In article om,
writes
Dear Group,


I am in a situation where I need to minimise sound transmission into a
room (noises such as sirens and raised voices, not low frequency or
road noise).

There is no option of secondary glazing due to the fact that there is
a Juliet balcony. The only option is 'upgrading' the existing 24mm
(4-16-4) sealed units. I appreciate this is not the ideal option.

So, what is the ultimate 24mm sealed unit for sound reduction?

Different thicknesses of laminated glass? Gas filled? Sound insulating
spacer bars?

Many thanks for any advice/experience that anyone can share.

Pilkingtons had some great pages on their Asia/New Zealand site with
tables of construction vs attenuation but the page is no more.

From memory, the best of the DG options was 6.4mm laminated inner,
4mm plain glass outer with appropriate spacer to make finished thickness,
the dissimilar glasses broke up resonant transmission. I think the claimed
reduction was 50%+. I see Pilks have introduced Optilam Phon which
claims to absorb more sound by having a softer plastic layer than that of
normal laminate so that would probably be the ideal inner.

There may be more info at http://www.pilkington.com but they don't half
make it hard to find. If it bothers you I imagine they will do Optilam Phon in
low-e as well. Be sure to buy from/as trade if you can.

As I'm sure you're aware, the window seals will need to be pretty airtight to
get much of an improvement, if the noise doesn't already reduce by a
dramatic amount as you close the window the last 5mm & latch it then
you probably have a suspect seal.

If you have trickle vents, forget it unless you fancy filling them with builders'
foam.
--
fred
Plusnet - I hope you like vanilla