TDS -Soundproofing A Basement Practice Space

We are often asked by residential owners how to reduce noise from basement music practice areas. The common question, “how do we soundproof the basement”? There is really no such thing as soundproofing. Sound can be decrease din wood framed residential construction in the mid-range and high frequencies effectively, but low frequency thumping from kick drums and bass guitars is very difficult to reduce. In band practice rooms, sound levels can be very high (thanks drummers!) which adds to the complexity. Keep your expectations realistic. You will not eliminate all the noise. The goal should be to reduce the noise enough such that it doesn’t drive the upstairs people crazy. That can be done with a little work. The noise reduction methods we will describe area simple solution that will effectively reduce the noise by about half (a-10 dB drop). It is intended to reduce noise from about 100 Hz and higher. Kick drums and bass guitars, without other noise reduction methods, could still be problematic. We have given some other methods of reducing these types sounds later in this discussion. There are also many other construction methods to reduce noise further, but these are more expensive and much more construction intensive.

It’s actually best if your basement ceiling is unfinished (no drywall and open wood joists). This is because finished basement ceilings are rarely insulated and adding acoustic materials in the existing ceiling cavity can be tough. The noise reduction methods we will discuss assumes an unfinished basement ceiling.

Typically, a basement ceiling is made up of lightweight layers. On top of the basement ceiling joists are usually a single layer ¾” tongue and groove plywood and whatever the floor surface of the room above. This could be anything from carpet & pad to tile or wood. This is not much mass to reduce noise, especially at lower frequencies. You also most likely cant rip up the floors and start over, so any noise reduction solutions must be installed easily in the basement. So, what we are going to do is create a ‘lid’ for the basement.

Noise will typically follow the path of least resistance so any gaps in the ceiling construction caused by electrical, plumbing and HVAC systems will allow noise to pass to the upper floors of a house. These gaps should be sealed with non-hardening caulking and/or packed with batt insulation. It really comes down to details. Any opening in the ceiling/floor assembly, no matter the size, will allow noise to pass through. If the ceiling has HVAC ducts between the joists it will drastically reduce the effectiveness of any noise isolation. Ducts transfers noise easily to other parts of the house. It may be worth investigating having these removed and rerouted by a qualified mechanical company.

Don’t let anyone tell you installing absorptive panel sin the basement will fix the problem. While adding certain types of absorption helps listening conditions considerably, it does very little to prevent noise from transferring upstairs. We will talk more about room absorption later.

Isolation Budget:

• 1 lb. per square foot Limp Mass Vinyl $1.00 –$1.25 per square foot
• R-13 batt insulation $0.40 -$0.50 per square foot
• Door seals $35 -$45
• Misc. items (tape, staples, screws etc.)$50

The basement door should be sealed first. Go to the hardware store and buy a heavy-duty weather seal kit that includes a rubber sweep for the floor. The idea is to make the door as air tight as possible. If the door has a hollow core, it may be worthwhile to replace it with a solid core unit. As an alternative, you can also purchase sound rated door seal kits such as those from Zero International.

The basement ceiling will give you the biggest bang for the buck as this has the most exposure to the upper floors. The goal is to place a flexible, air tight as possible barrier between the rehearsal space and the basement ceiling. Assuming you have exposed ceiling joists it’s a two-step process.

1. Install R-13batt insulation in between the ceiling joists. This can be obtained from your local home improvement store. Do the entire ceiling. Note that R-13is only about 3” thick. You don’t need to fill the entire joist cavity. Buy the Kraft face insulation and staple to the bottom of the joists.

2. Staple or screw limp mass vinyl sheet to the bottom of the joists. Where the vinyl sheets have a seam, overlap them slightly and run a strip of duct tape so they are completely sealed. Run the sheets all the way to the walls and a few inches down the walls. Seal the joint at the walls with silicone non-hardening caulking.

NOTE: If you have electrical, plumbing or HVAC devices in the ceiling you should never cover these up. Safety first! Instead, cut an opening in the vinyl (ex: a hole for a light fixture, a rectangle for an HVAC grille)and seal around the fixture with caulking. You can also create an access door for plumbing traps, etc. by cutting a square opening in the vinyl under the area. Then, cut a larger square vinyl cover so it overlaps and use duct tape to seal. The important thing is to allow accessibility to any electrical junction box or fixture while making the vinyl layer as air tight as possible.

If you have an exposed stairwell leading to the basement, consider enclosing it. This could be a complex as building a stud wall and covering with drywall, or as simple as hanging noise damping sheets from the ceiling to the floor. Typically, stairwells are an acoustic weak point (remember the door seals discussed earlier).

Room Absorption

Now that we have talked about noise isolation, we can discuss how the interior of the room sounds. Remember, these are basically two separate issues. The trick here is to only add enough absorptive materials to make the room pleasant to play in. Adding too much will make the room sound dry and lifeless.

Hang absorptive blankets behind the drum sand near the basement stairs. You can also place these in the room corner sand mid points of the walls. About 40-50%of the total wall surface should do. Like most basements, there will probably be shelving, boxes and other items distributed around the room. These can actually help to absorb sound.

Build gobos. Gobos are simply movable absorptive boxes made out of 2x6lumber. The cavity is a sandwich of one layer of 2” fiberglass board, one layer of 1/8”peg board and a second layer of 2” fiberglass board. The whole thing can be wrapped in fabric or simply left unfinished.

Interior Absorption Budget

• 4’ x 8’ Absorptive blankets $1.75 -$2.25 per square foot
• Gobos –2” thick fiberglass board (Owens Corning #705 or equiv.)$1.50 -$1.75 per square foot
• Gobos –2x6lumber, peg board, screws etc. $35-$45

Other Ideas for Bands

• Invest in in-ear monitors or use over the ear noise cancelling headphones. Costs have come way down, and these are indispensable for rehearsal spaces. This allows the back line equipment (guitar, keyboard amplifiers) to operate at much lower volumes. Best scenario is to use DI’s (direct injector boxes)instead of microphones for the guitar and keyboard amps and feed a mixer to distribute the headphone or in-ear mix. If your mixer has the capability, you can setup different monitor mixes for each band member.
• Vocal microphones should face away from the drums.
• Do not place the drums or bass amplifier in the corner of the room. This will increase the noise level. Instead, place them half way down a wall. Use a thick rug under the drums.
• Use just a few microphones for the drum kit. One microphone over the drum kit and possibly one on the kick drum is all that’s usually needed for rehearsals. Less is more!
• Build gobos. Gobos are simply room dividers that have absorptive sides. They should be about 4 feet tall so that you can see over them. Place these around the drum sand in front of any amplifier with a speaker.
• Use drum head and cymbal dampeners. Although these don’t give the same sound, they can reduce basement noise levels considerably. These are available on-line or at your local music store.