Hey Walt. It's 9x9. Sounds like a lot people cut the hole bigger to allow for a standard size, and that would mean I could add a fan. I don't know...Probably the right thing to do but I might just stick with the 9x9. Not sure.
I need to stop spending money on this thing for a little while, but I also want to do things "right". The previous owner said that this vent leaks
a little in major downpours. So I want replace it, because looking at it, I think it's more likely that it's leaking because of the cracked corner of the lid than because of needing a resealing. So I don't think that resealing it would be any kind of "bandaid" fix. I think the only way to stop the leak is replacing it.
But another $150 or so on a powered fan vent, plus taking the sawsall to my roof, just doesn't sound great right now...