Loft conversion noise issue

[jelboy]

Hi guys
Need some advice pls
We recently had a loft conversion done (bedroom & en suite) and are experiencing a lot of traffic noise from the main road 50 yards away..
I am a heating engineer by trade and used to be a sound engineer (go figure) so am aware of the way sound travels and how builders work etc...

The traffic noise emanates from the front of the building (pitched roof) which consists of tiles, felt, celotex and a plastered finish...
It sounds like the Velux are letting a lot of sound in and they have said try shutters (not blinds-we already have them), or new sound resistant glass..
My question is tho... If we fit shutters (£650 ish) will that cure the issue??
If the sound is coming thru the plasterboard wall then would it not be better to put sound proof board over the existing?

Any help would be greatly appreciated please

Thanks

Jelboy

 

[Architexeter]

Depends on the volume and frequency but from what you say it is airborne so you need to add mass. Try blue "SoundBloc" plasterboard from British Gypsum (or equal) over existing. Its a bloody heavy board!

If you have a void behind the vertical studwork walls consider getting some/more quilt to prevent reverberation.

Hope that helps

 

[freddiemercurystwin]

Well as an ex sound engineer I guess you would know that its a bit hit and miss, you could add this or that but whether it makes much difference and whether it was money well spent is completely individual and nobody (repeat nobody) on here can say for sure.

 

[Blagard]

Why not go to one of your old mates still in sound engineering and borrow a meter with a directional microphone. You may be able to positively identify the part of your structure that is the cause of the problem.

As for the shutters, well they have no dB reduction rating I am aware of, so don't expect a lot from them. Any mass put in the way of sound will help. You could measure before and after levels and let us know if it is worthwhile

 

[freddiemercurystwin]

As for the shutters, well they have no dB reduction rating I am aware of, so don't expect a lot from them. Any mass put in the way of sound will help. You could measure before and after levels and let us know if it is worthwhile

Yes but this is the issue, what is worthwhile for you or I may not be for the OP, or he may be overjoyed with the result. db levels mean very little really.

 

[jelboy]

GGL *** 3059 window with closed vent flap + shutter open = 56db
GGL *** 3059 window with closed vent flap + shutter closed - noise level = 45db
Noise level difference = reduction of 11db

Thats quite a lot me thinks..
Whst about sound proof board over the existing?

J

 

[jelboy]

Basically Im asking whether its better to soundproof the walls or the window???

Any one have exp of this pls?

J

 

[catlad]

You could buy some 8x4' polystyrene 2" thick and then fit it to your window reveals as a test before you spend a lot of money on blinds.

 

[Blagard]

Yes but this is the issue, what is worthwhile for you or I may not be for the OP, or he may be overjoyed with the result. db levels mean very little really.

There is something in what you say because the frequency has a lot to do with it. My understanding is high frequencies are often more irritating, but you may hear the rumble of low more often. I was interested to note the OP seems to have some information on the shutters sound reduction performance.

traffic noise covers almost the complete spectrum of sound people hear. Typically with lorries at the low frequency end and motor bikes at the high frequency end and all sorts in between. Low frequencies carry well over distance, high frequencies don't However a general loss of 11dB is going to make some impact across the shutters and it is about the only "measure" we have. But of course such reduction is virtually useless if the problem is elsewhere.

Regretably I am unable to offer any advice from a personal perspective these days as I am totally deaf unless I am switched on! - Now a cyborg with electronic hearing (I have a cochlear implant).

 

[Blagard]

Basically Im asking whether its better to soundproof the walls or the window???

Any one have exp of this pls?

J

Many moons ago I lived in a property that was on an major A Road (just 30 feet away with not even a garden wall in between). Traffic noise was a major problem. Walls on this property were almost certainly 9" solid brick with no cavity to speak of. Windows single glazed in wood frames.

Secondary Glazing was installed to create an approx. 50mm cavity with reveals lined in an accoustic absorbent board. The effect was a staggering improvement straight away with a major reduction in traffic sound.

Modern double glazing is essentially for thermal insulation with a relatively narrow gap between panes. It certainly has a significant impact on sound but not as much as a specific sound focused solution.

The major problem you have is that there is very little mass in the "Walls" of your loft and I would suspect that you would need to add to both walls and window to get an overall improvement.

Consequently I was quite serious about using instruments to try and identify the most problematic area to get some improvement. I acknowledge Freddie's comment that even with a an improvement in a technically loud area, it may not be to the sound quality that affects you most!

 

[jelboy]

Thanks guys, all good comments
I have tried the insulation over the window openings, but not to any great success... Had to keep them on... Nails worked but not too well
Im stuck at the mo... As you all know, any gap will let sound thru, so even a temporary test doesnt really work

Hmmmm...

Had a plasterer round who said that adding extra board wont help

Not sure why

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARRRRRRRRRRRRRRRRRRRRRRRRRGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[Blagard]

On DIY SOS the Big Build, they helped out on a House in Nottingham
The Big Build - Nottingham

The games room was lined in dark coloured layer of sound proofing material about 20mm thick. and covered by the plasterboard. It seemed to have very impressive soundproofing properties if you could find out what it was it may be what you need.

 

[geraldthehamster]

Thanks guys, all good comments
I have tried the insulation over the window openings, but not to any great success... Had to keep them on... Nails worked but not too well
Im stuck at the mo... As you all know, any gap will let sound thru, so even a temporary test doesnt really work

Hmmmm...

Had a plasterer round who said that adding extra board wont help

Not sure why

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARRRRRRRRRRRRRRRRRRRRRRRRRGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

You have my sympathy. I have a similar issue in the first floor of my dormer bungalow. We ripped everything out and effectively it became a fresh loft conversion. Having battened the rafters to make them deeper, I insulated with 5" celotex between and under. Celotex has no sound reduction qualities at all. The sloping part of the wall (which is most of it) was boarded with one layer of Soundbloc plasterboard and a second layer of normal plasterboard, and skimmed. I suspect a wall needs more solid volume than this, to be soundproof. if I can ever justify the expense of re-roofing, I'd try sarking boards under the new tiles.

There are 3 velux windows on the traffic side. The ceiling has about 18" of fibreglass roll insulation above it. I still get traffic noise. I suspect some of it might be coming in at the eaves, because we get it downstairs as well, where we have proper walls. I think the window reveals are also a weakness. I'd considered secondary glazing over them, in a wooden frame screwed through the plasterboard and insulation to the rafters - given the sloping roof and the fact that it's at head-banging height, it would have to be perspex rather than glass.

It's not loud enough to deafen me I still find it bothersome, and I'm interested in comparing notes!

Cheers
Richard

 

[Deluks]

The celotex is likely aggravating the problem, transmitting and amplifying the noise. If you could remove it all at the front, and replace with mineral wool slab, then reboard with a couple of layers of 12mm board, you might get somewhere. Changing the velux sealed unit for a triple, or thicker paned unit will also help. Plus as mentioned, the eaves will be a weak point.

 

[geraldthehamster]

The celotex is likely aggravating the problem, transmitting and amplifying the noise. If you could remove it all at the front, and replace with mineral wool slab, then reboard with a couple of layers of 12mm board, you might get somewhere. Changing the velux sealed unit for a triple, or thicker paned unit will also help. Plus as mentioned, the eaves will be a weak point.

Removing installed insulation with tiles on one side and a plastered finish on the other isn't exactly practicable. Nor is mineral wool going to provide the same U values. That said, if I were doing my job again I'd have included both. What the OP presumably requires is solutions that can be applied now, not that could have been applied during building.

I'm planning on revisiting my eaves by cramming rock wool tightly between ceiling and floorboards in that area - ensuring of course that ventilation isn't compromised.

Cheers
Richard