replying to daisy, Iggy wrote:
Yep, you'll want to seal everything, look into Radon Seal (
https://www.radonseal.com/ ) it's the far and away best, because it's permanent.
Although, in a horizontal situation the joints between different materials will
eventually open and need caulking. But yes, those types of Construction Bricks
are intended for exterior use and should do very well for a good long time.