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- University of Idaho
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- Architecture 266
- Warnick
- Chapter 13 (Wood Light Frame Construction I)
Chapter 13 (Wood Light Frame Construction I)
Architecture 266 with Warnick at University of Idaho
About this deck
By: Ciera Shaver
Created: 2011-03-26
Size: 58 flashcards
Views: 5
Created: 2011-03-26
Size: 58 flashcards
Views: 5
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Where did wood light frame construction originate?
Early American buildings as European settlers colonized
Balloon Frame
original name for WLF construction
thin, closely spaced,vertical wood members (studs) and similar floor and roof membranes (joists and rafters)
advantage of WLF
light members= easy to install
Ribband: definition
the ledger that the intermediate floor joists rest on
Fire stops: definition
clog the air space between the studs; create a fire risk because the fire in the stud cavity can spread to that of the other floor
separate the cavities and deprive the fire of the oxygen required for its growth
What was the balloon frame modified into?
Platform Frame; individual studs are only one story high
subfloor: definition
provides a platform for the workers to stand on and to build the following story
how is a platform frame erected
story by story
Should you add fire stops in platform framing?
no; fire stops are automatically provided at each floor level because walls aren't continuous.
what did PF'ing make possible
tall buildings
balloon frame benefits?
continuity of the studs makes it dimensionally more stable; has a smaller overall cross-grain lumber dimension; shrinkage and swelling is smaller; greater structural stability and resist lateral loads
where does shrinking usually occur in wood?
against the grain
what can excessive shrinking and swelling cause, example?
nail popping and cracking of brittle finishes, like gypsum board and brick veneer
what do cross members do?
connect parallel members together to form a frame and play an important structural role
what is a rim/ band joist
the cross member at each end; a continuous member of the same size as the joist
what are most framing members in a WLF's dimensions?
2-by (1 1/2-by)
Double top plate: definition and function?
two members at the top pate in a wall assembly
allows the floor joists or rafters to be placed anywhere on the top plate
transfers gravity loads from the floor and roof to the studs
provides structural continuity in the top plate; producing tension and compression in the top plate under wind and earthquake loads
can counteract tension as long as joints are staggered
When is a third top plate needed and why?
if spacing between joists and rafters is more than 16 in. each joist or rafter should be located within 5 in of the underlying studs. if this can't be done, a third top plate is needed
Soul plate: definition, example
a plate that isn't in contact with the foundation (the bottom plate of the second floor)
sill plate: definition
bottom plate that is connected to the foundation
foundations for a WLF building (three types)
1. a concrete slab-on-grade
2. reinforced concrete (concrete masonry) foundation walls; wood frame floor with a crawl space
3. reinforced concrete basement walls; wood frame floor with a basement space below)
mud sill
AKA a sill plate
anchored to foundation with bolts
what is placed between sill and foundation to reduce air infiltration and how does it do this?
a compressible, fibrous belt helps to seal the gaps between the sill plate and the uneven surface of the foundation
what is a shear wall subject to and what is it caused by
tension at one end and compression at the other; caused by wall tending to overturn under wind action and earthquake loads
what is the compression caused by
lateral and gravity loads
why must three studs be at the corner of the walls
the corner of the exterior wall must be stronger than the field of the wall; they also give adequate nailing surfaces
jack stud: definition
a partial-height stud that supports the lintel beam
referred to as a header or lintel header
always accompanied by a king stud
header: definition
made of 2 or 3 2-bys
what types of headers are used for large openings
trussed headers, glulam headers
where is a cripple stud used?
above a header or below rough sill
what is the most crucial aspect of floor framing
layout of floor joists
when is an intermediate beam used?
when its impossible to use the walls as supports
what is a joist header and where can you find it?
a built-up beam; required where the joists are hung from a beam or joist header
what are floor joists prone to and why?
lateral buckling because the floor joists are slender
why are rim joists significant?
they provide lateral restraint, reducing their tendency to buckle
what are advantages of full-depth blocking?
they don't require a bevel-cut end
stiffens the floor and distributes the load between adjacent joists
why should rim joists be continuous?
continuity in a rim joist adds to the continuity of the wall's top plate
what are some commonly used roof shapes?
gable, hip and shed
what are the two types of roofs?
low-slope roof
steep roof
what is a low slope roof?
slope is less than 3:12
what is the difference between a truss or a rafter-and-ceiling joint assembly?
truss is a shop fabricated, multi-triangle frame
rafter-and-ceiling-joist assembly is a sire-fabricated, single triangle frame
what is a ridge board and what does it do?
the connection between two rafters is made through a continuous ridge board that runs perpendicular to the rafters; has no structural function
why must each rafter pair be tied together at the bottom?
to resist the outward thrust created by the gravity loads on the roof
what do ceiling joists do?
the tie (listed above)
the rafter pair and ceiling joist make a stable triangular frame which rests on two opposite supports and delivers a vertical load at the supports with no lateral thrust
why are the rafters notched at the bottom and what is it referred to?
to deliver the load vertically at the support and to have a horizontal bearing on the supporting walls; birds mouth
what are ceiling joists subject to?
tension and bending, due to gravity load from the attic
why is the intermediate support used?
usually an underlying wall
may be used to provide an additional support or rafters
what do purlins do?
reduce the size of rafters and increases the stiffness of the roof ; helpful in roofs that support large gravity loads
what type of loads are wind loads?
uplift loads, produce a separation of rafters at the ridge
what do collar ties do?
restrain the rafters from separating at the ridge; increases the rigidity of the joint between rafters at the ridge, decreasing the tension in the ceiling joists under gravity loads
what do ridge straps do?
basically the same as collar ties
don't obstruct the space in the attic
what are wood trusses?
an alternative to a stick-built rafter-joist assembly
ridge beams: definition
a structural member, bear on the ridge beam on the top and on the supporting walls at the eave.
in slopes greater than 3:12
what does wall sheathing do?
provides a nailing base
integrates the studs into a composite wall system
provides bracing to the frame against lateral loads
what is the most common material used for exterior sheathing?
OSB, as well as plywood, gypsum sheathing, and grid foam insulation
what is an alternative to panel-bracing?
diagonal let-in brace; 1x4 members fastened to studs that are notched to receive the brace; 45 and 60 degree angles; used when lateral loads are small
what kind of element is floor sheathing and why?
structural
it transfers floor dead and live loads to the joists
what kind of element is roof sheathing?
structural
About this deck
By: Ciera Shaver
Created: 2011-03-26
Size: 58 flashcards
Views: 5
Created: 2011-03-26
Size: 58 flashcards
Views: 5
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have been getting MUCH better grades on all my tests for school. Flash cards, notes, and quizzes are great on here. Thanks!”
Kathy
Kathy