Monday, December 10, 2012

A greenhouse skylight repair...

The first big storm of the season always brings with it the liklihood of a few leaks in the greenhouse.
The ravine was rushing with rain runoff.

These skylight panels are laminated triple glazed. They're heavy.
They're held in place by the combination of a bead of sticky butyl glazing tape (between the panel glass and the aluminum channel the panels are bedded in) and the compression of rubber-lined batten strips which are screwed into the aluminum channel between panels. 
As solar energy waxes and wanes throughout the year, the expansion and contraction of dissimilar materials brings gravity into play, the sticky glazing bead loses its bond, and the screws loosen up. Slowly the panels begin to sag and a gap develops along the top edge where they slip out from under the top batten.

After mopping up the marble floor and wood window sills inside, I attempt (successfully, it turned out) a temporary repair with a roll of aluminum flashing, seen above.
 The far panel has slipped down about 3 or 4 inches.

I waited for better weather to tackle a more permanent solution.

Scaffold plank in place and batten strips removed, I began pulling up each panel and repositioning it on new glazing tape after cleaning both sides of the panel and the aluminum bed where the tape adheres.

An earlier 'expedient' repair last year with roofer's leakstop tape, visible in the photo above, has given way to gravity.

The aluminum channel at the bottom is cleaned and siliconed into place, held with duct tape until the silicone cures. The batten strips are re-fastened and screwed down as tightly as possible. Stainless steel screws into aluminum channel means threads easily stripped out the softer aluminum.
The south facing slope and the stone parapet make for a lot of heat. That's my theory of why this particular roof section has needed this kind of attention repeatedly.