February Meeting

The February meeting was canceled because of inclement weather and held on March 4 at the Johnson Creek Fire Dept.

The meeting was called to order at 7:00 PM and Jamie Gould of Johnson Creek gave an informative presentation on construction techniques and materials.

He highlighted the two types of construction popular in the US during the past century. Which are primarily the bulk of all homes you will find in our fire districts. The first is Balloon framing, which is the method of wood construction used in the United States up until the mid-1950s (pictured to the left). It utilizes long continuous framing members (studs) that run from sill plate to eave line with intermediate floor structures nailed to them. Once popular when long lumber was plentiful, balloon framing has been largely replaced by platform framing.

Because the framing members are continuous, there are no fire breaks. If you respond to a home that looks like it was made before 1960, assume it is balloon type framing and plan your attack accordingly.

Today, in Canada and the United States, the most common method of light-frame construction for houses and small apartment buildings as well as some small commercial buildings is Platform framing.

From Wikipedia, the framed structure sits atop a concrete (most common) or treated wood foundation. A sill plate is anchored, usually with 'J' bolts to the foundation wall. Generally these plates must be pressure treated to keep from rotting. The bottom of the sill plate is raised a minimum 6 inches (150 mm) above the finished grade by the foundation. This again is to prevent the sill-plate from rotting as well as providing a termite barrier.

The floors, walls and roof of a framed structure are created by assembling (using nails) consistently sized framing elements of dimensional lumber (2×4, 2×6, etc.) at regular spacings (12″, 16″, and 24″ on center), forming stud-bays (wall) or joist-bays (floor). The floors, walls and roof are typically made torsionally stable with the installation of a plywood or composite wood “skin” referred to as sheathing. Sheathing has very specific nailing requirements (such as size and spacing); these measures allow a known amount of shear force to be resisted by the element. Spacing the framing members properly allows them to align with the edges of standard sheathing. In the past, tongue and groove planks installed diagonally were used as sheathing. Occasionally, wooden or galvanized steel braces are used instead of sheathing. There are also engineered wood panels made for shear and bracing.

The floor, or the platform of the name, is made up of joists (usually 2x6, 2×8, 2×10 or 2×12, depending on the span) that sit on supporting walls, beams or girders. The floor joists are spaced at (12″, 16″, and 24″ on center) and covered with a plywood subfloor. In the past, 1x planks set at 45-degrees to the joists were used for the subfloor.

Where the design calls for a framed floor, the resulting platform is where the framer will construct and stand that floor’s walls (interior and exterior load bearing walls and space-dividing, non-load bearing “partitions”). Additional framed floors and their walls may then be erected to a general maximum of four in wood framed construction. There will be no framed floor in the case of a single-level structure with a concrete floor known as a “slab on grade”.

Stairs between floors are framed by installing stepped “stringers” and then placing the horizontal “treads” and vertical “risers”.

A framed roof is an assembly of rafters and wall-ties supported by the top story’s walls. Prefabricated and site-built trussed rafters are also used along with the more common stick framing method. “Trusses” are engineered to redistribute tension away from wall-tie members and the ceiling members. The roof members are covered with sheathing or strapping to form the roof deck for the finish roofing material.

Floor joists can be engineered lumber (trussed, I-beam, etc.), conserving resources with increased rigidity and value. They allow access for runs of plumbing, HVAC, etc. and some forms are pre-manufactured.

From a firefighting standpoint, platform framing provides good fire stops, but some of the engineered lumber presents hazards. Jamie touched on the wood I-Beams as a specific risk.

Recently Milwaukee's WISN Channel 12 did a report on the hazards to firefighters when dealing with platform construction made using wood I-beams. Take a moment to read the article and watch the video.

Jamie brought in some awesome wall mock ups, truss models, and samples for members to take back to their departments.

Departments in attendance: Jefferson, Cambridge, Whitewater, Ixonia, Helenville, Lake Mills, Johnson Creek, and Rome.

Hosting the next meeting: Lake Mills Fire Department