Safety glass in doors is thickness an issue as well?

[G]

My mother has two doors in her house with missing or cracked glass.

They are old doors and it appears the rebates are a bit shallow for thick glass.

Do we in fact need thick glass to be fitted, given that for safety we can now use laminated, toughened, or film coated glass? To fit thicker glass would mean replacing the doors.

Does it today need to be thicker to be strong enough not to break under its own weight or something?

Or are all the safety glasses intrinsically thicker?

My Mother has been told by her usual builder that plain glass is OK thinner where obscure is not. Is this because it can be thinner for the same strength? Or is patterend intrinsically thicker?

thanks

[G]

Having now read more about this, it eappears what we have is old doors with rebates for 4mm glass. Can I now purchase patterned 4mm glass of a safe kind (toughened or Laminated or filmed) and use it in these doors. If not patterned, can I use4mm plain glass of a safety glass kind?

I see Pilkington do make patterned toughened 4.4mm glass, for example. The question is, is 4/4.1mm thick enough or is it just going to break? The pane in one door is pretty much the full size of the door minus about a 4" all round frame. The other door has a dividing bar down the middle, but is full height.

[Bob Mannix]

example. (You need Dopey acrobat)

Bob Mannix

[G]

Thanks for your trouble finding that. I did in fact find it on my travels, and understand I need safety glass.

The Question is: how thick?

There appears to be no safety rule regarding thickness, provided you use safety glass of some sort. Will it break under its own weight if I use 4mm toughened glass in a single door-sized sheet? Will it break under its own weight if I use 4mm toughened glass in half-door-width sheets?

I know I can buy 4mm toughened glass, bot plain and patterned. I suspect I cannot buy 4mm laminated because it would be hard to produce? Is this true?

[Ziggur]

4mm toughened glass is perfectly acceptable for use in your door. It is the most commonly used thickness. 4mm laminated (nominally 4.1mm) is a bit thin for a single sheet in a door. (An area of heavy traffic)

The "Safety" designation is not that toughened glass will not break but that, IF it does, it will break into tiny pieces which will not seriously cut rather than into dangerous shards

[Dave Plowman (News)]

However, toughened glass is *vastly* stronger than ordinary (or laminated) under most circumstances - hence its name.

[G]

Thanks for these two replies which realy clear it up for me.

One thing remains: I see Pilkington makes 4.1mm patterned AND toughened glass, made by rolling the pattern into the glass. Is this going to make the glass too thin in the thinner parts of the pattern to be safe in a door sized sheet? Or: Is patterned glass of the same nominal thickness normally considered weaker than the equivalent plain? And: If toughened is this an issue anyway in this size sheet.

A friend of mine had his house attacked once by youths throwing bricks at his windows, toughened glass - they bounced off. Equally I once stored some toughened double glazing units in my shed on edge - one of them got stressed on the edge and "went" - crazed all over. Now I know to store it flat.

Thanks.

[Ziggur]

Dave

Does it ever occur to you before you post that, although you may be the group's resident "expert" on expensive power tools, there are some in here who have moderate knowledge on other specialist topics?

Toughened glass has, on average, 4.5 times more resistance to breakage by impact than normal annealed glass. That resistance is measured by swinging a leather bag filled with lead shot on the end of a chain at the glass surface. This archaic test is the current British Standards method. It confirms that if the glass is impacted by a football or a head or a similarly large object it will resist breakage by a factor of "up to" 5 times the level for annealed glass. HOWEVER - most burglars and all glazing professionals know that this extra strength is limited to these conditions. A hard tap with a hammer and nail or a jab with a steel bar) near the edge of a toughened glass pane will cause it to break more easily than an identical blow on annealed or laminated glass.

Bottom line. The OP asked about thickness and the risk of breakage. SAFETY glass is about SAFETY, not SECURITY. It breaks, but not dangerously.

Join me for a trip around a Pilkington or a Saint Gobain factory and then we can talk about De Walt on the way home :)

[Ziggur]

Good question.

The pattern is embossed onto the normal thickness and therefore the finished product has bits which are thinner. The manufacturers do not produce all available textures in the toughened product because some deep patterns leave pretty thin areas. The short answer is that textured toughened glass is not as impact resistant for a given thickness as plain glass.

The good news - if you buy textured toughened glass in the UK it would be very unusual for it not to carry the BS6206 kitemark and it will therefore be safe in your door. (Unless Dave P tries to drill a hole in the corner with his DeWalt SDS!)

Regards

[G]

Actually your and Dave Plowman's post together illuminated the subject greatly for me, Dave underlining rather than contradicting your advice. I have picked previously up that safety and security are different things. I am not worried about security in this instance, only working strength, and safety. My last post above gives an anecdote that of course fits your information on glass strength. I have practical experience of how weak toughened glass can be when provoked!

What I want to do is see if we can't replace the annealed glass that -was- in an existing door at my Mother's house with new glass that will not break in what will probably be careful daily use by my Mum, and IF it does break, causes little or no injury. My Mum's usual general builder wants to replace the whole door, saying that the rebate in the existing door will only take

4mm glass. It seems to me from what I have read that 4mm toughened is OK for my application. I am left wondering if patterned 4.1mm toughened is still strong enough as the pattern must surely weaken the pane, due to the pattern making the glass less than 4.1mm in any grooves?

[G]

Safe, but also with enough working strength?

I am now left wondering why the builder thinks plain 4mm glass is OK, but patterned glass is not. Perhaps he thinks you can't get 4.1mm toughened and patterned glass?

[Dave Plowman (News)]

I don't claim to be the group's resident expert on anything. I leave that sort of claim to others. Sadly, it's often no guarantee of a reply the average non expert punter can understand.

Which is why I added the comment to your post - which gave the impression that toughened was no stronger than normal glass, only safer.

So which part of 'vastly' is now wrong?

Any glass fitted in the conventional manner into a door has near enough zero security - regardless of type. Indeed, few ordinary doors of any type will stop a determined burglar.

Just who's post were you reading? I made absolutely no comment about security. If you choose to read that into my post, that's your affair.

No thanks. I doubt we speak the same language.

[Dave Plowman (News)]

Thanks. That's all it was meant to do, as I didn't think it quite clear. Even the best 'expert' in the world may not express themselves clearly to others - often assuming too much.

[GD]

How many makers of glass are their in the UK?

I always seem to find nothing but those age old Pilkington patterns, for example?

[Ziggur]

The majors:

Pilkington in the UK

Saint-Gobain and Glaverbel imported from Germany/Belgium. Both have web sites

Most UK glaziers use Pilkington for texture glass, their patterns are frequently updated. You can check the range on their web site.

Glaverbel have some nice patterns.

[Pete C]

Hi,

What is the door made out of, can the rebates be increased?

Patterned glass has lower average thickness for a given nominal so must weaker, plus any stress on the pane isn't evened out so much.

How about polycarbonate, or wired glass? Also toughened glass with a safety film would prevent falling through the door if it broke.

Another factor with all these options is means of escape in a fire.

cheers, Pete.