wanna see the 6x3 window we built?

[seaneldon]

we finished the frame yesterday. two panes of 1/2" glass come in on wednesday. i'm on my way to the studio now so i'll take a "finished" picture of the frame...but here's how it started:

 

inside the existing wall, there was a regular "home" glass window for some reason, as well as a large pane of plexiglass right next to it. we had to make a cut to remove all of that. let's just say i put a vaccuum cleaner through it.

 

[Warhead]

Sean, just curious to know: isn't it better to have different thicknesses in glass so that they don't resonate the same?

 

War

[seaneldon]

i've heard that, but the three windows i've built before had 2 panes of either 1/2" or 3/4" glass and i never had/heard a problem. the two panes are at different angles, however.

[Phil O'Keefe]

One thing about angling the glass is that it introduces reflections - both sonic and visual. Another area of potential concern is that angling the glass usually decreases the distance between the two panes, and also the internal cubic volume of the air cavity - both of which can have acoustical ramifications.

 

The recommendation for differing densities / thicknesses on the two glass panels is generally a good one IMO, but there are many factors to take into consideration. The size of the window opening, the volume and depth of the cavity and the corresponding resonant frequencies, the thicknesses of the glass panels, the angles they're installed at and the resonant frequencies of those panels are all going to have a bearing on the effectiveness of the window insofar as acoustical isolation as well as visibility through the panel.

 

My window is constructed with two double laminate glass panels - which I also highly recommend, because laminated glass measurably increases the STC of the window. Of course, you need to make sure it's airtight, and putting some silica packs inside, between the panes, has been suggested to me in the past; especially if you're using wood (as opposed to metal or vinyl) frames - I was told it will help prevent interior fogging if any moisture is absorbed into the wood via the humidity in the air. I have no idea from actual test data if it really helps or not... but I can't imagine it would hurt anything.