I mean this. Its not sealed at all in the inside, if it is. I cannot tell at all. The box itself is solid, just no caulk and I can tell it will leak air easily. However, with that being said what do you expect from great prices and fast shipping? Box is well designed imo for a simple 12 box. Carpet is fine as well. Just no Caulk which over time will cause leaks
The boxes are all glued together before we use brad nails on them to assemble. Not only is this done, but we also use a light layer of bondo on the outside before carpeting. Enjoy your box