Hardwood & Bamboo: HDF vs. Plywood Core
When shopping today’s engineered flooring, you have a choice between a HDF core (High Density Fiberboard) or a plywood core. While plywood is the more traditional core material and widely viewed as superior to HDF, the fact is that HDF is more stable, more resistant to moisture and considerably harder than the plywood used for engineered floors.
The species used in the construction of most plywood ranges from 500 (Poplar) to 1200 (Birch) on the Janka Hardness Scale, while the average Janka rating for HDF is 1700. The higher the core rating, the better the floor will resist unsightly dents and gouges caused by heels, falling dishes, and whatever else that might crash to the ground. Though it’s not the core that takes most of the abuse, it supports the layer that does.
One of the biggest reasons engineered hardwood flooring is chosen over a solid wood is its superior stability, or resistance to expansion/contraction with changing levels in humidity. Essentially, wood acts as a sponge absorbing moisture from the air, meaning the floor will shrink or swell dependent on the amount of moisture surrounding it.These changes usually occur from season to season and the rate at which this happens is directly correlated to the thickness of the material. While plywood is manufactured using very thin slices of wood laminated in a cross grain orientation, HDF is made by compressing tiny wood particles (recycled sawdust) with an eco-friendly resin. The result is a more stable core and one more well-suited for areas with large climatic swings or coastal regions where high humidity is more the rule than the exception.
A fear that most homeowners face is flood or other water damage. With exposure to water, HDF is initially more resistant to absorption. Plywood is more susceptible to absorption, and in either case the core material will swell. This is where plywood holds a slight advantage over HDF, due to the fact that you have about a 50% chance of the plywood returning to its original dimensions when dry. However, no floor performs well in a flood and, in the event of flooding, will likely need to be replaced. This is something that is usually covered by homeowner’s insurance and shouldn’t play too heavily in your overall decision.