Calling all acoustical engineers! How to soundproof a window?
December 2, 2010 1:47 PM   Subscribe

To make a DIY Soundproof Window Plug, what material (or combination of materials) should we use? The window is quite large (9' x 5') and the plug should ideally be relatively lightweight and removable. Looking for personal reviews of the different materials under consideration or suggestions for materials our research has missed.

The window is on a walkway in a rental building, so the main problem is voices and privacy. The goal is to greatly reduce sound from going in or out via the windows. There are already heavy duty decorative custom drapes on the window.

The window is 9' wide x 5' high, and the window framing is 6" deep all the way around. The window is single paned glass in 3 sections, the middle is a solid pane of glass and the two outer sections are louvered.

Rental Building = No Chance of Window Replacement.

The window size is awkward because most materials come in linear feet (rolls of 2' x 25') or sheets of 4' x 8' (sound deadening board, acoustic sheetrock, etc..)

The current idea is to cut down three 4'x 8' sheets of polystyrene insulation board to 4'x 5' to at least fit the height of the window (the polystyrene board is a lot like "foam core" you'd use for art projects, but insulation grade) and stagger that over the entire 9' x 5' space. Attached to the insulation board will be sound dampening materials, and then the individual sheets will be upholstered so it looks pretty from the walkway. The upholstery will add stability to the overall construction.

Here are some materials and fabrication ideas:

- The cheapest/easiest/lightest way to go seems to be 1" insulation board covered in a layer of pink fiberglass insulation then upholstered with a tight weave fabric. We're certain the sound dampening qualities on this are minimal. Opinions?

- 4' x 5' insulation board is green glued to 4' x 5' sound deadening fiberboard + layer of fiberglass insulation + upholstery fabric. Is the weight of the sound deadening fiber board worth the sound proofing effect?

- 4' x 5' insulation board green glued to a layer(s?) of mass-loaded vinyl + a layer of insulation or America Mat (acoustical foam padding) or dense felt + covered by upholstery fabric. Can anybody comment on the effectiveness of mass-loaded vinyl (MLV)? Thanks!

- would hanging sound blankets (like they use at rock concerts) in between the custom drape layers be just as (in)effective as the first idea above of using of 4' x 5' insulation board + fiberglass insulation + upholstery fabric?

- Any kind of acoustic sheet rock seems too brittle and heavy to be worth using... are we correct? Or are the soundproofing qualities of acoustic sheet rock so superior to MLV or even regular fiberglass insulation that it is worth the weight and expense?

Other ideas ranged from using egg crate foam mattress padding attached to insulation board or plywood, to stuffing the window with old futon mattresses (gross!).

We do know that leaving air space between the window and the soundproof layer is helpful in blocking the transmission of sound waves, as is avoiding the use of screws, nails, or any framing that might convey sound waves.

How would you tackle soundproofing this flimsy 9' x 5' window?

posted by jbenben to Grab Bag (3 answers total) 4 users marked this as a favorite
Wall to wall carpet remnants tacked to frames might work, you could make three frames out of 2x3 that would be easily movable and fit tight together. maybe put some extra layer of something behind the carpeting, like rigid foam insulation.
posted by mareli at 3:21 PM on December 2, 2010

I'm a big fan of sound deadening board. I made a window plug out of several overlapping layers to block sound transmission from a window in a band practice room, and I've also used it to block sound on a sliding door between rooms.

It's relatively cheap, light weight, available at big box construction supply stores, and you can cut it with a bread knife if you don't have a saw handy. If you're going to be handling it on a regular basis, put duct tape on the edges so it doesn't crumble.

I haven't tried it, but building a panel or panels out of a framework of 2x2s with a layer of sound deadening board on either side and some kind of fibreglas or even cotton batting in between would probably work pretty well for your application.
posted by zombiedance at 4:25 PM on December 2, 2010 [1 favorite]

Similar problem- 8x5' window though which makes it a little easier. How did that work for you?
posted by msalt at 12:24 PM on July 10, 2011

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