Most people take wood for granted but structural engineers know better. Of all the natural
building materials, wood is the most versatile and it rivals many of the highly engineered
products of modern era. Like steel, but unlike any other natural material, wood is as strong in
compression as it is in tension which means that it can be used for both columns and beams. It
is also ductile which means that can bend a great deal before breaking, making catastrophic
failures without warning unlikely. It is easily cut with even basic tools, and can be carved and
shaped. In many climates, a variety of wood is readily available and trees are easily felled and
Wood has three major disadvantages. Wood shrinks as it dries out and swells as it absorbs
moisture which means that a wood building will tend to pull apart at its joints. Wood is also
attacked by insects, although some woods are far less susceptible to this than others. Finally,
would burns and wood buildings can be quickly destroyed by fires.
William Penn, who would have been 22 at the time of the great London fire of 1666, was
determined that his green country town of Philadelphia would not experience a similar fate.
Penn started a brickyard in 1683 and later regulations required residents to have buckets and
ladders to fight fires, but claims that Penn or other officials actually banned wood construction
seem to be unverifiable.
The first buildings built in area were log cabins, first by the Swedes and then by the first English
settlers in the 1680's. Wood houses continued to be common in the countryside but by the early
1700's visitors commented that most houses in Philadelphia were made of brick. Wood
construction could be found in Philadelphia throughout most of its history, particularly in the so
called river wards along the Delaware outside of the old Penn defined city, as numerous
historical photographs show. Few colonial era wood buildings have survived due to decay and
fire, not because they never existed.
Swedish Cabin, Upper Darby