Poles, from which these buildings get their name, are natural shaped or round wooden timbers in diameter. The structural frame of a pole building is made of
tree trunks,
utility poles,
engineered lumber or
chemically pressure-treated squared timbers which may be buried in the ground or anchored to a
concrete slab. Generally the posts are evenly spaced apart except to allow for doors. Buried posts have the benefit of providing lateral stability so no braces are needed. Buried posts may be
driven into the ground or set in holes then filled with soil, crushed stone, or concrete. Pole buildings do not require walls but may be open
shelters, such as for farm animals or equipment or for use as picnic shelters. Enclosed pole buildings have exterior
curtain walls formed by girts fastened to the exterior of the posts at intervals about on center that carry the
siding and any interior load. The walls may be designed as a
shear wall to provide structural stability. Other girt systems include framing in between the posts rather than on the outer side of the posts. Siding materials for a pole building are most commonly rolled-rib
29-gauge enameled steel cut to length in widths attached using color-matched
screws with
rubber washers to seal the holes. However, any standard siding can be used, including
T1-11,
vinyl, lap siding, cedar and even
brick. Using sidings other than metal may require first installing sheathing, such as
plywood,
oriented strand board or boards. On two walls, usually the long walls, the
dimensional lumber girts at the top of the walls are doubled, one on the inside and one on the outside of the posts, and usually through-bolted with large
carriage bolts to support the
roof load. The roof structure is frequently a
truss roof supporting
purlins or
laths, or built using common
rafters. Wide buildings with common rafters need interior rows of posts. Sometimes rafters may be attached directly to the poles. The
roof pitch of pole buildings is usually low and the roof form is usually
gable or
lean-to.
Metal roofing is commonly used as the roofing and siding material on pole buildings. The floor may be soil, gravel,
concrete slab, or framed of wood. ==Modern developments==