Light port prototype – close-up. (B) points to the port’s basic framing, which is largely unseen behind the green sheathing board. This framing bears the weight of the glass block and positions it in the wall. It’s a little hard to see that it is a different piece of wood, but (A) points to the “window stop” – a frame of wood which reduces the opening a bit such that it captures the window behind it. There would be a corresponding stop behind the glass.
I used scraps of plywood for the stops in this mock-up. Solid wood is more likely for the real thing.
A glass block installed from behind, pushed up against the front stops. The red overlay is approximately where flashing tape would be applied if this were a real build. It was drawn on the image roughly to suggest what would be done, don’t judge the layout/coverage 😀.
The flashing tape will prevent water ingress along the perimeter of the stop where it abuts the green board. A bead of clear silicone caulk will be applied to the glass/stop interface, as well, making this assembly weather-worthy from the outside.
A very rough mock-up of how the whole light port will look installed in the exterior wall. I used scraps to make the window dressing and simulate some of the siding — these are NOT the real boards or siding style — but what they do provide is a sense of how the light port will appear on the exterior of the house and how it interfaces with the siding. The interior will actually look much the same, with the block recessed slightly.
One thing I forgot to do on this prototype was to slope the bottom stop and trim to shed rainwater. Even when sealed up weather-tight, the trim will suffer if water is left standing on it repeatedly. I’ve made that mistake before. It’s the difference between 5 years of durability and 20. The red triangle annotation shows the approximate slope which would be applied.