Anyone experienced this before?! 

 

I bought double glazed skylights from a local supplier and installed them myself around Xmas time. They rest on a standard timber upstand, are not screwed in place but do have two continuous beads of mastic around the top of the upstand. 

 

This morning I discovered that the inner glazing panel of one of the skylights had shattered. The outer panel is fine, which rules out impact from outside, and nobody was in the building yesterday, ruling out impact from below. 

 

On Saturday I used a hole cutter to create a vent in a vertical surface about three metres away from the skylight in question. That might have sent a vibration through the roof structure and cracked the glass perhaps. 

 

Timber does of course expand and contract, but timber upstands are standard practice and mine are perfectly ordinary. 

 

Any ideas on how I can go about replacing the unit? If I have to force it up and off I'm concerned I will damage the upstand. 

If it was a Velux one, they had problems and were replacing them.