Post and Beam or Braced Framing (1620 – 1830)
This method of framing was prevalent from our countries inception until about 1830. This period occurred before the Industrial Revolution, which allowed the mass manufacturing of building materials. The 1600 and 1700’s were typified with artisans bringing their trade from Europe. Craftsmen who hand hew their materials. A post and beam constructed structure was labor intensive, when labor was cheap, and required that most building materials be made onsite. This technique used heavy vertical posts (uprights) and beams (horizontal members). Posts were in the corners and along the walls, and were spaced at wide intervals. Beams were set on the foundation as a sill and used as “girts”.

 

The very wide spaces between posts and beams were filled with studs and floor joists. The usual spacing was 24”s on center. Sheathing and flooring were nailed to these studs and flooring. The main fastening methods of the time were hand made mortises (holes) and tenons (pins) or joints that fit together to hold the structure, hand made interlocking dovetail joints, or wooden pegs that originally were called treenails but their name eventually evolved into trunnels. At this point, iron nails were handmade. Mass production techniques did not exist. In fact, iron nails were so valuable at the time, that laws were created to prevent a homeowner from burning his house down so he could reclaim the iron products used in the houses construction, for there eventual use in a future home.

Again this method of construction was very labor intensive and relied on skilled craftsmen and large work forces who hand made their materials, flooring, sheathing and framing, and cut and formed their joints and nails. This system of construction relied solely on the large old growth trees/lumber that was present on the new continent. These methods would be greatly stressed with the reduction of the materials needed for construction with the passage of time.

Light Wood or Balloon Framing 1830 to 1930
With the arrival of the Industrial Revolution in the early 1800’s, the first mass-produced machine made nails were made at water-powered factories. These inventions were to revolutionize the building industry with the ability to produce more products for less cost. These events and the coinciding demise of the old growth timber forests in the East, along with the trained eye of George Washington Snow, an engineer from Chicago, would transform Post and Beam construction into the first genuine American building system called “Balloon” or light wood framing. This system utilized only the 2” interior stud portions of Post and Beam, which were deemed sufficient by Snow who made them into a standardized lumber (the 2”x4”, and 2”x6”). This method received the nickname “balloon” framing when old time craftsmen observed the framing and said it wasn’t stronger than a balloon.

Snow’s idea was to replace the heavy posts and beams with evenly spaced, standardized framing members spaced 16”s apart. The studs, or vertical framing members, were to run two stories from the sill to the roof. The floors were to be hung from the vertical wall framing. In 1865 it was quoted that a man and a boy could erect a structure that once took twenty men to frame. Balloon framing would cut building costs by 40 percent. How 16”s was decided upon for the framing spacing is not known.

Platform Framing 1930 to Today
In the 1930s, a method called Platform Framing was invented and is still in use today. Just like the change from Post and Beam to Balloon Framing, this new method would cut labor and material costs significantly, by using shorter easier-to-handle lumber for its framing, and its platforms provided a more convenient surface to work from. This framing gets its name because each story of the house is constructed on a separate platform.

It starts with the sill plate which sits on the top of the foundation. The first floor joists sit on the sill and floorboards are placed on top of the joists to create a floor or platform. When the floor is complete, the walls are constructed. The carpenter can then assemble the framing members of the wall directly on to the platform floor, following a blueprint. A sill plate, vertical studs, spaced 16”s apart and a double top plate. Window and door openings are predetermined, and are framed as a portion of the wall that is being assembled. The wall is sheathed and raised into position and then secured and braced by nailing through the sole plate into the floor and joists below. Each subsequent interior and exterior wall is assembled and added until the framing for the first floor is complete. Then the process is started over for the second floor.

The architect of the house laid out his design so that all “load” bearing walls are directly supported by the layer below. The weight of the second floor is conveyed to the first floor, and the first floor to the foundation, the foundation to the footing, and the footing to the soil. The load is constantly moving downward. An inspector should pay attention to design layout to insure that weight through load-bearing support is appropriate. Visual clues of structural issues can be: an uneven ridge line which is conveyed from framing problems or foundation settlement below, twisted or uneven siding, movement or displaced settlement cracks in the foundation, and displacement of doors and windows that don’t open or close properly.

Today, many man made framing methods and materials may be used in the construction of a house. A common building component found today is a truss. Trusses can be found in both floor support in the basement as well as rafter framing in the attic. A truss utilizes the principle of triangulation. A frame is composed of three end connected members (a triangle) which cannot change its shape. With a triangle as its base shape, a truss can extend further distances with less stress acting on it, and less vertical support. Trusses also allow a contractor to use less lumber, and labor, saving him approximately 1/3 over standard framing methods. The key to a truss is that it may not be altered in any way or it will lose its strength.



Other man made products used in building framing can be made of plywood glue laminates or lumber constructed into beams and timbers and used for floor joists or girders. Using thin sheets/veneers peeled from a tree or chips and bits the wood is glued together into a thin sheet. Then layers of thin sheets are oriented at 90 degree angles to provide strength. These framing materials are able to provide strength for less cost and can be designed and constructed to fit particular shaped building needs.

 

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