Jump to content

Shattered Double Glazing Unit


Recommended Posts

Hi paulb


You seem to be one in the know regarding certain glazing prices, can you enlighten us any as to where these examples are available?

What type of glass would be in the triple glazed units you've mentioned?

I certainly agree that a grand for the glass and fitting is very OTT but it would probably be because of the type of glass used e.g. 6mm x 6mm, Heat Soaked, Thermally Toughened Soda Lime Silicate Safety Glass would surely carry the major part of its total?

Link to comment
Share on other sites

Good to hear from you again Suffererof1crankymofo,


The original window was suspected to be 6mm glass outside & 4mm inside?   


the location and size usually dictates what spec of glass is used, the fact that your unit is toughened on the inside means that it it either in a door, adjacent to a door or has a cill that is less then 800mm from the floor, if it isnt you can just use normal 6mm laminate

Link to comment
Share on other sites

Hello again Hobbiniho


Yes, you are perfectly correct i.e. ours does qualify for the use of toughened glass being less than 800mm from the floor.


While you're on, do you think the glazing units in paulb's £309 example is more likely to be laminate and any idea where one can purchase them? 

Link to comment
Share on other sites

probaly not but try these https://sealedunitsonline.co.uk/regular/default.aspx?gclid=CjwKCAjw0N3nBRBvEiwAHMwvNu83lFnT-O2mb59_rMKKChs4NY_q-S5d-mngPv2Digk7UN_YjwEr1BoC5BgQAvD_BwE


or these



they areboth coming out at between 250-350. if just replacing the glass then its a few minutes work. however i would really want to know why it broke first . either structural movement. oviously the worst option. a frame fault or glass fault. where the spacers used was it able to expand and contract. im no expert i did replace our previous houses windows myself. i was surprised the glass was cheap compared to the frame. make sure its measured accuratly an error we had. 

Link to comment
Share on other sites

Many thanks for the information paulb!


Yes, I also want to know why it broke as well but without utilising some kind of expertise in that type of field it may never be known?

Nickel Sulphide Inclusions (NiS) have been suggested but that has never (as yet) been confirmed and structural movement simply isn’t visible.


I've waited most of the day for certain information from both these companies (see paulb's links) but sadly still wait, so have decided to post my findings so far:


Looking on the links paulb has kindly supplied, I've found prices for our possible replacement by estimating some sizes etc:


No 1: 1400mm x 1500mm

(Black Spacer/Supplies but doesn’t advertise Heat Soaked so I’ve requested a quote on their 6mm x 6mm version.)

6mm x 4mm Toughened/Argon filled/28mm thickness = £308.70 Inc VAT

6mm x 6mm Toughened/Argon filled/28mm thickness = £409.50 Inc VAT


This company doesn’t actually advertise any Island delivery but delivery to any location within UK mainland cost e.g. 3 days at £180, 7-10 days at £60, up to 14 days £30, up to 28 days £15 (all excluding VAT) & up to 45 days FREE.


No 2: 1400mm x 1500mm

(Black Spacer/Doesn’t advertise Heat Soaked either, so I’ve asked via email if they can supply that? I’ve also asked if they can supply 6mm glazing as I don’t see that on their website?)

4mm x 4mm Toughened/Argon filled/28mm thickness = £238.72 Inc VAT

4mm x 4mm x 4mm Toughened/Argon filled/28mm thickness = £342.11 Inc VAT


No Island delivery advertised again but by making the delivery ‘Scottish Highlands between 8am – 6pm it makes the total costs £298.76 Inc VAT for their double glazing & £484.61 for their triple glazing.


It is clear that some savings could indeed be made i.e. compared to the local quotes I’ve already been given but how much would surely depend on what is required, chosen or requested and transportation/shipping to its final destination still needs to be factored in.


Out of what I see on offer, my replacement preference would be either the 6mm x 6mm toughened double glazing or the 4mm x 4mm x 4mm toughened triple glazing but preferably with Heat Soaked Toughened Safety Glass which I still await possible quotes on. 

Link to comment
Share on other sites

how old was the broken widow.could it have been something as simple that if one pane was diffrent to the other then it could expand and contract at diffrent rates. hence it broke. those where just examples and not me saying to use them. is it covered by your insurance. the troubleif you just replace it then it may happen again. is it possible that something hit it which of course would then make it an insurance claim.

Link to comment
Share on other sites

Hello again paulb,


The broken glazing is almost 3yrs old, we in fact paid the majority of that renovation billing in September 2016.


It is suspected that the glazing unit was 6mm x 4mm Toughened Safety Glass but our paperwork does not tell us any detail, the supplier/contractor/builder has shown no interest, the supplier/distributor says its too old to be found in his paperwork and the manufacturer won't deal directly with the public only with whoever in the trade purchased & ordered it.


I know you only gave the links to those companies as examples and fully understand that you are not saying to use them, so please don't pick me up wrongly I am indeed truly very grateful for the information you have supplied.


This incident is not covered by our insurance but by changing the wording to accident, accepting the blame and altering the series of events a claim could well be approved if one had chose to follow that pathway.


I agree it may well happen again but if I go down the road of replacing like for like i.e. if I could definitely prove its exact construction, I'd constantly live in fear that its just about to happen.

So what's left e.g. make the replacement 6mm x 6mm Heat Soaked Toughened Safety Glass and possibly live in a slightly better atmosphere thinking that as we've improved on the glazing units version it really shouldn't happen again?

If it happens again after all that, I think we would have to be having some kind of major problem i.e. especially if nobody else is experiencing this type of issue.  

Edited by IGU
Link to comment
Share on other sites

I thought the following from an Australian website quite interesting:



Causes of exploding glass:

Incorrect Installation: While glass is being moved and installed, it is easy for the glaziers to nick or chip the edges of the glass with various tools. These small nicks or chips may not result in immediate breakage. However, over time, as the glass expands and contracts, stress concentrations can develop around the nick, leading to breakage. In the case of tempered glass, the entire unit usually breaks.

Binding in the frame: Glass expands and contracts with changes in temperature, so almost all modern glass is set on resilient blocks at the bottom and with space for expansion at the sides and top. If no space is provided at the perimeter of the unit, the glass will bind against the frame, causing internal stresses to develop in the glass which can exceed the strength of glass, resulting in breakage.

Manufacturing faults: Nickel sulphide inclusions can be present in the glass. The most common cause of these inclusions is the use of stainless-steel machinery in the glassmaking and handling process. Small shavings of stainless steel containing nickel change structure over time and grow, creating internal stresses in the glass. This type of breakage is almost always found in tempered glass.

What is nickel sulphide?  Sodium sulphate is added during float glass manufacture to promote bubble removal from the molten glass during the melting process. When combined with nickel contamination, sodium sulphate forms nickel sulphide (NiS). Nickel contamination can be caused by: an impurity in the raw materials; contamination during the storage and handling of raw materials; or contamination from the float line equipment, e.g. firebricks and burners.


Improving performance: Heat Soaking Toughened Glass

Heat soaking is a test process that attempts to eliminate nickel sulphide inclusions, which can cause spontaneous fragmentation in toughened (tempered) glass.

What effect does nickel sulphide have on glass? During the manufacture of float (annealed) glass, the raw glass materials are heated to around 1100°C and the nickel sulphide consequently reduces in size. When the glass is slowly cooled during the annealing process, the nickel sulphide expands back to its original size. This expansion does not interfere with the properties of the glass. However, an issue arises if the glass is toughened. Glass is heated to around 600°C during toughening, and the nickel sulphide consequently decreases in volume. To create toughened safety glass, stress and tension is induced in the hot glass by rapidly cooling it. Unlike the slow cooling of annealed glass, this rapid cooling arrests the transformation of the nickel sulphide. The nickel sulphide will expand to its original size over time. If this expansion occurs in the area of the toughened glass that is under tension, it will cause the glass to fragment.

The presence of nickel sulphide is quite rare: Approximately one ‘stone’ of nickel sulphide is present per 8 tonnes of raw glass (although it can come in batches). The incidence of nickel sulphide varies from manufacturer to manufacturer with estimates ranging from one stone per 8 tonnes of glass to one stone per 13 tonnes of glass and some suppliers having a more frequent incidence than this. Nickel sulphide can cause glass to fragment at any time in the product’s life – from a few moments after thermal treatment to years after glazing installation. Nickel sulphide can also affect some types of heat strengthened glass.

Essentially, heat soaking artificially ages the glass and although not 100% effective, will significantly minimise the risk of glass exploding at a later stage. This process is an ‘extra’ and can be completed by a glass manufacturer upon request. Due to this extra processing, Heat Soaked panels are significantly more expensive.

Link to comment
Share on other sites

Hello Nigel Bridgman-Elliot,


I certainly can't comment on glazing units being rated up to 120mph winds but maybe others can?

I can tell you that this glazing unit used to 'flex' its inner pane on certain occasions during our local windy weather periods?


No water was ever noticed inside our unit but I can certainly see what you mean if it ever did and then froze!

Link to comment
Share on other sites

it should be covered by i think a fensa certificate. looking at the response from the builder and manufactorer im guessing it going to be one of the first 2.

its really easy to chip it if not handle very carefully. it would the act like a windscreen crack its going to slowly be expanding. with toughened glass as you would expect it will fail rather rapidly. i suspect it was not fitted properly. if the builder has not given you a cert it could be raised as an issue if you come to sell. plus its meant to have a guarantee with it.


all glass in double grazing should be upto at least pilkington k standard. its unfair that youve been left with this. can you get triple glaized with toughened glass. i probably would not be bothered by that nickel test. it really should not have been moving in the wind. argon filled would be better. 


a blown window when water gets in should not cause it to fail. it will lose some insulation value but thats it. its even fixable  not sure its done up here. 


ireally hope you get it sorted

Link to comment
Share on other sites

Hi paulb


Many thanks for your input!


Fensa was briefly discussed a few posts back with suffererof1crankymofo and it was discovered that it only applies to England & Wales.

Hobbiniho thought the Scottish equivalent i.e. “the building regs wont have any effect on the warranty of the windows, the building regs are only worried about u value, ventilation requirements, emergency escape requirements and location of safety glass etc


Does anybody know if providing certifications or guarantee’s is the normal by the builders?

They were certainly never given or offered by ours!


The list I obtained from the websites that you so kindly supplied did indeed have triple glazing that was 4mm x 4mm x 4mm Argon filled/Toughened Glass but neither company ever came back with a price on the ‘Heat Soaked’ version.

Link to comment
Share on other sites

My apologies,


  • 2002 Debut for FENSA

    In April 2002, the UK government authorised the creation of FENSA (Fenestration Self-Assessment Scheme). The first and most well-known Competent Person Scheme for the window and door installation industry in England and Wales.


    But the methods used north of the border should be noted.



Edited by George.
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...