Chapter 8: Building Construction

Lintel

"Header" Beam that spans an opening over a doorway or window

Cantilever Beam

A projecting beam supported at only one fixed end.

Hip Roof

A roof with four sloped sides

Overhanging Beam

A simple beam extending beyond one its supports.

Steel Overview, forms

Allow of iron, carbon, other additives which dictate the properties Pros: Compression, tension Cons: Expands and weakens very quickly with fire Not always required to have fire retardant Will expand 1% for every 1000 degrees Comes in forms of I-Beams, H-Columns, Rebar

Cinder Block

Concrete block, portland cement, water, aggregates 8"x8"x16"

Curtain Wall

Exterior, non-load bearing wall more than 1 story in height Supported by the frame of the structure Allows for lighter materials and thus highly decorative Eg. Omni Hotel

Scupper

Hole that is at roofline to allow water to drain out

Distributed Load

Load applied equally over wide area Eg. Roof

Torsion Loading

Load applied perpendicular to cross section of supporting member, does NOT pass through long axis

Concentrated Load

Load applied to concentrated point Eg. HVAC System

Fire Wall

Load bearing or non-load bearing Protects from fire intrusion Noted in larger structures due to their parapets that extend above roofline

Impact Load

Load in motion Caused by vibration, impact, acceleration Eg. Item falling

Door Stop

Material that prevents door from swinging past jamb

Efflorescence

Moisture seepage from material, salts and impurities are left behind

Retrofitting

the process of making older structures more earthquake resistant Horizontal steel rods in Masonry Walls, noted by the star plates on the exterior of the exterior walls where tie rods connect

Bottom Chord

the very bottom horizontal beam of a bridge truss

Gambrel Roof

A curb roof, having a steep lower slope with a flatter upper slope above.

Column

Any structural component that transmits compressive force or axial load

Foundation Overview Common Types

Base, responsible for all weight distribution, most resist all lateral forces Common types in SD Raised, Concrete Slab

Fixed Beam

Beam supported at two points and rigidly held in position at both points. This rigidity may cause collapse of a wall if the beam collapses and the rigid connection does not yield properly.

Simple Beam

Beam that is supported at two points near its end

Continuous Beam

Beam that is supported in three or more places

Girder Beam

Beam that supports other beams

Building Code Overview

Becomes law of a particular jurisdiction when formally enacted by appropriate authority. Cover: New construction and renovation Uniform Building Code: Primary building code in western US California Building Code: Stricter version of the UBC

Metal Roofing

Class I lightweight roofing Becoming more common in California Panels are placed on 2'x2' batten and 1'x4' counter-batten grid system, staggered like brickwork, nailed horizontally Cons: Roughly 4" of space between old and new roofing allows for fire spread

Woods

Common in construction industry: Douglas fir, Pine, Redwood Type 5 Construction

Parallel Trusses

Commonly found in newer commercial and concrete tilt-up construction Considered lightweight construction Ex. Home Depot, Costco Types 1. Wood 2. Wood chords, steel web 3. Steel

Wooden I Joist

Composite lightweight wood material used in an "I" cross-section Top and bottom chords are often as small as 2"x3" Plywood or OSB stem can be as thin as 3/8" Residential and commercial roofing and flooring

Types of Load Forces on Structure

Compression: Shortening Tension: Elongation Shear: Tear/ Slide apart

Balloon Walls

Construction pre-WWII Many older commercial and multi-story residentials still in SD

Lightweight Concrete

Corrugated metal decking is attached to wood or steel framing Mix of sand, cement, and small aggregate is pumped on top of metal decking of about 3" to 4" Concrete and rubberized roof membrane placed over it Con: Difficult to ventilate

Design vs Undesigned Load

Designed: Load that has been calculated/ anticipated Undesigned: Not anticipated when constructed; common in remodels Eg. Office building converted into warehouse

Web

Diagonal cross braces that create a triangular pattern between the top and bottom chords

Types of Deformation on Structure

Elastic: Material returns to original shape Yielding: Material does not return to original shape Ductie: Large amount of deformation before failure Brittle: Material shoes little to no deformation prior to failure

Raised Foundation Diagram, Overview

Found in homes built before 1950 Weight of home distributed between exterior stem wall and posts installed underneath to piers

Concrete Walls

Found in most new low-rise commercial construction using "tilt-up" method, rely on roof for stability

Lath & Plaster

Handcrafted, skilled technique, fell out of favor in 1930's-40's due to less expensive, quicker techniques Wood nailed horizontally, covered in plaster

Wood Door Types

Hollow Core: Wood strips and glue form honeycomb shape, plywood veneer paneling Solid Core: Particle core, tongue and groove wooden board glued; others are compressed material with fire retardant, plywood veneer covering

Ridge Pole

Horizontal beam at the ridge of a roof to which the rafters are attached

Header

Horizontal member over window or door

Sill

Horizontal member under window

Joist

Horizontal supporting members that run from wall to wall, wall to beam, or beam to beam to support a ceiling, roof, or floor

Hot Mop and Rock

Hot tar to be spread onto plywood or OSB, followed by asphalt-impregnated felt rolled over top. Small rock or aggregate is spread onto still-hot asphalt For play roofs Cons: This type of roof can fail quickly

Conventional Roof Structure

Less common today that was used predominately 50 years ago Large wooden members (2x10's, 2x12's) and solid wood or laminated beams were used to build framework of the roof Many conventional and residential structures Rafters, plywood or 1x6 wood sheathing for roof material Pros: Strong, hold up to fire longer

Mortar

Lime, sand, water, generally weakest link in masonry construction

Interior Walls

Load or non-load bearing No insulation Covered with any combination of: Lath & plaster, drywall, wood paneling, other

Eccentric Loading

Load that does NOT pass through center of mass, load is perpendicular to the cross section

Axial Loading

Load that passes through center of mass of supporting element, perpendicular to cross section

Parging

Masonry-based mortar trowelled directly onto surface of masonry brick Eg. Gaslamp, Downtown

Spalling

Moisture trapped within expands and causes damage, even explosion

Veneer Walls

Non-load bearing, decorative, typically only tied to main structure using metal ties every 16 inches

OSB

Oriented Strand Board Wood-based panel made by gluing several layers of wood strands under heat and pressure so that the adjacent layers are oriented in opposite directions

Masonry

Overview: Building of structures from individual units laid in and bound together in mortar, walls of buildings, retaining walls, monuments Ex: 12"x12" Hollow clay block used in older parts of SD Pros: Highly durable, compression Cons: Weak with horizontal or lateral loads, needs compression

Stone

Overview: Often laid or set without bonding agent, dry-stacking Ex: Granite, limestone, sandstone, marble Pros: Hard, durable, thick Cons: Extreme weight Cautions: Not very common in SD, commonly used as coverings and facades in California

Platform Wall Construction

Post-WWII

Sole Plate

Pressure treated lumbar, bottom horizontal member of frame

Post-Tensioned Rebar

Rebar placed in protective sleeve and concrete poured around and anchored

Pre-Tensioned Rebar

Rebar placed under tension prior to concrete poor, then slowly released

Concrete Slab Diagram, Overview

Reinforced concrete to create slabs to support structure Found in new residencial and all commercial

Asphalt Composite Roll

Rolls of 3'x30' Very popular in commercial and residential structures with a flat or low pitch roof Common for new layers to be placed over old layers

Party Walls

Separate tenants in apartments or condos, may or may not be load bearing

Purlin

Series of beams placed perpendicular to other beams or trusses to support large area roofs and decking

Rafter

Series of sloped beams that extend from ridge or hip to downslope perimeter or eave

Wood Shake Shingles

Shingles or shakes, split pieces of red cedar wood used for roofing or siding Usually attached to 1"x6" skip sheeting Newer shingles are now tx with fire retardant

Tile Roofing

Slate, Clay, Concrete Clay and concrete tile can be Spanish style or Flat Found on pitched roofs in new and old residentials in SD Cons: Signs of roof integrity are masked, slippery when wet, ridge caps must be removed before roof ladder placement, tiles are heavy

Door Strike

Strike Plate: Typically metal plate covers receptacle in door frame for deadbolt or latch

Door Jamb Define Types

Structural boarder or track which door is set, supports stop of door. Rabbeted Jamb: Jamb & stop is one unified piece, common in metal frames Stop Jamb: The stop is wood or metal attached, common in wood frame

Beam

Structural element that transfers loads perpendicular to its length Forces causes top to be in compression and bottom to be under tension Types of beams: Girder, simple, continuous, purlin, joist, ridge pole, rafter, lintel/header

Concrete

Synthetic, cement, fine aggregates, coarse aggregates, water Reinforced with rebar Withstands extremely high compression Poor with tensile strength 28 days till full strength

Fire Load

The potential heat generated by all structural components of building and components BTU's

Plywood

Thin wood plies glued together Found in 4'x8' sheets Roofing component

Asphalt Composition Shingles

This shingle consists of a fiberglass mat Impregnated with asphalt Faced with granular stone aggregate Plywood over rafters with shingles stapled/nailed Ex. Very common in pre-1980's residentials with a pitch in SD Con: Material will melt and burn

Top Plate

Top horizontal member of frame

Top Chord

Top horizontal member of the truss In compression when loaded

Imposition of Loads

Transfer of weight, static or dynamic, on structural components of building

Lightweight Engineered Truss Construction

Trusses built in assembly line fashion Commercial and residential applications Roofs or floor construciton

Panelized Roof Construction

Typically found on commercial structures constructed of wood, masonry, or concrete tilt-up slabs Considered lightweight construction in some parts More common for roofs, also found in floors No space between ceiling and roof Beams, purlins, joists, decking - main components Laminating beams of various sizes (6"x36" is common for long distances) Beams are supported at ends by posts or pilasters with additional posts along the span Beams may be 12' to 40' in length and bolted together to create over 100'

Exterior Walls

Typically load bearing Concrete, masonry, vinyl, stucco, wood, steel Insulation

Hinges Two Categories Number Used

Unsealed: Pin connecting the hinge can be removed Sealed: Pin connecting the hinge cannot be easily removed Two: Light Weight/ Hollow Doors Three: Commercial or solid doors

Masonry Walls

Used in low-rise commercial buildings, no longer code to use un-reinforced masonry

Studs

Vertical framing members 12, 16, 24 inches apart

Cripple

Vertical studs below or above

Lightweight Roof Construction

Very popular around the country currently Standard over last 25 years

Examples of New Composite Building Materials

Vinyl Plastic Fiberglass Glue Aluminum Styrofoam Fiber Board Lowered flash points, toxic gases, fails quickly

Live Load

Weight of occupants, furniture, moveable equipment, forces of movement

Dead Load

Weight of the building and permanent components; static

Wall Construction

Wood and lightweight steel common in residential and interior commercial Concrete and masonry typically exterior walls in commercials in SD

Butterfly Roof

a V-shaped roof in which the two sides slope toward a valley in the middle

Gusset Plate

a flat plate used for joining structural elements

Truss

a framework, typically consisting of rafters, posts, and struts, supporting a roof, bridge, or other structure.

Parapet

a low protective wall along the edge of a roof, bridge, or balcony

Gable Roof

a pointed part of a roof, forming a triangle

Pilasters

a rectangular column, especially one projecting from a wall.

Shed Roof

slopes to one side