Our floor boards are 28m thick single tongue and groove with expansion gaps on the underside.
A thicker floor is sturdier and will hold more weight, important if you have furniture or other heavy items inside. There is less bounce as you walk across it compared to thinner floors.
The tongue and groove design helps the floor boards to fit together securely.
The expansion gaps on the back of the floor boards are very important. All the wood in your log cabin will expand and shrink in the different seasons and temperatures, this is perfectly natural.