Solid Strand Bamboo flooring will shrink just like a hardwood floor when indoor relative humidity drops below 35 percent during the heating season. Bamboo flooring manufacturers recommend maintaining humidity over 35% through the heating season. To increase indoor humidity a whole house humidifier is recommended— steam humidifiers tend to perform best.
When bamboo flooring is installed floating method the shrinkage is more prominent because the planks are connected to each other and the floor shrinks as a whole. Overall shrinkage may result in gaps along the walls, through doorways, at kitchen islands, or any object that stops the floor from moving.
Transition strips should be installed at doorways, and proper expansion space in the width and length direction must be provided. Your installer has to make sure nothing will stop the bamboo planks from contracting and expanding as one unit.
Without proper humidity levels, a 5.25” bamboo plank installed floating method in a 15’ room will shrink on average 1/64” per plank. The total shrinkage across the 15′ room equals 34/64”.
On occasion, solid strand bamboo floors shrink excessively and wider than normal gaps occur. When this happens the floor should be evaluated by a Certified Bamboo Flooring Inspector.