velux vertical elements

Griffner Coillte use them. They specialise in timber frame homes that are build offsite and assembled on site. They are not like traditional timber framed houses with a brick/concrete outer leaf and timber inner leaf. The griffner coillte system is all timber, and so water proofing is a main concern. If they use the verticle/corner windows I would say they are safe.

And besides as long as you go to Velux and not some cheap copy, you are safe. I’ve never heard their standard called into question before.