It's designed for twin mattresses up to eight inches tall (we recommend splurging on the luxury six-inch Saatva Bunk & Trundle mattress), and has a low loft that's great for preserving overhead space.

A top bunk should have guardrails that measure at least five inches from the top of the mattress and continue all around the bed. There also should not be any gaps in the guardrails large enough ...

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