Acoustic double glazing units?

[jayc89]

For context, we live on a rural road, it's not busy by any means, but it's long and straight, which means cars but lorries and motorbikes in particular, come thundering down it. Our living room and, above it, our bedroom front onto the road, so we're looking for some better glazing units to quieten it down a bit. 

 

The frames we have (Rehau RIO), accept 28mm units, and we had been leaning towards 4mm/14mm/10.8mm acoustic laminate, the supplier suggests this would provide [41 (39;36) dB], which is probably the best we can expect for double glazing units in a PVC frame. 

 

However, we live in a traditional building and astragal bars would look the part - if we add these, the supplier can only offer 4mm/18mm/6.8mm acoustic laminate units, which they are suggesting provide the same Db rating - I call BS, and I'm almost certain they wouldn't be as good at deadening the lower frequency noises we care most about. 

 

So our options are:
- 4mm/14mm/10.8mm acoustic laminate with Georgian Grid, which don't look as good, IMO, but I'm pretty confident will provide better sound insulation

- 4mm/18mm/6.8mm acoustic laminate units with Astragal Bars, which will look better, but, I'm pretty sure won't be as performant for what we're looking for

- buy somewhere else

 

Am I over thinking this, or should I stick to my guns and find somewhere that can do 4mm/14mm/10.8mm acoustic laminate with Astragal Bars?

[Mike]

After playing with glazing simulators, I found that this spec provided the best performance within a standard frame: 4mm standard laminated / 16mm argon-filled cavity / 6mm acoustic laminated = Rw (C;Ctr) 39 (-2; -6) dB.

See my post at https://forum.buildhub.org.uk/topic/32665-further-sound-insulation-through-bookcases/#findComment-480975 for more. BTW, the argon is for thermal performance, not sound.

 

It does give very good sound resistance against regular traffic (provided you don't stick trickle vents in the frame), but not enough to kill the noise from boy racers / revving engines / stupidly loud exhausts. To kill that you'll need specialist secondary glazing.