1. Floor Joists
4/11/10

2. What is a joist? There are many different types of joists.
All joists are normally load bearing.
All joists typically run in the same direction.
Today we are covering Floor joists.

3. Floor joists

4. So to recap: Foundation wall has been poured Sill plate is attached
Now time for floor joists
What type?????

5. Floor joist
Floor Joists carry the Structural load of the houses contents.
Examples
Interior walls
Carpet
You
Grand piano
One normally does not think about how much weight can my floor hold but the truth is it is a very important factor in planning a house.

8. Types of load
Dead Load: Total weight of the building, includes anything permanently attached
If its glued, nailed, or painted on it counts.
Live Load: Weight not permanently attached.
Table
Chairs
You

10. Joists Spans
Joists are commonly spaced at intervals of 16” on center……..
However depending on load they may be spaced less or more.
16,24,14,12 are sometimes more common.

11. Back to the foundation……
Joists very rarely span the length of a house.
Typically they run a little over half the width then rest on a beam of some type then another joist continues on to the other side of the house.
This “beam” is commonly referred to as a girder.

12. The Girder A girder will always run perpendicular to the joists.
Girders are typically supported in two ways.
Pocket in the foundation wall
Posts

16. The Girder Cont.
The girder carrys the nearly the entire load of the structure.
MUST BE STRONG!!
Can be made out of many different materials.
Wood
Metal
Composite wood. (Human made) AKA Engineered.

17. Girder Floats
No not in water……..well maybe…..but not what I am talking about.
Floating is a term commonly used to refer to any part of the house that is not permanently attached it only held in place by other parts or its own weight.
So therefore the Girder is only held in place by its own weight, the beam pocket, and THE WEIGHT OF THE WHOLE HOUSE!

25. Built Up Beams Are typically made of 2x10 or 2x12
Are nailed in a particular pattern
Number of boards needed is determined by load carried. Typically 3-4 is all that is needed.

26. Posts Posts can be located in both basements and crawl spaces
Help carry/distribute the weight of the girder.
MUST HAVE APPROPRIATE FOOTINGS!!!!!!
Foundation rule applies.
2x the size of the posts. Min.

27. Post Materials Post are typically metal and adjustable.
However wood and masonry are sometimes found in house.

29. How joists are laid out
Typically no attachment made to the Girder. “ It FLOATS on the girder”
The joist itself rests on the sill plate. And is sometimes toe nailed to be held in place.
Toe nailing: one or two nails placed typically on an angle, not meant to hold it permanently just temporarily.

30. Rim joist
Rim joist sits on the sill plate and runs perpendicular to the joists.
Normally nailed and attached permanently to the floor joists.

35. Assignment
Add to your basement drawing parts that you learned about today
Girder, Posts, Joists, Rim Joist
Be sure to have Emergency openings, windows or vents.
Specify Wall types too. Masonry, Wood….ect.