Very nice little birdhouse. Do you get Swallows or Bluebirds around your area? If you do strongly consider using the smaller hole size for your birdhouse so that Swallows and Bluebirds will nest but sparrows can't get in. When I recently had to deal with flocks of house sparrows going to my feeders I did a lot of research on them so I can get rid of them. They just became too much.
House sparrows are an invasive species to North America that just keep growing. And they are right bastards. They invade swallow, bluebirds and other nests and will destroy eggs and kill young ones. In fact they are a big factor in the declining bluebird population.
Because they are not protected by the Migratory Act there are people and organisations that kill them by the hundreds and destroy their nests to help control the population. I could never do that myself but understand why its needed.
Anyways just a thought. I worked hard myself adjusting feed and feeders for the past two years to get rid of grackles, red-wing blackbirds and now house sparrows. Now I mostly get just the native species. And I'm not refilling the feeders every day anymore.