You have asked two important questions about durability and safety in bamboo vs.hardwood.
Durability implies something that lasts a long time and will hold up to various climaticconditions as well as foot traffic.
- That requires consideration of the finish on the surface,in addition to the type of wood, glues, and moisture content as they affect the overallstructure of the floor.
- You must also understand the subfloor, whether concrete or wood,and know how it impacts the flooring that sits on top of it.
The issue is not what species it is, but how it's made and how it's installed. There are horror stories about both bamboo and hardwood floors that buckle and crack inhot dry climates, and these same complaints are often heard in very wet climates as well.
There's nothing inherent about hardwood that makes it better than bamboo. Local
hardwoods seem to work just as well as other domestic or imported hardwoods or
bamboo; as long as they're installed and acclimated correctly over a suitable subfloor.
Floating engineered floors work best
Our experience in hot or dry areas such as Arizona, Colorado or California is that floatingengineered floors seem to work best for both bamboo and hardwood.
Floating means that it is not glued or nailed down but sits on top of an 1/8" underlaymentalong with a vapor barrier. This allows the floor to expand and contract as needed over aconcrete or plywood subfloor uninhibited by nails or glue.
Engineered means that the floor has multiple layers of hard or soft wood, bamboo, high-density fiberboard (HDF) or some combinations of both. The purpose of multiple plysis additional strength and resistance to movement across the grain or with the grain ofthe wood.
- Excessive dryness or excessive moisture tends to exert pressure in variousdirections.
- If the wood is solid, for example, it tends to twist and turn according tothe grain of the wood. If it is engineered, the cross-plys keep the plank from twistingand turning so easily.
- We've seen engineered floors subjected to extreme moisture andextreme dryness causing minor buckling, but when the moisture levels change, the floorrelaxes back into its original shape. This does not happen as quickly or easily with solidwood floors.
Our favorite engineered hardwood floor is made by a Swedish company called Kahrs,which invented floating floors some 25 to 30 years ago.
In Sweden, many people useradiant heat under their floors, and Kahrs designed its floors to accommodate infraredheat. Kahrs allowed for the natural contraction process by using quarter sawn wood, which is more stable than plain sliced wood in-between the top and bottom layers.Instead of one solid core of quarter-sawn wood, its broken into small fingers andseparated with tiny gaps. As a result, the wood expands and contracts inside and not onthe surface.
Kahrs, as well as other manufacturers such as EcoTimber, US Floors and EcoFusion have also been successfulwith HDF cores due to their extreme stability.
However, there is much more to the storythan just the core structure. How an engineered floor is made is quite complex and involves many steps includingthe use of the right type of core material, drying and gluing the wood together in just theright sequence so that it maintains the right amount of moisture. If the surface is a densehardwood, for example, then the core of pine or HDF as well as the wood on the bottomplane must be able to move in harmony with the hardwood on the surface. This is not aseasy as it may seem.
All types of glues have been used to control moisture and overcomethe movement of each plane of the wood. Unfortunately, some of the adhesives used byhardwood and bamboo manufacturers are not safe. To their credit, the Europeans seem to be bent on non-toxicity of their adhesives and theirfinishes. As a result, their products are safer than anywhere else. This applies to cork,Marmoleum, hardwoods, softwoods etc.
The latest trend in hardwood flooring coming from Europe is oiled finishes. These old-time proven finishes are not only non-toxic, but they tend to allow the floor to breatheeasier, which means it can naturally adjust to the changes in climate.
We're now seeingthese on both bamboo and hardwoods.
Most flooring today has a finish prepared with aluminum oxide or polyurethane, both ofwhich are petroleum-based topical sealers that perform very well at resisting abrasion andmoisture, but are expensive to apply and reapply years later. They also have an unnaturalplastic look and feel.
Oiled floors, on the other hand, are much more reparable, and canbe reapplied easily and cheaply without professional experience. Oiled floors patinanicely over time, which tends to enhance the color and feeling of the wood/bamboosurface.
If you have further questions, or need specific answers to brands, please feel free to emailme.
Joel Hirshberg, President
Green Building Supply
For more information:
Read "Can bamboo flooring work in very dry, desert-like environments?" a Q&A answered by Bill Bradbury.