Chapter 2 - Floor Systems

Why would you use a double Sill Plate?

To elevate the ceiling height in the basement and bring the height closer to to 96", however 12" anchor bolts must be used with a minimum of 7" of embedment in the foundation.

What are the two most common footings used for wood frame buildings?

1. Spread Footing / Foundation 2. Pier Foundation

5. Floor Joist

Lay the floor joist on the marks created on the sill plate. Nail to the sill plate.

2. Sill Sealer

Roll out sill sealer on the foundation and press the bolts through the sealer.

What is the process of building a floor system?

1. Layout 2. Sill Sealer 3. Sill Plate 4. Rim Board 5. Floor Joist 6. Sub-Floor Adhesive 7. Sub-Floor or Sheathing

What are the three framing types used in construction?

1. Post and Beam / Timber Framing 2. Ballon Framing 3. Platform Framing

What are the Anchor Bolt Codes?

- Anchor bolts must have a minimum of 7" of embedment. - Anchor bolts must be no further than 12" from the end of a sill plate. - There must be a minimum of 2 anchor bolts in any single piece of sill plate. - Areas with seismic activity require square bearing plates to be installed under the nut and washer to keep bolts from being pulled through the plate.

What is a Girder?

A member which supports repetitive members like floor joists. In a wood floor systems, a girder will support joist with a post contacting a pier or spot footing to transfer the loads to the earth. Girders cannot bear directly on concrete but must be protected from mold, fungus, and rot. Frequently a beam pocket is cast into a foundation, the perch which the beam rests on must have treated lumber or galvanized metal between the concrete and beam.

6. Sub-Floor Adhesive

After all the joist are installed a bead of sub-floor adhesive is placed on top of each joist. Only add glue to a small area, typically the top of the joist which one sheet will cover.

What is a Pier Foundation?

Also called Spot Footings, it is designed to carry a point load from a post or column.

What is a Spread Footing / Foundation?

Also called a "T" foundation because of the shape they form when cast. The load carried by this foundation is distributed along the length of the foundation and spread out.

What is Subfloor Adhesive?

Glue which adheres the subfloor sheathing to the floor joists. This improves the performance of the floor system as a shear resisting system. The adhesive is applied to the top of the joist and the sheathing is applied on top the adhesive and joist. The two different tube sizes are quarts and pints. Quarts is more cost effective.

4. Rim Board

Install the rim board around the perimeter of the floor system on top of the sill plate. Make sure the rim board is flush the outside of the sill plate.

3. Sill Plate

Install the sill plate on the layout line you snapped.

What is a Sill Plate?

It is placed on the foundation over the sill sealer and is help in place by anchor bolts and bearing plates. The sill plate is manufactured in even 2' lengths and 16' length pieces being the most common used in production. The wood must be treated or of a species that will resist decay from moisture and fungus. Sill plates must be treated limber, redwood, cedar, or cypress. The least expensive option is treated lumber.

What is a Floor Joist?

Members which span between bearing points and support the live load (LL) of the building like people and furniture, and dead load (DL) which is the weight of the materials that make up the floor system.

What is Subfloor?

Plywood or OSB is sheeting or sheathing that is placed over the joists. The connection of this sheathing is very important to the integrity of the floor system. Typically, the sheeting is fastened with subfloor adhesive and nails (8d ring shank) or screws.

7. Sub-Floor or Sheathing

Start in one corner of the floor and install the sub-floor and install the sub-floor or sheathing with the tongue pointed to the outside of the floor system. The groove must be available to connect the next sheet. Nail as directed on specification in the engineering. Space between butt joints of sub-floor with 8d nail. Leave 1/8" gap for expansion if the floor were to get wet and the material expands.

What is a footing?

Supports the foundation of the building and is placed on undisturbed native soil or compact engineer fill dirt. Footings must be placed at a depth where water will not be able to freeze under the footing. Cold regions have minimum depth requirements from finish grade to bottom of footing.

What is Ballon Framing?

The bearing stud is placed directly on the sill plate and the joists are slid in-between the studs. The walls continue to the top of the structure and bear the rafters for the roof.

What is Post and Beam / Timber Framing?

The earliest form of structural wood construction. The joints were joined using a Mortis and Tenon joint or connection. These joints used wood pegs to lock the timber joints in place, Much like we use nails today. These members were heavy and could span large distances. It is still used today in Ski loges and rustic style buildings.

What is Platform Framing?

The walls sit on top of each floor system constructed. This framing type speeds up the process.

What is an Anchor Bolt / J-Bolt?

This is what secures the building to the foundation. They are embedded into the concrete foundation when the concrete is poured and before the concrete hardens. The bolts hook around the rebar located in the foundation.

1. Layout

Use a chalkline and snap lines where the plate will be placed. Make marks for each floor joist and subtract 1/2 the thickness for the first joist than use your selected spacing from allowable span charts.

What is a Framed Opening?

Used to gain access into a crawl space or used as a chase way to allow the installation of mechanical equipment.

What is a Draft Stop / Fire Stop Blocking?

Used to reduce the spread fire. It is placed over middle bearing points and in a normal fire requires about an hour to burn through.

What is Sill Sealer?

Used to stop wind penetration into the building. It is a foam placed under the sill plate prior to installing the sill plate. It forms around the uneven surface of the foundation and sill plate and adds a seal against the environments and potential infestation from insects. It is manufactured in 50' rolls.

What is a Column / Post?

Used to support a point load which is transferred from other members. Columns or posts typically hold headers or girders.