Idea for outside window molding.

[stryped1]

I am contemplating putting 1/2 inch insulation sheet on top of tar paper wr ap to increase r value and decrease the noise of my ac outside my bedroom.

My window has and integrated channel to hide the vinyl siding. However, whe n I held a piece of the insulation to it it completely filled it. I could p ossible "smash" the siding into it but have not tried.

I got to thinking, would it look stupid on a skinny and tall window such as this (32x72) to dress it up by using some of that white pvc (or whatever i t is) brick mold around the window? (I think it is rated for interior and e xterior use but not sure). My idea would be to put a small, skinny furring strip on top of the foam, then the pvc brick mold on top of that. The furri ng strip would be skinnier than the mold so as to create a channel to hide the edge of the vinyl siding. This may not work as it may make the molding sit out way in front of the window, I don't know. I could put the furring s trip or strips directly on the nailing flange of the window of a thickness just enough to clear the half inch foam and whatever thickness the siding i s.

I would think they would make a j channel such as this but no one locally h as one or acts like they know of such a thing.

[Tekkie®]

[e-mail] posted for all of us...

And I know how to reply in-line

Bad idea. Use noise blanket for AC.

Another bad idea.

Don't think, another bad idea.

You think wrong.

[nestork]

Every company that makes or installs PVC windows or doors in your town will have 1/8 inch thick PVC sheet, typically in a 20 inch width. They use it to make PVC "returns" on the window they install. Often, the walls of the buildings they install their windows into are thicker than the windows themselves, and so they need something to make up that difference between the window frame thickness and the wall thickness.

If your intention is to reduce the noise from your air conditioner, then insulation isn't going to help much. When a sound wave hits a wall (for example) the sound wave DOES NOT travel through the wall. Instead, the wall moves slightly as a result of the sound wave and that motion recreates a second sound wave on the other side of the wall. It's that recreated wave you hear, not the original.

It's this simple as dirt method of sound propogation through walls that's the basis of the MASS LAW of Acoustics. The mass law says that for every doubling of the weight of the wall (per square foot) OR for every doubling of the frequency of the sound wave hitting the wall, the amplitude of the recreated sound wave on the other side of the wall is reduced by 6 decibels, or to 1/4 of it's former amplitude.

That's because the more massive the wall, the less it moves in response to the sound wave hitting it, and that means the amplitude of the recreated sound wave is also reduced. Also, the more massive the wall, the less able it is to can change it's direction of motion quickly. So, the higher the frequency of the sound wave hitting the wall, the less capable the wall is of reproducing that sound wave. In the ultimate instance, the inertia of the wall would prevent the wall from responding to a high frequency sound wave at all, and the result would be silence on the opposite side of the wall.

So, to stop the noise from your air conditioner, a smarter gameplan would be to install heavy shutters on that window that could be closed. You want to avoid having air paths through the shutters that the sound could travel through, so your shutters would either be solid and block the light, or you could have the shutters made out of 1/2 inch thick glass, perhaps.

Also, have curtains made for that window from the thickest and heaviest drapery you can find. Almost certainly MOST of the sound you hear is coming through the closed glass window, and so that's where you should concentrate your efforts at reducing the noise. Put as much mass between you and the air conditioner as you can, and that will stop more noise than your insulation idea.

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