Glencoe: Section 65 Flashcards
Select floor joist lumber carefully so that the floor will be,
flat and strong
Any joist with a slight edgewise bow should always be placed with the crown
on top
Crown:
the outermost curve of the bow.
How do you mark a joist with a crown:
an arrow pointing to the crown.
What happens to a crowned joist when the subfloor and loads are placed on it?
straightens out.
Be sure that knots in the joist are on its X side
compression (top) side. because they are less likely to cause failure in this location.
Why is a large knot on the tension side of the joist bad?
it can be pulled apart. A knot at the top will be compressed
Alternative layout method to marking joist location on the sill plate?
marking the top of the rim joist
The specific installation details for I-joists vary X. Always read the instructions for the specific I-joist you plan to use.
according to the product’s manufacturer
When installing an I-joist, check the X, do not check the Y
check the span table for that product, do not check the span tables for lumber joists.
The layout difference between I joists and lumber joists?
I-joists are usually not overlapped because they are available in long lengths
Do not assume the span listed for one line of engineered lumber products
will be the same as the span for another line.
Intermediate bearings:
load bearing wall must stack over X
X may be required at shear walls above or below.
wall below
Blocking panels
Temporary braces for joists (X maximum) at Y’ OC fastened at each joist with a Z nails minimum
1x4
6
2-8d (2 1/2”)
Bearing plate to be flush with
inside face of wall or beam
I joists are nearly always supported by
metal joist hangers.
The width of the hanger that supports the I-joist should match the width of
the I-joist
A backing block prevents
an I joist from moving within the joist hanger by improving its fit
Where an I-joist runs continuously over a support (a girder for example)
web stiffeners should be nailed to both sides of the web to improve the load-bearing ability of the i-joist. The stiffeners also provide addition bearing surface for lumber or I-joist blocking
Depending on the dimension of the I-joist, web stiffeners may be made of X”, Y”, or Z” thick plywood or OSB rated sheathing.
1/2”, 5/8” or 1”
I joists with usually wide flanges may even require a web stiffener made from nominal X” lumber.
2”
Why are stiffeners 1/8” shorter than the exposed potion of the the web?
so they do not force the upper flange out of position.
Installing lumber joists:
Step 1:
X, using 16d nails every Y” OC
Be sure that the outside face of the joists is in the same plane as the outside edge of the sill plate.
Toenail the rim joists to the sill plates
16”
Installing lumber joists:
Step 2:
X
Add extra joists or leave out the joists where large openings will be located.
Place the joists over the layout marks, laying them flat for now.
Installing lumber joists: Step 3: Tip the outermost joist up on edge and align one end with the end of a rim joist. X Y
Nail through the rim joist and into this joist with two 16d nails
Toenail this joist to the plate with 16d nails spaced 16” OC.
Installing lumber joists:
Step 4:
Proceeding from one end of the house to the other, X. This process is sometimes called Y.
Nail through the rim joist and into each floor joist with X . Toenail each joist to the sill plate with X
tip each joist on edge, crown up, and align it with the layout marks
rolling the joists
two 16d nails
three 8d nails.
Installing lumber joists:
Step 5:
toenail each joist to the girder with 8d nails
Installing lumber joists:
Step 6:
Face-nail overlapping joists to each other with at least three 10d nails.
Another method for installing web stiffeners is using X
10d clinched nails
Clinched nail:
a nail of any size or type whose point has been bent over with a hammer where it exits the wood. Which prevents the nail from pulling out
Where solid-wood blocking would be required on a solid-wood joist system, similar blocking may be required for
an I-joist floor. Short lengths of I-joist stock may be used instead of solid lumber.
Where I-joist blocks intersect I-joists,
a backing block or web-stiffener may be required.
A solid wood rim joist with an I joist floor is
A solid wood rim joist is not suitable for use with an I-joist floor
What type of rim board is used with an I-joist floor?
an engineered product such as LVL is used, called a Rim board
Rim board:
a rim board ties the ends of the I-joists together.
Dimensions of Rim board:
up to 24’ in length and 1 1/8” in thickness. Same depth as I-joists
Pros of rim board
does not shrink as much as lumber
To install a rimboard:
Toenail it to the sill plate with 8d common or box nails space 6” OC or as recommended by manufacturer.
When nailing through the rim board and into an I-joist,
make sure one common or box nail penetrates the center of each flange.
Notch:
a saw cut made in the end or edge of lumber.
Why does building code restrict notching
careless drilling or notching reduces strength of a joist
Notches may not be located
in the middle third of a joist span
The location and size of notches permitted in a solid wood floor joist are based partly on the
depth of the floor joist
Drilled holes must be at least X” away from the top and bottom of a joist
2”
Flanges must never
be cut drilled or notched.
I-joist contain what for utility access?
pre scored holes to be tapped out with a hammer.
If more holes or bigger holes are needed in an I-joist
consult the manufacturers literature.
When nailing through the rim joist or rim board and into the ends of a joist, always place
the bottom nail first. This holds the two pieces together so you can move your hand out of harm’s way as you fire the upper nail into place. Don’t forget to wear eye protection
Bridging:
a method of bracing between joists. It is done to distribute loads, prevent the joists from twisting and add stability and stiffness.
Two types of bridging:
solid bridging
cross bridging
Solid bridging:
solid bridging is made of solid lumber that is the same dimension as the joists. Offset or staggering the blocks allows them to be end nailed through into the joists perpendicular in between
Cross bridging:
(diagonal bridging) is more common because it is very effective and requires less material. Two bridges are used in between each joist in an X shape.
What type of lumber is used in cross bridging:
What other material can be used
1x3 or 2x2
metal-strap cross bridging
before installing bridging, snap a chalk line across the
tops of the joists as a guide.
When installing solid-wood cross bridging, leave
the bottom ends loose until the subfloor has been laid.
Why should you leave the bottom ends of solid-wood cross bridging loose until the subfloor has been laid
because the joists are then allowed to adjust themselves into the final position, then you complete the nailing
Bridging is not generally required by code unless the joist exceed
2x12 in depth.
Why would you bridge joists even though it is not required by code?
Because it is a cost effective and efficient way to stiffen floor.
If joist is over 8’ long and you want to install bridging, where do you install it?
at the center
If joist is over 16’ long and you want to install bridging, where do you install it?
install two rows of brides equally spaced on the joist span
Framing under bearing walls
joists should be what under each load bearing wall that is parallel to the joist
doubled under each load-bearing wall that is parallel to the joists.
Bearing wall
a wall that supports a load in addition to its own weight
if a wall will contain plumbing pipes or heating ducts, what can be added to the joists
blocking.
What dimensions are the blocking that fit under load bearing walls containing pipes or vents
the same size stock as the floor joists
blocking in doubled joists should be spaced no more than
4’ OC
It is often necessary to create large openings in the framing system to accommodate stairwells and chimneys. In these cases, the joists framing the opening
should be doubled and the interrupted joists must be supported by headers.
Header:
a horizontal member that carries loads from other members and directs them around an opening.
in a floor system, a header is supported by
a trimmer joist.
Trimmer joist:
used to form the sides of a large opening
tail joist is a floor joist
interrupted by a header.
The exact layout of headers is based on the
flooring loads as well as the size and shape of the opening.
When the opening in a floor system causes a header to span more than 4’
double lengths of joist stock are generally used.
When you have an opening in the floor system, in the cast of an I joist flooring a X header is often used
LVL header
The difficulty of framing a stairwell depends on
whether the opening runs parallel to the floor joists, as in stairwells parralel to the floor joists, or perpendicular to them, as in stairwell perpendicular to joists.
