As with most wood products that live outside, exterior trusses, porches, and ‘trimber’ will require a little maintenance every few years to keep them looking great. When we first install exterior (or interior) timber it is coated with an oil based finish. Over time, exposure to the elements, air pollution, natural pollens, dust, and more wear the oil away and tints the wood a grey or pale beige tone. In some locations this can take five years; in others, two years; still in others a year or less. In our case we went a little over four years before cleaning and re-finishing the timber frame porches that are the main entrances to our Farmington, New York office.