I-joists are the most common way to structurally frame an upper floor in a residential building. I-joists are also commonly used in flat roofs for both residential and commercial buildings. At Donaldson Timber Engineering, we design and cut all of our I-joist flooring systems using MetsaWood's Finnjoists.

Finnjoists are manufactured using OSB for the webs and Kerto LVL for the flange material. This results in an I-Joist that is lightweight, incredibly strong and dimensionally stable.