Double-glazing, sound insulation and a yappy dog story

[HVB]

On a trip to the in-laws yesterday, I noticed an obvious difference in sound insulation between their house and a nearby newly-built house.

In-laws house:

1950's brick construction with uPVC framed double-glazing units installed about 5 years ago. The yappy dog perched in the window could not be heard barking from outside the house.

Newly-built house: Six months old, brick and block construction with, presumably the latest spec, uPVC framed double-glazing. The yappy dog in the window could be heard loud and clear, as if there was no window.

On the assumption that one yappy dog is probably as loud as the other, I was surprised at the obvious difference in sound insulation.

Presumably the neighbours in the new house must also be able to easily hear outside noises, whereas my in-laws are nicely insulated from the same.

My in-laws are notorious misers and I expect that they bought the cheapest windows they could find.

I'm no expert on double-glazing but I would have expected a more modern unit to offer at least the same level of sound insulation, if not better.

Would it be fair to assume that if sound can travel easily from inside to outside, so too can heat. This doesn't seem right - unless the new windows are just cheap rubbish, of course.

Anyone care to offer any thoughts on this?

HVB

[Calvin]

Sound insulation is compromised by even very small gaps. More modern double glazing is required to have trickle vents on most (all?) openings whereas older stuff wasn't and usually didn't. The sound transmission from the modern one will depend heavily on whether the owners had the vents open or not.

[Owain]

In-laws didn't pay extra for trickle vents? New windows probably have them as compulsory (they aren't, actually, but many builders would use them rather than any more sensible means of background ventilation)

Owain

[A.Clews]

Thus spake HVB ( [e-mail]) unto the assembled multitudes:

Are you sure the in-laws' yappy dog wasn't miming? They do things like that, y'know. Yappy dogs can't be trusted. ;-)

Seriously though, I have noticed quite a difference myself. My own house is brick-built and double-glazed throughout and pretty well sound insulated, but I've been in friends' new houses and you can sometimes hear the neighbours changing their minds. They just don't build 'em like they used to.

[sm_jamieson]

I thought the regs were tightening up on sound insulation between dwellings and between rooms - not sure about inside/outside. Anyone know about this ? Simon.

[RobertL]

The gap for optimal sound insulation is, IIRC about 100mm. that is too big for optimal heat insulation because you get circulating currents between the panes. So, poorer sound insulation does not mean poorer heat insulation, necessaorily.

For really good sound insulation I think you need three panes with asymmetrical spacing.

Robert

[Chris J Dixon]

Not only that, they should be different glass thicknesses, and not mounted parallel. Sound absorbing material should line the frame.

Chris

[Dave Plowman (News)]

Sound transmission through double glazing depends on two things effectively - the thickness of the glass and the gap between the panes. And for effective sound insulation you require a larger gap than is common

- and thicker glass.

I'd guess the older window had thicker glass.

Of course modern windows have trickle vents too which let through sound.

[The Natural Philosopher]

Trickle ventilation.

[Mogga]

There was something on TV ages ago about new builds not meeting regulations for draft proofing but no one has been in trouble for not meeting regs.

[Dave Plowman (News)]

A 9" brick wall - either solid or cavity - isn't *that* good for sound insulation. You'll hear normal conversation through it if it's quiet your side - but probably not understand it.

[HVB]

Thanks to all who replied... seems to be as simple an explanation as that.

HVB

[1501]

A one way trip to the vet for the yappy dog should quieten things down!