – that it was normal to share secrets with your neighbor – whether you wanted to or not. What we didn’t discover until later is that sound can be substantially deadened between homes without spending a fortune.

We once built an apartment on the top floor of a seven-story “mini-skyscraper” in San Francisco. We built inside an existing metal-walled structure. The air conditioning system for the entire building was enormous. It was literally as big as a house. And when it ran it was noisy beyond belief. We couldn’t figure out how a home could be built within 40 feet of such an enormously large and noisy machine without having major noise problems.

We met with an acoustical engineer who suggested that we cover the interior surface of the party wall with three layers of 5/8″ wallboard. He also instructed us to use R-30 fiberglass batt insulation in the stud cavities. We were absolutely convinced that the acoustical engineer was completely out of his mind. We could not believe that three layers of wallboard and a layer of R-30 insulation would effectively quiet the roar of the massive air conditioner. It took about nine months to complete the construction, which by the way was magnificent. The owner chose exquisite finishes.

Anyway, much to our surprise the noise outside stayed there once the sound-wall was complete. Now granted, there were no windows or doors in the sound wall. There were only the studs, R-30 fiberglass insulation and the three layers of wallboard on the inside surface. Oh, and the texture and paint!

It was really funny. You could go outside and hear the roar of the equipment and then go inside and the sound would disappear. It was amazing. We couldn’t believe our ears. But we were convinced. First, we were convinced that multiple layers of wallboard and a layer of R-30 insulation could do the job. And even better we discovered that killing noise doesn’t have to cost an arm and a leg. Wallboard is pretty cheap. And so is fiberglass insulation.

In homes where different families live on opposite sides of a common wall it is best for the studs on one side to be separate from the studs on the other side. We think that two separate walls work best. One wall for one side and one wall for the other side. This way when someone pounds on their wall – as many of us do from time to time – the vibration isn’t automatically transferred to the other side. Also, wallboard should not be applied between the common walls. The layer of wallboard can defeat the sound deadening properties of the insulation layers in each of the walls. So remember the configuration; 3 layers of 5/8″ wallboard, a stud wall filled with fiberglass insulation, a space between, another stud wall filled with fiberglass insulation and 3 more layers of 5/8″ wallboard.

We think that the building code ought to be up scaled to include a full separation between multiple dwellings and that the party walls should each have several layers of wallboard within each dwelling. Wall cavities would be filled with as much fiberglass batt insulation as will fit without compression to add more sound deadening quality. No portion of the wall cavities should be without insulation.

You can’t do all of these fancy framing things unless you’re building from scratch, but if you have room you can build a wall inside your place holding it a few inches away from the existing one and adding as many layers of wallboard and/or soundboard as you can afford. Also, you can simply add wallboard to an existing wall. Keep in mind that if the studs in the wall travel all the way to the other side that some sound may come through even with several layers of wallboard.

There are even some types of soundboard that come with fabric or wallpaper applied to one surface. Cool stuff. Screwing soundboard to a wall is a no-brainer, but keep in mind that properly extending the electrical boxes is important.

If you live in a rental and have noisy neighbors and the landlord doesn’t care then consider moving. Your landlord may not want to spend the bucks that it takes to silence the noisemakers, but keep in mind that you may have grounds to cancel your lease if your landlord’s desire to remain profitable is keeping you awake at night.

For more home improvement tips and information search our website or call our listener line any time at 1-800-737-2474! All you need to do is leave your name, telephone number and your question.


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