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Best route for Acoustic Window Performance

Discussion in 'Windows and Doors' started by GeddyMortgage, 18 Jan 2021.

  1. GeddyMortgage

    GeddyMortgage

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    Hi all,

    In a property we've recently moved into the front master bedroom (standard double glazed) window overlooks a main road that's 20M away or so and a motorway 200M away or so, both can be heard whilst from the bed, which has become frustrating.

    I bought a sound level meter and measured that with the bedroom windows open, the ambient noise (due to motorway) was around 52db, cars going by was 66db-ish and trucks going by was 72db or so.

    With the above in mind i'm looking at the most effective option for reducing the noise levels and had some questions for anyone who's happy to recommend. Options so far are :-



    :- Swapping the double glazed window for a 28mm Acoustic Laminated one. I've been recommended the 6.8mm variant based on diminishing returns above that thickness.

    :- Swapping the double glazed window for a 36/40mm Acoustic Laminated one. Hazy on details of this.


    :- Secondary Glazing 100mm-150mm gap from the main unit, leaving the double glazed units as they are.

    :- Secondary Acoustic Glazing, same as above.


    Am I correct to assume Adding acoustic secondary, would offer more sound reduction than swapping the main units for acoustic lam? Or does it not work like that?

    (photo of window attached for ref)

    bedroom_window.jpg


    thanks so much,

    M
     
  2. Tigercubrider

    Tigercubrider

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    in my experience, secondary double glazing will have the most effect. "done properly" it should be at an angle to the other glass but hard to do. The bigger gap the better.
     
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  4. GeddyMortgage

    GeddyMortgage

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    Thanks, by that rationale, is there any benefit in the secondary being acoustic/acoustic laminated? It's certainly more expensive than double glazing.
     
  5. Notch7

    Notch7

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    That would be a huge sheet of secondary glazing.

    I can tell you I used to make windows for music studios, they were typically 1200 x 1000 and about 200 to 250 deep. They had 2 panes of 6.3mm clear lam, one straight, one angled.

    They were used between studios and for in front of external windows.


    Do your windows have trickle vents? - they let loads of noise through -start by filling them up.

    Then check your windows are fully fraught sealed....any air gaps allow noise in

    Then check how well the window is fitted - is it fully sealed all the way around - any foam should be acoustic expanding foam.


    As an aside, please be aware, high frequencies are stopped by sealing gaps, however low frequencies are very difficult to stop and require both mass and isolation.

    Vehicle traffic creates quite a bit of lower frequency....so can you feel any vibration in the house?

    Stadia acoustic glass will help lower transfer of lower frequencies through the glass - If put your ear to the middle of the big pane you might feel the vibration.
     
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  7. GeddyMortgage

    GeddyMortgage

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    Regarding the size of the secondary, I believe it would be 3 sheets, one central and two side openers either side. Quoted so far for the laminated secondary option was around £1,100 fitted. Not convinced with secondary yet due to the accessibility and ugliness issues it could bring

    We don't feel much vibration. It's more a case of higher frequency road noise. Especially when it's wet outside.

    There are 3 bricks below that window that do not have any mortar in the joints. I assume the previous owner wanted to put trickle vents there and forgot. I will be pointing those. As for the sealing of the window, there is a gap between the window and window sill that does seem to be letting air in. it's only 1-2mm but when you put your ear to it, it's evident. Should that be caulked or siliconed?

    Lastly, one manufacturer came back with this option - 12.8mm acoustic laminate / 14mm Argon Cavity / 8.8mm acoustic laminate soft coat. 35.6mm over all thickness. 47db Rw / 40db Rw + Ctr. - that sounds mega, though assume rather expensive.

    On doing a bit of reading online, I can see most standard 28mm double glazed units are around 25-30db so that would offer a big improvement.
     
    Last edited: 19 Jan 2021
  8. DIYnot Local

    DIYnot Local

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