I was at a friend’s house yesterday and got a chance to look at some dislodged windows that seem to be from a lightning strike but am unsure? 1960s tri-level house, cedar siding, new vinyl windows installed 4/5 years ago. About two months ago the house was hit by lightning and most of the damage occurred through the co-ax cable lines - fried his TVs and A/V equipment and scorched some cable jacks. No noticeable impact to the electrical system.
Anyway, after the strike he noticed many of his windows have moved outward… some as much as 1/2". The strange thing is there’s no sign of any movement from inside. The damage is definitely worse on the windows closest to the strike and tapers off from there to roughly half way around the house in each direction.
He was home at the time of the strike and didn’t feel any great pressure change in the house but admits it was fast, loud and jarring so anything is possible.
Anyone ever seen this? I told him the next step is probably to pull the trim and look at the nailing fins and other visible parts. I’m still trying to wrap my head around how the windows can move outward 1/2" on the outside but show no signs inside.
This is more what I was thinking as well. There are several aspects that might support that.
No apparent bowing of the windows or window trim itself.
Where the visible separation is the siding appears slightly bowed.
Looking at both the top and bottom separation points there appears to be a shear in the siding but it is to clean a shear line to be from stress. Possibly they were short pieces used to compensate for undercutting the siding? When the “compression from the” lightning strike occurred they were just separated at the sealant (caulk) point.
Definitely an oddball occurrence if it was from the lightning strike. Possibly it was a growing issue he never noticed before?
Blast wave from air expansion from the lightning strike produces the same type pressure wave as a dynamite blast. The initial blast wave applies pressure to the house facing the blast and in a fraction of a second the air rushes backwards towards the source of the blast. Windows flanges are designed to withstand wind pressure not suction pressure. The house I inspected a few years ago pull away from the wall due the suction phase from a gas explosion from a nearby building. Similar to your photos.
Looks like a framing problem. Where the first floor meets the second floor.
Weak framing could cause the siding next to the windows buckle.
Even the siding orientation is poorly worked out. The first and second image or the lap reveals this hypotheses.
@mfellman - Curious side topic…Did your buddy have a surge suppressor installed on the Main or Sub Panel, and if so, did it help? I know they are required for new, but most of the PNW never gets much lightning, and so I often wonder if they actually help/work with a strike to the home.
He’s pretty on top of things… windows were only put in a few years ago. Of course, anything is possible but the pattern of damage and proximity to the strike sure seems to points towards some relationship.
No whole-house surge protection… I’m not sure about cable system grounding. Standard in the area is to run (small) wiring to a metallic hose bib in some hope it makes a path to the earth. I’m pretty sure my buddy’s house still has the metallic water supply. I’ve often wondered how well those little (14?, 16? gauge) wires would do. This strike was pretty odd as his house isn’t near the top of a hill at all. A nearby tree looks to have received the worst of it but some hit the house as well.
