Generally speaking, rigid plank does not require expansion space, as it expands and contracts very minimally. That said, we do recommend the industry accepted 1/4" as a good standard practice. While your floor may not expand or contract, the house itself can. In reality, it takes a combination of both extreme temperature fluctuations and a very large room for this space to become necessary (the larger the room, the more small shifts can add up). If you plan to install baseboards or quarter-round anyway, this 1/4" will be easily covered.