76 terms

Design Science 1 Lecture 3

key terms and questions
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Wood light frame construction
developed when builders recognized that the closely spaced vertical members used to infill the walls of a heavy timber building frame were themselves sufficiently strong so that the heavy posts of the frame could be eliminated
Balloon frame
a wooden building frame composed of closely spaced members nominally 2 inches thick, in which the wall members are single pieces that run from the sill to the top plates at the eave
Joist
one of a parallel array of light, closely spaced beams used to support a floor deck (floor joist) or low-slope roof (ceiling joist)
Stud
one of an array of small, closely spaced, parallel wall framing members; a heavy steel pin
Rafter
a framing member that runs up and down the slope of a steep roof
Firestop
a component or mastic installed in an opening through a floor or around the edge of a floor to retard the passage of fire; frequently used interchangeably with fireblocking
Platform frame
a wooden building frame composed of closely spaced members nominally 2 inches thick in which the wall members do not run past the floor framing members
Sheathing
the rough covering applied to the outside of the roof, wall, or floor framing of a structure
Header
in framed construction, a member that carries other perpendicular framing members, such as a beam above an opening in a wall or a joist supporting other joists where they are interrupted by a floor opening. For steel construction, a beam that spans between girders. In masonry construction, a brick or other masonry unit that is laid across two wythes with its end exposed in the face of the wall
Rim joist
(same as band joist) a wooden joist running perpendicular to the primary direction of the joists in a floor and closing off the floor platform at the outside face of the building
Band joist
a wooden joist running perpendicular to the primary direction of the joists in a floor and closing off the floor platform at the outside face of the building
Subfloor
the loadbearing surface beneath a finish floor
Sole plate, bottom plate
the horizontal piece of dimension lumber at the bottom of the studs in a wall in a light frame building
Top plate
the horizontal member at the top of the studs in a wall in a light frame building
Ridge board
a nonstructural framing member against which the upper ends of rafters are fastened
Trimmer
a joist that supports a header around an opening in a floor or roof frame
Sill
the horizontal bottom portion of a window or door; the exterior surface, usually sloped to shed water, below the bottom of a window or door
Wracking
forcing out of plumb
Permanent wood foundation
can be constructed in any weather; readily insulated in the same manner as the frame of the house they support; easily accommodate the installation of electrical wiring, plumbing, and interior finish materials
Batter board
: boards mounted on stakes outside the excavation area of a building, used to preserve locations for string lines marking the corners of the building foundation
Termite shield
: a metal flashing placed on top of a concrete foundation to prevent termites from traveling undetected from the ground into the superstructure
Framing plan
a diagram showing the arrangement and sizes of the structural members in a floor or roof
Section detail
an architectural drawing representing a vertically cut plane through a whole building, part of a building, or detail
Architectural floor plan
serve to indicate the locations and dimenstions of walls, partitions, and opening
Exterior elevation
show the outside faces of the building, with vertical dimensions or elevations indicated as required
Building section
: cut completely through the building, showing the dimensional relationships of various floor levels, roof planes, and slopes of roof surfaces
Interior elevation
prepared for kitchens, bathrooms, and other rooms with elaborate interior features
Rough carpentry
framing carpentry, as distinguished from finish carpentry
Foundation sill plate
usually made of preservative-treated wood for added resistance to insects and moisture; bolted to the foundation as a base for the wood framing
Sill sealer
a compressible material placed between a foundation and a sill to reduce air infiltration between the outdoors and indoors
Bridging
: bracing or blocking installed between steel or wood joists at mid-span to stabilize them against buckling and, in some cases, to permit adjacent joists to share loads
Blocking
pieces of wood inserted tightly between joists, studs, or rafters in a building frame to stabilize the structure, inhibit the passage of fire, provide a nailing surface for finish materials, or retain insulation
Trimmer, jack stud
a shortened stud that carriers a header above a wall opening
King stud
a full-length stud nailed alongside a jack stud
Rough sill
at the bottom of a window opening, this is supported on cripple studs
Cripple stud
a wood wall framing member that is shorter than full-length studs because it is interrupted by a header or sill
Shear wall
a stiff wall that imparts lateral force resistance to a building frame
Hold-down
prevent walls from pulling up off the foundation or floor platform
Let-in diagonal bracing
bracing that is nailed into notches cut in the face of the studs so as not to increase the thickness of the wall
Flat roof
a roof that has no elevation or skewed angles; sits flat, perpendicular to the supporting walls underneath it
Shed roof, single-pitch roof
a roof with a one-directional slant; like a flat roof at a tilt
Gable roof
a roof consisting of two oppositely sloping planes that intersect at a level ridge
Hip roof
a roof consisting of four sloping planes that intersect to form a pyramidal or elongated pyramid shape
Gambrel roof
a roof shape consisting of two superimposed levels of gable roofs with the lower level at a steeper pitch than the upper
Mansard roof
roof shape consisting of two superimposed levels of hip roofs with the lower level at a steeper pitch than the upper
Ceiling joist
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Ridge beam
a structural beam supporting the upper ends of rafters in a sloped roof, required where the rafters are not ties at their lower ends
Knee wallpitch
a short wall under the slope of a roof
Rise
a difference in elevation, such as the rise of a stair from one floor to the next or the rise per foot of a run in a sloping roof
Run
horizontal dimension in a stair or sloping roof
Framing square
an L-shaped measuring tool used by carpenters to lay out right-angle cuts as well as more complicated cuts, such as those required for stairs and sloping roof rafters
Hip
the diagonal intersection of planes in a hip roof
Valley
: a trough formed but the intersection of two roof slopes
Pattern rafter
a wood rafter cut to size and shape and then used to trace cuts onto additional wood members to as to assure consistent dimensions among all rafters
Collar tie
a piece of wood nailed across two opposing rafters near the ridge to resis wind uplift
Dormer
a structure protruding through the plane of a sloping roof, usually containing a window and having its own smaller roof
Birdsmouth cut
an angled notch cut into a rafter to allow the rafter to seat securely on the top plate of a wall
Common rafter
a roof rafter that runs parallel to the mail slope of the roof (see hip rafter)
Valley rafter
a diagonal rafter that supports a valley
Hip rafter
a roof rafter at the intersection of two sloping roof planes (see common rafter)
Fascia
the exposed vertical face of an eave
Lookout
a short rafter, running perpendicular to the other rafters in the roof, which supports a rake overhang
Fly rafter
a rafter in a rake overhang
Rake
the sloping edge of a steep roof
Plumb cut
a saw cut that produces a vertical (plumb) surface in a sloping rafter after the rafter is in its final position (see level cut)
Level cut
a saw cut that produces a level surface in a sloping rafter when the rafter is in its final position
Advanced framing techniques, optimum value engineering
a wood light framing system that minimizes redundant framing members, reducing the amount of lumber required and increasing the thermal efficiency of the insulated frame
Roof truss
used in platform frame buildings because of its speed of erection, economy of material usage, and long spans
Floor truss
used (to a lesser extent) in platform frame buildings because of its speed of erection, economy of material usage, and long spans
Draw a series of very simple section drawings to illustrate the procedure for erecting a platform frame building, starting with the ground floor, the ground-floor walls, the second floor, the second-floor walls, and the roof. Do not show any details of connections but simply represent each plane of framing as a heavy line in your section drawing.
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.) Draw from memory the standard detail sections for a two-story platform frame dwelling. Hint: the easiest way to draw a detail section is to draw the pieces in the order in which they are put in place during construction. If the drawings from question one are correct, this should not be too difficult.
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What are the differences between balloon framing and platform framing? What are the advantages and disadvantages of each? Why has platform framing become the method of choice?
Balloon framing: the studs run in one piece from the sill to the rafter plate
-has less vertical shrinkage from drying out of the wood
Platform framing: the studs are interrupted by floor platforms
-easier and safer to erect
- uses shorter lengths of lumber for studs
-automatically firestopped
Why is little added fire-stopping required in platform framing?
Firestop is inherently created by the double top plate at each floor
Why is a steel beam or glue-laminated wood beam preferred to a solid wood beam at the foundation level?
A wood beam under the ground floor of the platform frame will dry and shrink, allowing the floor to tilt, while steel beam will not.
A glue-laminated wood beam is an acceptable substitute for a steel beam because it is made of thoroughly seasoned wood and will be fairly stable dimensionally
How is a platform frame building braced against wind and earthquake forces?
A platform frame building is braced laterally by let-in diagonal bracing at the corners, by rigid sheathing such as plywood panels or by diagonal sheathing boards
Light framing of wood is highly combustible. In what different ways does a typical building code take this fact into account?
Building codes restrict height and size of buildings built out of light wood framing to keep occupant loads low and escape routes short. Smoke and heat alarms installed. Bedroom windows must be large enough to permit emergency passage of reisdents and firefighters. Encourage us of fire-resistant materials. Automatic sprinkler systems a requirement for some types of light wood frame buildings
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