After the heat of the day - we get this lound cracking noise that seems emanate from our windows which are Pella casement over 2 wide awning 70 x59 with 1 fixed awning
35 x 25 and same size which opens - we have opened the wall and worked to isolate
any framing problems- still have this recurring situation
Any ideas? Windows are wood inside aluminum cladding outside

You need to contact Pella and have one of their guys come check each unit. It may just be thermal expansion and contraction. Where are you and have you painted the window's exterior?

Hi, I am a building contractor. I get this cracking probably once a week. Just had it 15 minutes ago. Sounds mostly like a bird hitting the glass. Last week it happened at 4:30 a.m. I moved in to my house last fall, Sept 2012. I have called Pella but no answer yet. Good Luck. Pat