We recently have had a significant uptick in the number of enquiries for triple glazed sash windows and I thought it would be easier to write an entire article that covers all of the benefits of triple glazing over double glazing in terms of noise reduction and covering a broader idea of the costs in triple glazed sash windows as well as any constraints to triple glazed sash windows than go through all details on site. The general consensus is that roads are getting noisier/busier over time and flight path noise becoming more and more unbearable.
Looking to save money but get the acoustic performance? What can be done to make triple glazed sash windows effective in an original box frame?
One of the biggest difficulties we face with triple glazed sash windows is finding the depth in a traditional frame for the triple glazed unit itself. For triple glazed sash windows to be effective you need a good size cavity(air gap between the panes of glass, a minimum of 8mm but the more the better) in the first place. this means that if you’d like to install triple glazed sash windows in to the original frame you really ought to have a minimum of 40mm depth, some original frames have this and some haven’t. Don’t worry if not, there are still plenty of options and workarounds to keep the prices sensible. The other way that we can handle triple glazing is by over manufacturing the depth of the sash and then rebating the face edge so that we can get the overall depth required, this isn’t a sash repair, this is done in our workshop at point of manufacture. What this means is effectively cutting the corner out of the sash and that allows the sash to pass the edge of the frame. Don’t worry if you don’t understand that, here’s an example to make it clear in picture:
Notice I left the coffee cups in shot, we do much better work when tea and coffee is provided 🙂
On the inside it’s just a simple case of making the staff bead a little bit smaller with a draught proofing seal tightly and snug fit into it to ensure maximum noise reduction
What is the spec of triple glazed sash windows?
Most commonly triple glazed units for sash windows are formed with 6.8mm or 8.8mm acoustic laminate glass as a base for the soundproofing, a good sized air gap(as we mentioned 8mm as a minimum but ideally larger), and 4mm float glass. This is the base for a high quality sound proof unit on a sash window and if you would really like to know your glazing then please check the article highlighted.
Here’s a nice picture of an acoustic laminate triple glazed unit installed into an original sash. As you can see it’s quite thick. We typically manufacture our joinery as slender and elegant as possible.
As you can see from the unit two of the panes of glass are sandwiched together. In between these two panes of glass is a plastic film that joins them together. Incidentally, this type of glazing is extremely good for safety and security as well. So if you’re looking for a security upgrade then this kills two birds with one stone.
Having different thickness glasses stop different sound frequencies which helps to maximise the efficiency of your triple glazed unit. Incidentally, the newest idea to maximise noise reduction is two panes of acoustic laminate rather than one with a 4mm float pane of glass But this can be a little prohibitive in a sash window because of the sheer weight of the window that needs to be counterbalanced. That said, the sash can always be put on spiral balances to reduce the cost of mechanism but it’s well known that this mechanism is as long lasting or quality is a traditional sash cord and weight. Sash cords can literally be replaced by the homeowner, whereas spiral balances are far more difficult and require a specialist. Finding such a specialist is rather difficult as well, we are just one of a handful of London sash window companies that will replace spiral balances or springs as they are referred to in the trade.
Do triple glazed sash windows look any different to original single glazed sash?
The great thing about our triple glazed sash windows is that over the years we’ve managed to develop them so they almost look like single glazing front on. If you’re to look at are triple glazed sash windows from straight you would hard-pressed to tell the difference between them and single glazing. The biggest give away, is the fact that there’s a reflection from the multiple panes of glass, otherwise you wouldn’t really know that these have actually got a triple glazed unit inside, much in the same way as we manufacture double glazed windows.
Above is a picture of a triple glazed sash window that’s been installed into the original frame. This has undergone the treatment mentioned above of having the face edge of the top sash rebated to allow for a thicker sash that the frame could normally carry, this way we are able to maximise the size of the of the triple glazed unit and the result was impressive, especially since this property was over a flight path. Whilst it didn’t entirely eradicate the noise of an aeroplane, it really made a significant difference and dulled the sound to the point the noise was in the background. You won’t cut noise to zero because as efficient as the glazing is, the noise can still come through walls and roof too but it’ll certainly improve things considerably.
How much do triple glazed sash windows cost?
Typically triple glazed sash windows cost around £1300-£1500 when installed into the original box frame. This represents around 35% more than double glazed sash windows. This cost is simply a case of the glass being more expensive as well as there being an additional counterbalance cost. If you consider the 8.8mm glass is double the weight of 4mm glass, it considerably increases the amount of counterbalance lead required to make the window stay put when you open it. If you entirely replace the sash window including the box frame as well then the cost will start from anywhere from £2500 pounds per sash window.
There is an additional benefit to entire replacement, and that is that the noise reduction is slightly better because where we manufacture a perfectly square new frame, the sash seals to the frame a little bit better giving that little bit extra performance. Ultimately, triple glazed sash windows into the original frame is much better value for money but not quite as effective as an entirely new triple glazed sash window. Pound for pound though, triple glazing into the original frame is much better value for money when considering the decibel reduction per pound spent.
Price isn’t an issue, I just want the best noise reduction triple glazed sash windows
If you’re really struggling with noise pollution and in certain circumstances I’m well aware of the situation where customers literally can’t even sleep in their own home at night, and you want the absolute highest quality noise reduction possible then that would be to have two panes of acoustic laminated put together as a quadruple glazed unit. This seriously cut the amount of noise pollution but the drawback of course is the price. This lemon glazing can set you back from anywhere from £3500 per window if entirely replaced.
There’s little point in using the original frame in a situation where you’re going for Absolute noise reduction because you can’t get the perimeter seal to be as perfect as a new There’s little point in using the original frame in a situation where you’re going for absolute noise reduction because you can’t get the perimeter seal to be as perfect as a new box frame. if you understand how acoustics works, then you’ll realise it might be worth actually sealing the window closed as well.
But one must consider that there needs to be a fire exit as well as conforming to all regulations and we cannot make an illegal install. If you have more than one window in your room then it might well be worth sealing one shut so that you can absolutely maximise the noise reduction and have no gaps around the glazing. Amazingly the gaps around glazing contribute to a significant percentage of all of the noise pollution that actually gets through the window. That’s why installing a comprehensive draught proofing system is so important in combination with this acoustic glazing. Once you’ve installed this triple stroke quadruple glazing, the next thing to do is to install a secondary glazed sash window over the top of this. This absolutely guarantees that you minimise the amount noise coming through the window entirely. All that will be left, is the noise that comes through the walls and ceiling.
If you’d like to discuss you a triple glazed sash window requirements, or noise reduction, or acoustic glazing then please call or email us today.