Soundproofing a House
A walking tour….. using soundproofing products.
You swing out briskly walking trying to keep up with Robby, the clean-cut guy you met touring his apartment soundproofing job.
“Hey! Wait up, Robby!” You puff. “You’re going too fast!”
He slows a bit and says: “We’ll have to hurry to get it all in, especially if you want to look at all the stuff I’m going to show you. But anyway, here we are!” Together you enter a average looking two story house on a quiet street.
Folks on the street idly eye you both as Robby’s key opens the door.
You enter a wide hallway with doors leading off in different directions.
Robby speaks: “You’ll notice the doors in the hallway do not line up across from each other. That’s so sound doesn’t transfer across and through opposite open doors. This is one of the little known principles of soundproofing, called “staggering”.
“At the end of the hall is the basement. we can visit that at any time you like to see what special methods are needed for a good soundproofing job. One of these doors (a ‘double-door’, this side opening in, the other opening out), leads to the garage, where I’ll show you how we soundproofed it for band practice.
You notice that while the floor is hardwood, the wallpaper covered the “Super Soundproofing mat” on the walls and ceiling contribute to the richness of the sound of your footsteps.
“At least 25% of a room should have some absorbent material to reduce reverberation. This can be furniture, carpet, or whatever. If the balance is right the sound is rather pleasant. Lets go up the stairs”. You follow obediently.
At the top of the stairs, another hallway is presented. Again, doors open off to the sides.
Robby says: “Here we have carpet on the floor of the hallway to absorb sound because this is mostly a bedroom area. Not much need be done for soundproofing purposes except for the bedroom floors as this is already a quiet area”.
“That door over there leads to a small apartment over the garage. And that one is a “safe room“.
He pushes open one of the doors. “In this bedroom here, we must have something on the floor for soundproofing as this room is right over the living room. Here we have made the floor a major part of our soundproofing effort. Take these x-ray glasses and have a look.”
He hands you that appears to be a small video camera.
“See, on the LCD screen you can see right through the structure of whatever you point it at. Adjust the “focus” to see further or less into the floor”.
“We call them our “Super Soundproofing Looking Glasses”. he says proudly.
With a little practice you can look at the underlying structure of the flooring through the camera.
Clearly you can see the floor joists, the sub flooring and their overlays.
“What’s so special about this?” You ask.
“Well, not much except that we’ve taken the trouble to put “Soundboard” up between the rafters from below and selected special recycled carpet padding for the overlay. The most important item is the use of the “Super Soundproofing Floor Mat”. It’s what they call a loaded vinyl and weighs about one pound per square foot. That makes it an excellent soundproofing material”
“Could you use something else?”
“Sure, some inexpensive things like acoustical ceiling panels could be used instead of the Soundboard, but there’s not much of a price differential. The recycled carpet padding costs even less than regular padding! The SSP flooring replaces lead sheeting and is fairly expensive but there is no inexpensive substitute”.
“My ceiling has lots of noise because the flooring above it has squeaks!”
“Can you make repairs from above? Usually renailing it will quiet it down”.
“No” You tell him.
“Tear down your ceiling and woodscrew triangular wood strips to the flooring above and to the joists. It helps if you use a copious amount of “Liquid Nails” adhesive. This will keep the flooring above from moving about and stop the squeaking. You’ll probably want to add some Soundboard or Homosote in between the rafters before putting your ceiling back in. They should have taped the tops of the joists before putting down the subfloor!”
“Good Idea!” You wave the camera about. “Say, I’m beginning to really like this device!” You notice as you adjust the “focus” that you can see for quite a distance right into the house next door!
“Well, take a look with it down into the walls of the rooms below, to see how we staggered the studding. This provides vibration isolation from one wall to the other, prevent sound transfer from room to room”.
“Yes, yes! I can see it clearly!”
“You can do this with tape to existing wall studding, too!”
“The some of the other things we could have done to improve on the soundproofing of these walls is to add another layer of drywall to them. We would have specified more 5/8” “fire code” drywall. This would be done by placing them on “hangers”: resilient channels or sound clips used as vibration isolators. They also space the drywall out somewhat from the existing wall so there is an increased air space. We did use this type of “double drywall” on the walls facing the street. This adds to the soundproofing effectiveness. What you probably can’t see is that we placed “flooring” (MLV <Mass Loaded Vinyl>)in between the drywall panels and took the time to carefully caulk around the drywall so as to eliminate any spaces sound can enter or come out.
We staggered our electrical boxes, one sire to the other, placing them at least two feet apart where possible. We also caulked around them thoroughly”.
“I see you used blown in insulation”.
“Yes, more for convenience. If we had used “R-14” we would have used the compacted kind for added soundproofing over the regular kind, sometimes referred to as C-703 or C-705. We could have stapled asphalt roll roofing to the studding but for the odor, but the insulation guys come with a truck and do the walls and attic all at the same time. Remember, this was new construction. Even though the soundproofing effectiveness of the roofing material is greater than the insulation and is cheaper, we did it for convenience”. Mass Loaded Vinyl or lead is superior to all of the above, but is more costly.
You look around the bedroom. “What about those windows?”
“We used double paned glass and vinyl frames. These are a bit more expensive, but not as expensive as true acoustical windows. Over the life of the house, acoustical windows are well worth it. We put shutters on the inside and if we have trouble with a noisy neighbor, a party or something and really need to get to sleep, we just stuff a layer of 2” thick Super Soundproofing Mat in the window. It’s thick enough to stand in place by friction. If a more permanent installation is needed, we can visit the windows section to see how it’s done”. In a place where we must have light along with substantial sound reduction, we use a interior windows custom made to fit inside the frame. Acoustical Drapes/Curtains are an alternative, too.
You say: “Let’s get on with the tour!”
“Bear in mind that these types of improvements increase the value of a home drastically, especially when you’re the one living here!” He says.
“Flip that switch on the camera and you convert it to an Infared Scanner! Now you can see temperature differences were heat is leaking from cracks and seals. Such air leaks means sounds can migrate through, because sound is a lot like water, it will find the path of least resistance.”
Want a copy of the EPA’s out-of-print popular book on Soundproofing? “QUIETING: A Practical Guide to Noise Control”. (Over a hundred 8.5″X11″pages). Read this and you won’t need a consultant! Info on homes, walls, materials, STC ratings and much more! Many illustrations. Available for just $15 PP to cover copying costs and postage. You can download it too!