After hearing something shatter just before 5am, Guy Heveldt grabbed a cricket bat and crept into the hallway.

The Radio Sport producer sneaked into his bathroom, but instead of surprising an intruder he was confronted with a floor covered in glass.

"The floor is just covered, the glass is everywhere."

Heveldt described the noise the shattered shower made as a "big bang" followed by a crackling.


"It's lucky no one was in there."

When the Herald relayed Heveldt's experience to shower expert Paul Bason, he knew exactly what happened.

"Bet it made a big bang ... it makes a hell of a noise and a hell of a mess."

Bason, who owns PK Showers, explained shower glass is toughened to withstand a range of water temperatures. It is rapidly heated and cooled over eight to 11 minutes.

And then when it does break, it explodes into about 50 pieces per square inch instead of large shards so it can only cause small cuts instead of large wounds.

Bason said he doesn't know exactly what causes the glass to "give up" but suspected it had something to do with a cool day followed by a hot night.

But the phenomenon is rare.

In his 15 years in the shower business, Bason has only replaced about 200 pieces compared to the "probable millions" which were installed around the country in that time.

Bason has even been next to a piece of toughened glass when it's exploded and said it's not too dangerous, he just suffered a few small cuts and doesn't know anyone who has been seriously injured by it.

"There's no rhyme or reason why it happens. It just goes 'bang' and goes everywhere."

And the mess is something Heveldt has to deal with today.

Luckily, his flat has another shower which they can use before the landlord can get someone round to fix it tomorrow when everyone is back on deck after the long weekend.