I’ve put a lot of effort into making my office and home more soundproof, and I frequently get asked how to soundproof a window by friends and clients. Whether it’s street noises, airborne sound from neighbors or even your kids banging around outside, quieting outside noise transfer can make life more relaxing. It will also improve the quality of sleep, so you feel more rested and able to handle daily stresses.
I was putting together my suggestions on how to decrease sound transfer through windows for friends and clients and decided I’d share it with anyone interested. I hope you find it helpful.
Inspect Your Windows
Most windows in houses are installed after the walls are up, and are whatever the builder chose. They may be double pane, but not necessarily the best STC or OITC rated which bites into the profit margin.
Window Condition Affects Soundproofing
Check to see if your windows are single, double, or triple paned. If the builder or last occupant left any information on the windows, review it for an STC rating. Many windows have information etched in a bottom corner, so you may be able to get information online about your windows.
Make sure they are working properly. Check for cracks and breaks in the seals between window panes. If the window has moisture or fogging between the panes or a cracked pane, they can be repaired.
Feel around the window perimeter, sliding seals, and even the wall next to the window and casing. If you feel heat or cold, or even a breeze, you need to do some maintenance. Place your fingertips on the window and vibrate them, if the window moves with them, you have some work to do. Ensure the latch and closures work and seal correctly too.
Check the outside caulking and seals between panes and around the frames. Any gap or hole is a highway for sound. One easy way to check if the window seals properly is a lit candle.
Place it on or near the sill on a windy day with the window closed. If the flame flutters, there’s air coming through, which means sound can too. Move the lit candle to the sides of the window and see if it reacts to a draft.
Note: Don’t put a flame near curtains or other flammable material.
DIY Window Soundproofing Methods
1. Seal Any Air Gaps Around the Windows with Acoustic Caulk
Air leaks are the easiest way for sound to travel into or out of a structure, and one of the easiest fixes. Replacing weatherstripping and cracked or crumbling caulking will reduce sound transfer.
Begin with the outside, and then do the inside. Make sure the caulking is suitable for the material your frames are made of and use acoustic caulk if you can. The following steps will work well on the inside of your windows.
Remove the casing trim carefully, so it doesn’t split. If there is a narrow gap between the drywall and the frame, seal it with acoustic caulking or my favorite, Green Glue noise proofing sealant. I prefer Green Glue as it forms an airtight seal, is paintable and deadens noise.
If the gaps are wide, insert strips of mass loaded vinyl (MLV) or neoprene rubber to seal the space. They eliminate vibration and noise transfer. Don’t use spray foam as it doesn’t have the mass to stop sound waves.
If the gap is 1/2″ or so, stuff in fiberglass or stone wool insulation. I also like to use Backer Rod; it’s a closed cell filler rope that insulates too. Seal the stuffed crevasse with acoustic caulk.
Weatherstripping for windows is available in different thicknesses, widths, and lengths. Measure the dimensions for what you need, and purchase the correct product – rubber, foam, silicone, or fibrous.
Most have a self-adhesive side for ease of installation. Measure exactly, so there are no gaps, peel, and stick where appropriate for the type of window.
Here are some products I have found work well:
Green Glue Noiseproofing Sealant
A sealant in a tube like caulking that fills gaps and cracks that sound can penetrate. It forms a vibrational separation that won’t shrink. It stays pliable when it cures and is paintable.
A flexible self-adhesive neoprene rubber strip used to fill narrow cracks or gaps. It’s available in various thicknesses, widths, lengths.
A closed-cell foam rope used to fill wider gaps in masonry and frame construction. It won’t expand and is impervious to moisture. The rope is available in different lengths and diameters.
I find the soundproof neoprene foam rubber tape works well in some windows and D-type gap blocker in other windows. It also depends on the type of window.
2. Hang Sound Absorbing Curtains for Windows
After ensuring the window is properly insulated and sealed against noise, an inexpensive addition is curtains. I don’t mean lightweight shears but thick heavy velour panels that will absorb sound. Soundproofing or blackout curtains trap frequency waves in their folds and also keep UV rays out during the day.
Recycled polyester fiber is spun and woven to make the fabric used in many acoustic curtains. The fabric absorbs and decreases reflection, softening the sound as it passes through the material.
It improves listening enjoyment by controlling reverberation and echo. It’s available in multiple colors and is often treated to be fire resistant. A good article to read for more information is Sound Absorbing Fabrics.
The heavier the fabric weight, the better it will be at absorbing sound; 32-ounce velour is a very good weight. Multi-layered curtains are great too. Many blackout or thermal insulated curtains have a reflective vinyl layer covered by velour panels, adding to the mass and acoustic properties.
Heavy curtains are often STC rated between 25 and 33, which is similar to single and inexpensive double and triple glazed models common in many subdivisions. Considering that uninsulated interior walls are rated at 33 on the STC scale, a heavy curtain can only improve the sound quality in your home or office.
- Control reverberation and echo
- Available in multiple colors
- Sound and UV blocking
- Fire resistant
- Don’t block all sound
- Heavy and dense fabric
NICETOWN has a blackout curtain with a thermal liner that blocks light and UV, plus dampens sound movement. It’s available in a selection of sizes and colors, and won’t break the bank.
3. Install Thick Material Soundproof Blinds
In addition to the curtains, or as an alternative, install blinds. As with curtains, the thicker the material, or the more layers, the more effective they will be at controlling some sound. Honeycomb blinds or thick roman blinds work well.
However, the blinds should be wide enough to cover the trim work to be effective. Remember, the outside-inside sound movement comes through the window and the molded trim work. The more light that can get through the blinds means more sound will too.
Honeycomb blinds have an R-value between 3.5 and 7, which means they’ll save on energy costs. It also means they are effective at reducing sound transfer. The blinds are available as a single layer or a double honeycomb cell shade.
The honeycomb design is the best blind for reducing sound transfer. The blinds can be installed so the rise from the bottom of the window, or drop from the top. Depending on the material they are made from, they may or may not permit some light through when closed.
Roman blinds offer a more stylish blind option and will deaden some sound too. They are available in thicker and denser fabrics, which improves their absorption properties.
Roman blinds are available in a variety of colors, and fabric thicknesses. The heavy fabric folds help trap sound waves and control noise transfer, so the heavier, the better.
Roller blinds are often a vinyl material. They can be multi-layered for insulating against UV and like any light blocking blind will also work to reflect or absorb sound.
Blinds can be rolled up from the bottom which will block out some sound but still allow light through above. If you’re working at a desk, it can reduce sound intrusion without cutting out all the sunlight.
- Reduce some sound transfer
- Insulate against cold and heat
- Darken a room for an improved sleep
- Easy to install
- Don’t block much noise
- More effective when covering trim and window
Calyx Interiors carries a cordless honeycomb shade that insulates against thermal and sound transfer. It’s reasonably priced and available in different colors and sizes.
4. Install Soundproof Window Blankets
Window blankets or barriers are another way to block out light and thus sound. They can be attached to window openings with hooks and grommets, clips, loops, or Velcro. Some DIYers attach them to pulleys and make roller type blanket blinds. They dampen sound and block out light.
Mover’s blankets are thick quilted panels that are an inexpensive option but limited to a few size dimensions. Some acoustic products have an MLV (mass loaded vinyl) sheet sandwiched between fabric coated fiberglass layers for added insulating properties. Many industrial blankets used to reduce machinery noise can be adapted to cover windows and prevent sound transfer too.
For more detailed information on using moving blankets to soundproof windows, please see our article Soundproof Blankets for Windows.
A 72”x80” mover’s blanket weighs in at 7.7-pounds, the 48”x96” Singer Safety Double Faced Quilted Fiberglass Panel is a hefty 53.2-pounds, and a 48”x96” acoustically designed blanket tips in at 48-pounds.
The heavier and denser the blanket, the better it will control sound movement. The blankets are also wider so will more easily cover the window and frame, increasing their effectiveness at blocking sound.
When selecting a blanket to block or absorb sound through the window, thick is better. Some acoustic blankets have a reflective or MLV layer, making them more effective than simple quilted cloth covered insulating material.
A 1/2″ blanket offers some control. However, a 1” blanket has an STC of 27, a 2” is rated 32, and 4” pushes to 34. They perform better at mid to high-frequency control, so the throbbing of a subwoofer will still resonate through, but not as loudly.
- Absorbs and blocks sound
- Don’t have to be permanent
- Can be cut to fit
- Limited color options
- Block most light
- Difficult to access window
Here are a couple of recommendations:
Singer Safety Double Faced Quilted Fiberglass Panel
The fiberglass quilted panel fluffs out to 2-inches thick and blocks light and sound. It also creates a thermal barrier over windows. The 4’x8’ panel can be cut to different sizes, but the edges need to be taped or sewn to prevent the fiberglass from escaping.
Quilted moving blankets are fabric with polyester fiberfill. The 72”x80” panels are a lighter, thinner (1/2”), and less expensive option for blocking light and absorbing noise through windows. Some come with grommets for hanging, and some don’t.
5. Install Acoustical Shutters
Shutters aren’t just for show. Interior and exterior shutters can be installed to decrease sound, light, and UV intrusion. Louvered shutters look nice but don’t block as well as solid panel shutters. Some shutters claim to block 100% of sound and reducing noise transfer by 50dB; they also have a steep price tag.
For the best soundproofing, and best looking, interior shutters you might want to look at ShutEye Acoustical Shutters.
If you don’t want to mortgage the house, you can make interior shutters using MDF panels lined with 1/2″ self-adhesive cork and some hinges. The MDF has more mass than plywood, and the cork is a natural sound absorber.
Shutters will block most mid to high frequencies, but a low frequency like that teen’s subwoofers and modified exhaust even vibrates through walls.
Roll-down shutters are made of metal or polycarbonate material. They can be motorized or manually operated. The motorized models can be operated from inside with a remote or switch too.
The roll-down shutters are designed to protect windows and doors from hurricane force winds, so work well to block sound movement too.
- Reduce sound and light penetration
- Strong and durable
- Increase privacy
- Protect from storms and theft
- Motorized also require battery back-up
6. Install External Storm Windows
Adding a storm window to your windows will decrease the sound penetration and is less expensive than installing new windows. The storm wind deaden sound transmission ow creates a dead air space between itself and the existing window, which helps to further. The wider the gap between panes, the more effective they are.
Some storm windows have sliding panels and screens so you can open them when you want, which also means they are less effective at blocking sound. Exterior storm panels usually have a frame and can be secured permanently with screws or seasonally with butterfly tabs. Adding adhesive weatherstripping will improve the seal and block more sound movement.
- Deadens sound transmission
- Look like windows
- Allow light through – won’t darken rooms
- Easy to install
- Most don’t open, so decreased access to fresh air
- Can frost or fog up
7. Use Noise Blocking Window Film
If you don’t want to add another pane of glass or plastic but still want to dampen the sound coming through the windows, there is a noise blocking film that can help. Plastic thermal films that attach to window openings with a reusable clinging attachment instead of adhesive strips can be reused.
The plastic film has acoustic properties as well as thermal uses on windows. It is available in many different patterns and colors to suit any creative whim.
The common window films attach to the window opening or framework, not to the glass. The film will cover the window and any cracks or gaps in the opening, making for a quieter experience inside.
The air trapped between the plastic sheet and the window pane helps deaden sound, and the plastic sheet blocks sound vibration. The plastic is also more flexible than glass, so it reacts more softly to inside sound reflection than glass.
- Reduces noise penetration
- Works on any window
- Blocks UV rays
- Can’t open windows
- Can be punctured easily
8. Install Clear Sound Barrier or Window Insert
Acoustic inserts for the inside of windows work across the frequency spectrum for sound abatement in your home or office. The higher the thermal properties, the better at controlling sound the insert will be.
Some even claim to decrease sound intrusion by up to 80% and an STC of 48. However, it’s more likely to be rated between an STC of 26 and 30. The heavier the material is, how tightly it fits into or over the opening, and the amount of vibration and airflow is blocked by the seals impact the performance.
An insert helps reduce noise and sound vibration. It will work better on mid to high frequencies, so voices but not that subwoofer. The air space between the window glass and the added pane also helps to block sound movement.
However, if you have blinds, you may have to move or replace them as they won’t fit or work in the window opening. If the added pane doesn’t fit tight, the sound will squeeze through any cracks or gaps.
Soundproofing Window Seal Kit
If you live in an apartment or house, there are soundproofing window kits available. Some kits have self-adhesive magnetic strips and others double-sided tape. The adhesive strip goes around the perimeter of the window opening – inside the trim.
You need to have a pane of glass or clear acrylic cut to the exact dimensions. Depending on the product, either stick it to the double-sided tape or use the matching magnetic strips to attach it in place.
The insert with the double-sided tape is a more permanent option since it is difficult to remove. The kit with the magnetic strips allows for the insert to be removed when desired for cleaning or fresh air, and then replaced to block noise.
Both products provide an acoustic seal that improves sound control. Some magnetic strip kits include a frame that is available in several colors and even customized for different shapes.
Transparent Mass Loaded Vinyl Barrier
Mass loaded vinyl in transparent format is a good way to improve block noise and voices. It is available in 1/2-pound, 1-pound, and 2-pound weight per square foot, with an STC rating of 20, 26, and 33 respectively. The dense mass blocks mid and high frequency sound better than low range sounds but does provide improvement across the ranges.
The MLV can be stretched across the opening and secured with double-sided tape, magnetic tape, or a DIY customized frame. The vinyl sheeting comes in widths from 24” to 54” and lengths up to 100-feet.
Other dimensions are available too, and some even come with Velcro strips sewn around the perimeter. The MLV improves sound quality and provides a thermal barrier for better temperature control.
Make DIY Soundproof Window Inserts
You can make a clear, sound barrier insert. Make a wooden frame that can seal tight in the existing interior opening. Hardwood or MDF is better than softwood or plywood.
Notch or cut a groove for a glass or plastic pane to fit into. Trim the edge with weatherstripping to block sound movement, and slide or secure it into the window opening. You do need to attach a handle or knob with which to remove the insert.
The DIY insert can be shaped to fit any window and is removable so you can open the outer window or for cleaning. It creates an air pocket between the two sets of panes which deadens noise transfer and improves sound quality.
I’ve used chair-molding to make the frame, so when it’s installed, it looks like the window is trimmed out normally.
Sound Barrier or Window Insert:
- Reduces noise transmission
- Look like windows
- Allow light through – doesn’t darken rooms
- It installs and removes easily
- Doesn’t open, so no fresh air
- Adhesives may damage paint or trim
- May not look professional
9. DIY Removable Soundproof Window Plug
Making a window insert that will absorb and deaden noise is another way to block outdoor-indoor sound transmission, and also block light. The size of the window may influence the construction and materials you choose.
Making a plug for a 2’x3’ window isn’t much different from doing one for a 4’x4’ or 72” patio-window. However, they will cost more and weigh significantly more.
The main parts of the plug are fairly easy to get at your local building store. They’ll even cut to your measurements if you ask.
Mass is one of the key ingredients required, plus some fiberglass, stone wool, or cotton insulation to absorb sound, Green Glue sealant to seal all joints, some MLV, and weatherstripping to seal around the plug. I don’t recommend rigid foam as it doesn’t absorb sound well.
Before you begin, consider how you are going to lift the plug into place and secure it so it can’t fall on someone. Plugs can be heavy depending on window size.
You’ll also want to consider where it may be stored when not I use. Additionally, the depth of the window opening is important. If it is 6-inches deep, leave half the space for deadening airspace – so 4”s is 2”s and 12” is 6”s.
I’ve included one way to build a removable plug, but there are a lot of plans available online too if you want other building ideas.
Accurately measure the inside dimensions of the window cavity. Some windows have a raised lip or other bumps that need to be considered. Also, look at the trim around the window and determine how the plug can seal inside or around the window. Remember to leave airspace between the window and plug.
Cut the lumber that will form the frame that fits inside the window opening. 3/4″ dimension lumber works as well as 2”x4” and is lighter. For larger openings add horizontal or vertical cross pieces every 26 to 24-inches.
Test fit several times. You can use angle brackets to square and tie pieces together.
Cut the material that will form the room side face of the plug frame. I recommend MDF over plywood or drywall. It has greater mass and blocks more sound; the thicker the material, the better too. If you double layers use Green Glue between the layers to stop the vibrational transfer of sound.
Run a bead of Green Glue around the edge of the frame and secure it to the face. Attach handles and test fit – adjust if necessary.
Cut the fluffy or rigid fiberglass or stone wool insulation to fit into the frame, and compression fit it into place.
Cover the back of the plug (the side that is closest to the window), so the insulation can’t fall out. You can staple acoustic fabric or a mover’s blanket over it.
Cover it with MDF or plywood will add to the mass and weight. My choice is attaching a sheet of MLV since it won’t react with moisture trapped between the plug and the window like wood will.
Attach weatherstripping to the perimeter, install, and enjoy the quiet. Remember to secure it so it can’t fall out.
- Inexpensive sound blocking solution
- Blocks out light for Bedrooms or Media rooms
- Only use when needed
- Removable, so the window is usable
- Heavy to move
- Where to store when not in use
- Detracts from the aesthetics of the building
- A temporary solution
10 Replace The Windows With Double-Pane Windows
Replacing old windows with new, modern framed ones will offer an immediate improvement since the new window should fit and seal better in the frame and wall cavity. Upgrading the window to double pane over a similar window or even a single pane may not have much improvement in the STC of the glass.
A 1/8” single pane is STC rated at 27, and a standard double pane at 26. You may notice an improvement due to the fit, not necessarily the glass.
Upgrading the window is a big expense and should involve products that will significantly improve the STC or OITC value. Double or triple panes are a good bet if they are laminated, insulated, dissimilar or soundproofed panes. An upgrade should be something better than you have presently, so don’t settle for what you have.
Some triple pane windows are the same thickness overall to a double pane, which means they probably have similar STC values. Remember, the more air space between panes of the same thickness, the better.
Using 2 panes with PVB film laminated between two glass sheets and a 1/2” air space between panes can run an STC of 37. It looks like a standard double pane window but blocks much more sound.
Insulated windows will offer a similar improvement in sound control to the laminated glass. Triple laminated or insulated panes with more airspace between panes should perform a couple of points better.
Soundproof windows are best, but the cost may put them out of reach. If you live on the flight path of a major airport, you may want to consider it though.
- Improves sound control
- Reduce heating and cooling costs
- Can still see out and use window
- May not need other sound blocking methods
- May not block disruptive low frequencies
11. Install Soundproof Windows
Soundproof windows will block between 90 and 95% of noise moving through the window. If your walls only block 60 to 65% of noise, the expensive soundproof windows may not help.
Additionally, the low-frequency sound is more difficult to stop than mid and high range sounds. If you decide to spend the money, look for windows with an STC rating of 50 to 55.
Soundproof glass and frames are specifically designed for different frequency ranges, so each is custom made. They often include laminated panes and airspaces of different thicknesses. The windows block not only sound but also UV rays, helping to prevent fading of furniture and flooring.
The cost of soundproof windows depends on the size of the opening and where you live, plus the frequencies you want to stop. Living on a flight path may encourage you to buy specialized treatments, and it may do the job.
However, you may want to do some price comparison first. The cost of a 3’x5’ laminated triple pane window with an STC of 41 may seem steep at $1,000 until you get a quote for a comparable soundproof window at closer to $10,000; not counting installation!
- 90-95% effective
- A better-looking solution
- Blocks UV rays
- Not a DIY option
12. Block The Window Entirely
Blocking the window completely is an extreme noise reduction response. If you’ve blocked all avenues for noise to travel through the window and attempted several of the other options, then blocking the window may seem right.
However, it is a decision that should involve testing the sound transmission through your walls and your windows. Blocking the window only to realize the noise is pounding through the walls won’t help.
The easiest way is to make a plug similar to that suggested in this article and secure it permanently. Due to the buildup of moisture between the existing window and the plug, use rock wool and MLV (mass loaded vinyl) as they handle moisture better and resist mold growth.
You may also want to paint the inside of the panes and any wood with a quality mildew resistant paint to prevent wood rood and mold growth. Use corrugated vinyl to cover the inside of the panes to improve the aesthetics looking in from outside.
Alternatively, you may want to delete the window completely, frame the opening, insulate, vapor barrier, and finish to match the interior and exterior finishes. If you don’t need it, remove it.
Removing a window may require a building permit and reconfigure of the HVAC system due to the change in air exchange within the room – something to consider before getting out the sledgehammer.
Additional Non-Standard Methods
There are other, less expensive or permanent options to living with airborne noise intrusion.
Use a White Noise Machine
Many people in apartments or noisy areas opt for machines that produce white noise. They mask outdoor sound, so it seems less obtrusive.
There are machines that work with speakers, earphones, or Bluetooth. They may take some getting used to, and may not block low frequencies, but compared to the cost of other options, they help.
Use a Big Fan
Fans have long been used to mask intrusive noises. They create a steady whir that hides other sounds and makes sleep easier. White noise fans are available in different sizes.
Some are rechargeable, or battery operated, and you can even get an App with the fan noise for travel purposes.
Sound Cancelling Headphones
Headphones that cancel disruptive sounds and permit a good night sleep are a worthy investment if you live in a noisy area. Whether you use them to block almost all sound or use them to provide quiet noise masking music so you can get a night of undisturbed sleep, they can be an effective alternative to moving.
Why Soundproof Your Windows?
Outside noise can interfere with your peace and quiet and sleep. Ever been watching a good show or been sound asleep and the neighborhood teen roars in with his music louder than his thrush mufflers? You miss the dialogue, or your sleep is ended, and any chance of relaxing shot.
Sound travels through the air, so anything that blocks, absorbs, or reflects sound from outside will have energy-saving benefits for your home. Windows and doors are the biggest holes in a house and can let in many sounds. Ensuring they are properly insulated and sealed is one way to decrease noise intrusion.
When you soundproof windows you decrease air movement in and out of the opening. Depending on how you block the sound, you may reduce the UV rays that enter, which helps save on air-conditioning costs. UV rays can also fade furniture and artwork, and even bleach out hardwood floors and carpets.
Soundproofing windows can decrease outside noise transfer by up to 95%, saving you money on energy costs, plus protect your furniture and home from harmful UV exposure. You’ll sleep better, and be able to have quiet and even private conversations in your home. There are many benefits to soundproofing your windows.
The Basics of Windows Soundproofing
Windows are the best place to start when soundproofing a home or office. Sound absorption and reduction are the two basic principles to consider when decreasing sound transmission through windows.
Reducing the amount of sound entering through windows is the first step. The windows are barriers to sound waves entering or exiting your home. Window manufacturers make the glass thicker to add mass, increase the airspace between the panes to decrease transfer, and laminate the glass with a film of plastic to further control noise.
Increasing the Sound Transmission Class (STC) of windows is one way to improve their ability to block noise. The higher the STC rating usually means it’s more expensive too.
Sound that does enter your home or office bounces or reverberates around the room, creating more disruption. Absorbing the sound that makes it through the window will further decreases outside noise interference.
Exposed brick or stone walls and wood floors reflect sound waves and add to the chatter of a room. To decrease the reverberations, add carpet or rugs with under padding, put up acoustic panels or wall hangings, and use thick window curtains that absorb sound. Additionally, padded furniture and plants will also absorb unwanted noise.
Sound Transmission Class (STC) for Windows
The STC rating of windows depends on the thickness of the glass, the thickness of the airspace between panes, and the use of plastic laminates. The construction and materials used in the frame of the window are also factors to consider.
The rating indicates how well the combined parts of a window block sound transmission. The larger the value, the better it is at decreasing sound movement.
Walls, windows, doors, floors, and ceiling (plus the roof) all combine to block noise movement. An STC of 40 is the minimum for privacy, and the building codes push for a rating of 50 to 55.
Windows are unable to stop 100% of noise movement, but some do a better job than others. If the sound outside the window is 70 dB and on the inside, it is 30 dB, then the window has an STC rating of 40 depending on the frequencies blocked.
It is interesting to note that single, double, and triple pane windows can all have the same STC value too. A single pane is often thicker glass, while the individual panes in a double or triple are thinner.
Triple and double pane windows often fit in the same frame track, so are the same overall thickness. Which means the airspace between panes in the triple is less than that in a double.
Always check the STC rating of your windows before you purchase them. You don’t want to pay more for a triple than a double with the same STC rating.
Here are average STC values for common windows:
|Window Type||Low STC||High STC||Common STC|
|Single pane 1/8”||21||28||27|
|Single pane 1/4″||30||32||31|
|Single pane 3/8”||33||35||34|
|Single pane 1/2″||35||37||36|
|Triple pane insulated||39||41||39|
Note: The common STC value represents what builders get from box stores. If you want higher STC rated windows, expect to pay more. Laminated means two panes of the same thickness with a polyvinyl butyral (PVB) layer between. Dissimilar panes have two panes of different thickness which disrupt different frequencies and improve sound control.
Outdoor-Indoor Transmission Class
The Outdoor-Indoor Transmission Class (OITC) is a similar rating to the STC. However, it measures transmission loss (TL) beginning at 80 Hz instead of 125 Hz. The lower frequency represents noises we hear from heavy trucks, trains, planes, and lawn mowers so is of more value when rating windows. That neighborhood teen’s bass music and thrush exhaust again.
Most windows will have a lower OITC rating since it includes lower frequency noises than the STC rating, which makes it a better indicator for noise reduction for your windows. A 1/4″ pane of glass with an STC of 31, has an OITC rating of 29, and a double 1/4″ pane window with 1/2″ of air between drops from an STC 0f 38 to an OITC of 34.
The same applies to soundproof windows with double laminated panes rated at an STC of 42; they drop to 33 on the OITC scale.
Remember, both OITC and STC rates equal the number of decibels of sound the window blocks, so the greater value is better. If your home or office is near rail lines, airports, or truck routes, you want a higher OITC rated window since it measures from a lower frequency.
I hope you found this article useful. There’s a lot of information to take in, and some solutions are aimed at the homeowner instead of the renter. The first step should be to check the weatherstripping and insulation around the window.
Installing or improving it may make enough of a difference that other options aren’t necessary. If you know someone who may benefit from this article, pass it along, and remember, your feedback is appreciated.