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Author Topic: Success! DIY secondary glazing story  (Read 7348 times)


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Success! DIY secondary glazing story
« on: September 28, 2017, 08:21:41 AM »

Over the last few weeks I've been reading as much as I can here about soundproofing our townhouse. It is an attractive 3-story 2000 sq ft home on a busy road right on the waterfront.

But my home office and the main bedroom - the two rooms I need quiet for - are on the second floor just 30 feet away from 12,000 cars and trucks each day. And we're also near the flight path to our airport, where aircraft reach only 2,000 ft on their departure/arrival.

However, I knew when we bought this place 2 months ago that nothing was impossible, and so I set to work to get some peace and quiet.

The first step was to order double glazing for both second-floor rooms. I did that partway through my research, and I know now it will make a little difference - but not as much as secondary glazing.

So while I waited for the install early in October, I decided to go ahead and do some DIY secondary glazing, because from the comments on this forum and elsewhere I wasn't entirely sure that double glazing would give the final best result.

So this afternoon I fitted the following to my office window of 4.6ft x 5.5ft:

- Two 6mm / 1/2" acrylic sheets fixed with magnetic tape to the interior outside edge of the window frame, giving an air gap of 4" from the existing single pane window.

The result was almost instant quiet, showing an average drop of 10 dB from the road noise, and far better than I expected. I measured it about 3 feet from the window:

- With the window closed, no secondary glazing: 42 - 55 dB (avg and peak)
- With the window closed and my secondary glazing: 32 -45 dB.

I made the readings from the NIOSH SLM iPhone app, which is one of the more accurate meters I've used. I averaged the readings out over 5 minutes each time and they were very consistent.

The best part, I later tried my Bose noise-canceling headset, and everything disappeared! Absolutely no noise whatsoever. Up till now when I wanted thinking/writing time I had to use a Youtube rain forest background through the Bose and often turn it up to 4/10 volume to drown out trucks and tire noise.

Now, near silence.

Without the Bose and sitting 3-4 feet away from the window the sound is very muted. Of course, large trucks and motorcycle mufflers are never completely quietened, but it is a considerable reduction there nevertheless. So I'm delighted.

As Randy often says in his replies to the questions on this topic: You need mass and air to kill noise. I agree and my setup proves it.

I was going originally to use 3/8" /10mm acrylic instead of the 6mm, but the extra weight made it impractical. For security, I have used two screws at the bottom of the 6mm panel to support it. The 10mm panel will take a lot more work to support.

So maybe 10mm is in the future now that I've seen how effective secondary glazing can be. I can only hope that the upcoming double glazing will put the final edge on the project, and I'm looking forward to that.

So thanks everyone for your contribution to my knowledge base!


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Re: Success! DIY secondary glazing story
« Reply #1 on: September 28, 2017, 10:13:50 AM »

Correction: 6mm is 1/4" - not the 1/2" I gave.


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Re: Success! DIY secondary glazing story
« Reply #2 on: October 09, 2017, 02:07:52 AM »


This morning I had double pane glazing installed. It comprised of a 6.3mm SoundStop acoustic glass - a specially designed laminate with soft plastic interlayer - a 10mm gap, and a 4mm pane.

The original dB measurement with 4-5mm single pane was:

- With the window closed, no secondary glazing: 42 - 55 dB (avg and peak)
- With the window closed and my secondary glazing: 32 - 45 dB (avg and peak)

The new measurement is:

- With the new double pane window closed and my secondary glazing: 29 - 37.5 dB (avg and peak).

So a difference of 3dB less on average, and a peak of 7.5dB less, though I think there are fewer trucks coming through at this time of measurement which skews the top end result.

The result is much as I expected and read about. I thought the SoundStop might have made more of an improvement, but the biggest difference is the secondary glazing and an air gap.

Randy S

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Re: Success! DIY secondary glazing story
« Reply #3 on: October 09, 2017, 10:46:03 PM »

Thank you for posting all this great feedback!!!
we at Super Soundproofing Co appreciate this type of feedback for other readers who have had bad soundproofing experiences to find out it can be done with cost effective solutions!.

Mass / Gap / Mass wins every time!

Thank you and Best Regards,

Randy S.


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Re: Success! DIY secondary glazing story
« Reply #4 on: January 24, 2018, 05:50:59 PM »

Thanks for sharing your experiences, Kevin. What kind of prior experience did you have with this? Just curious, as I'm trying to decide if I should do this on my own or not. I'm a total newbie.