Depends on how they're set in the frame. If we're not seeing any doors, then it could mean they're sealed in such a way that would prevent weight of the sand from forcing them open...

[He turns around, rubbing his chin in thought.]

Maybe the ladder is a red herring...maybe there's a switch or something that opens a door. One obfuscated by the panic from the situation and the sand pouring down...

We should check the walls.

[He moves and dislodges his feet from the sand in large, sweeping steps then stops as a thought occurs to him. Back still facing her, he drops to a knee.]

Hop on my back.