Reducing road traffic noise by replacement glazing (renovation)

[thaldine]

Currently have what appears to be early 1990's double glazing.

 

Is an appreciable reduction in road noise likely to be possible by fitting new glazing specified with sound reduction in mind ?

Edited July 10, 2021 by thaldine

[Russell griffiths]

Is there such a thing as sound reduction glass, my father in law is getting new windand the salesman said they would use a film on the outer pane to cut down the noise. 

I scream bullshit, and think he’s a snake oil salesmen. 

 

I have been ordered by the wife to keep my nose out, so I have to keep it shut. 

Edited July 10, 2021 by Russell griffiths

[markocosic]

Absolutely.

 

Each piece of glass "passes" certain frequencies and "stops" other frequencies. You want different natural frequencies on each pane so that you're blocking as wide a frequency range as possible. Say 6 mm (laminated) outside and 4mm (plain) inside. Get the "security" frames too (with more latches/locks) as they pull the windows tighter.

 

A chunk of the noise will be airtightness. Try just taping up the current windows. That'll give you an idea of how much windows that seal will contribute. If frames are good you can just swap the glazing units for some with a narrower space and a laminated outer layer as an experiment in one room. Unlikely if it's early 90s and was cheap.

 

Be prepared for a lot of the noise to come through the rest of the building though! Single layer plasterboard ceilings full of lighting/wiring holes with the smallest amount of fluffy insulation above them do nothing compared with an airtight layer plus double layer plasterboard with a denser (mineral wool, dense cellulose) insulation above them.

 

The difference between my house (60s sieve of a cavity wall / single layer dot and dash / single layer ceiling with fibreglass above and cheap double glaze) and the new cabin (20 cm timber frame with OSB lining / mineral infill / 5 cm mineral overlay plus triple glaze) is astounding - but most of that is airtightness.

 

You won't fix vibrations coming up from the ground by fiddling with your building. Fix the root cause (fill the potholes, dig up the speedbumps, and get width restrictions in place instead - the SUV driving spacktards can't aim toffee so will slow down; and the more capable delivery drivers don't get docked pay for suspension damage but do get docked pay for body damage)

 

What will you do when the window is open? (MEV / MVHR so that you can still purge CO2 / breathe even with windows shut?)

 

[ProDave]

14 minutes ago, markocosic said:

You won't fix vibrations coming up from the ground by fiddling with your building. Fix the root cause (fill the potholes, dig up the speedbumps, and get width restrictions in place instead -

That is very true.  We live close to a B road, and the house generally keeps most of the noise out.

 

But what noise does get in, is the increasing number of quarry lorries going up and down the road.  Particularly the empty ones on their way to the quarry. They "rumble" a lot as they pass over a particularly dreadful stretch of road, and that low frequency rumble gets in, probably through the foundations? more than any other noise.

[Ferdinand]

If a new housing development is expected to be very noisy, they tend to planning condition on special noise-reducing ventilation devices rather than saying "TRIPLE GLAZED" - so remember that aspect too.

[ProDave]

1 hour ago, Ferdinand said:

If a new housing development is expected to be very noisy, they tend to planning condition on special noise-reducing ventilation devices rather than saying "TRIPLE GLAZED" - so remember that aspect too.

That reminds me, I once wired a house facing an RAF airfield.  It was stipulated that all windows facing the airfield were non opening, and all ventilation terminals must be on the other side of the building with noise reducing ducts.

[Mr Punter]

If the existing frames are OK, secondary glazing can be cost effective.  The glass sizes will be bigger than the primary glazing so have a different resonant frequency.

 

If you use a thick acoustic glass, which is laminated with an acoustic PVB interlayer, there will be a marked improvement.

[craig]

Just a few things here.

 

1: It’s not just the glass, great glass in s***e window just isn’t going to give great noise reduction.

2: In an openable window, the noise is going to travel between the frame and sash. More gaskets and better sealing of those gaskets is important.

3: Noise will travel around the glass and through the glazing bead area. Might be minimal but it does occur.

4: How the window is installed is a majorly important factor. Noise will travel past the frame and between the frame and building. 
 

PU foam on it’s on doesn’t cut it. It’s not a completely filled void when used and noise will travel past it.

 

I recommend using a compriband as well PU foam. This dramatically increase the performance level thermally and acoustically.

Edited July 10, 2021 by craig

[Temp]

When I was young they built the M3 motorway past our house. We were offered free double glazing but my father had already installed some. He asked if they would pay for what he had installed but was told it did not meet the required specification. Apparently the gap between the panes was too small. He was told it needed to be nearer six inches to reduce traffic noise. So he let them come and fit theirs which was indeed much wider. We ended up with triple glazing in around 1970. It slid open to allow access to ornaments and photos on the window sills. 

 

My understanding is that narrow gaps are best to minimise heat loss and wider gaps are better for opitum sound attenuation.

 

Google finds..

 

https://www.kjmgroup.co.uk/blog/soundproof-windows-secondary-glazing

 

Improving the sound insulation of a double glazed window can be achieved by:

• Having the widest possible cavity between panes of glass
• Differing the thicknesses of the two glass panes used
• Using thicker glass
• Using an efficient insulating window frame
• Using specially laminated acoustic glass.

The gap between the original window and the new secondary glazing is one of the most important things to consider regarding sound insulation. The most common thickness of glass in the original household single glazing would typically be around 4mm, unless the property is pre 20th century, then it could be 3mm. Double glazing cavities are generally smaller on older double glazing and are usually constructed with 4mm glass.

• So if the original house glazing is 4mm and the secondary glazing is 4mm, the gap would need to be around 150mm between the original window and the new secondary glazing for optimal sound insulation.
• With 6mm glass in the secondary glazing this gap could be reduced to 100mm.
• If the reveal (or window cill depth) cant accommodate a 100mm gap then laminate or acoustic glass like Stadip should be considered for maximum sound insulation.
• Acoustic glass is always the best option – the downside is the increased cost

[SteamyTea]

On 10/07/2021 at 21:59, craig said:

Just a few things here.

Can glazed area disproportionally affect which frequencies get though, so two smaller windows, matching the area of one, may reduce annoying noise transmission?  Reflectance and resonance and all that, which may make a film effective.

 

With coastal defences, they have stopped building curved walls and now build a barrier with rocks of many sizes and shapes.  This randomness allows more energy dissipation than a fixed design, works well and is cheaper.

 

https://glasstime.guardianglass.com/en/glass-solutions/sound-control/acoustic-performance-glazing

Edited July 12, 2021 by SteamyTea