chapter 17: constructing structures - g-w.com · chapter 17 constructing structures learning...

Chapter 17Constructing Structures

Learning ObjectivesAfter studying this chapter, you will be able to:

� List the two types of construction.

� Describe the major types of buildings that are constructed.

� Identify the steps involved in constructing a structure.

� Identify the types of foundations.

� Describe the framework used in buildings.

� Describe how buildings are enclosed.

� Explain the types of utility systems used in buildings.

� Describe materials used in finishing buildings.

� Identify other types of buildings.

� Identify the characteristics of heavy engineering structures.

Human beings have three basic needs:food, clothing, and shelter. Each of these canbe satisfied using technology. Agricultureand related biotechnologies help us grow,harvest, and process food. Manufacturinghelps us to produce natural and syntheticfibers. These fibers become the inputs toclothing and fabric manufacture. Materialsand manufactured goods can be fabricatedinto dwellings and buildings using con-struction technology. Construction usestechnological actions to erect a structure onthe site where it will be used.

Types of StructuresConstruction builds two types of struc-

tures. These are buildings and heavy engi-neering structures, Figure 17-1. Buildings areenclosures to protect people, materials, andequipment from the elements. Buildingsalso provide security for people and theirbelongings. Heavy engineering structureshelp our economy function effectively.

BuildingsBuildings are grouped into three types:

residential, commercial, and industrial,Figure 17-2. These groupings are based

319

on how the buildings are used. Note, how-ever, that other types of buildings exist.These special buildings follow the sameconstruction steps as the other buildings.This section will describe each of the maintypes, provide an overview of the other types,and discuss the general steps involved inconstructing buildings.

Residential BuildingsResidential buildings are buildings in

which people live. These buildings can besingle-family or multiple-unit dwellings.The multiple-unit dwellings include apart-ments, town houses, and condominiums.

A residential building can be eitherowner occupied or rented from the owner.The owner of a dwelling is responsible forits upkeep. In some types of dwellings,such as condominiums, the costs of upkeepare shared between the owners. Eachowner belongs to and pays fees to an asso-ciation. This group elects officers who man-age the maintenance of common areas suchas entryways, garages, parking areas, andlawns. The association is also responsiblefor exterior repairs and insurance on thebuilding. The individual owners maintain

their own living quarters and insure theirpersonal belongings against fire and theft.

Commercial BuildingsCommercial buildings are used for busi-

ness and government purposes. Thesebuildings can be publicly or privatelyowned. Commercial buildings range insize from small to very large. Retail stores,offices, courthouses, schools, libraries, andwarehouses are commercial buildings.

Industrial BuildingsIndustrial buildings house the machines

that make products. These buildings areused to protect machinery, materials, andworkers from the weather. The buildingsupports the machines and supplies theutility needs of the manufacturing process.Many industrial buildings are speciallybuilt for one manufacturing process.

Other Types of BuildingsYou see commercial, industrial, and

residential buildings all around you. Ifyou look around your town or city, how-ever, you will probably see other types ofbuildings, Figure 17-3. These may include:

Chapter 17 Constructing Structures

Types of Construction Projects

Buildings Heavy Engineering Structures

Figure 17-1. Construction erects buildings and heavy engineering structures.

This sample chapter is for review purposes only. Copyright © The Goodheart-Willcox Co., Inc. All rights reserved.

� Monuments: These structures pay trib-ute to the accomplishments or sacrificesof people or groups.

� Cultural buildings: These buildingshouse theaters, galleries, libraries, per-formance halls, and museums. Thesebuildings host musical, dramatic, anddance performances, literary activities,and art exhibits.

� Government buildings: These build-ings house government functions.Examples include city halls, postoffices, police stations, firehouses, statecapitols, courthouses, and governmentoffice buildings.

� Transportation terminals: These build-ings are used to aid in the loading andunloading of passengers and cargo fromtransportation vehicles. Examples areairports, train and bus stations, freightterminals, and seaports.

� Sports arenas and exhibition centers:These facilities are used for sportingevents, concerts, trade shows, andconventions.

� Agricultural buildings: These struc-tures include barns and storage build-ings used to house livestock, sheltermachinery, and protect farm products(grain and hay, for example).

As noted earlier, these special buildingsare built using the same construction stepsused for a single-family home.

A special type of building is the manu-factured home. As you will remember, man-ufacturing produces products in a factory.The completed product is transported to itsplace of use. This is exactly how manufac-tured homes are produced, Figure 17-4.Most of the structure is built in a factory.This type of home is usually built in twohalves. The floors, walls, and roof areerected; then the plumbing and electricalsystems are installed. The structure’s inte-rior and exterior is enclosed and finished.This step includes installing flooring,painting walls, setting cabinets and plumb-ing fixtures, and installing appliances andelectrical fixtures.

The two halves of the structure aretransported to the site. The foundation isalready in place. Each half is lifted from itstransporter and placed on the foundation.The two halves are finally bolted together.The final trim that connects the halves isinstalled. The utilities are hooked up, andthe home is ready for the homeowner.

Similar techniques are used to producetemporary classrooms, construction offices,and modular units that can be assembledinto motels or nursing homes.

320 Section 5 Applying Technology: Producing Products and Structures

Types of BuildingsR

esid

enti

alC

om

mer

cial

Ind

ust

rial

Figure 17-2. Construction is used to build res-idential, commercial, and industrial buildings.(Marvin Windows and Doors, Inland SteelCompany)

321Chapter 17 Constructing Structures

Sydney Opera House

Hoosier Dome

Grain Elevators

Statue of Liberty

United States Capitol

Figure 17-3. Buildings other than the three main types can be found in many forms.

Build in Factory Move to Site Lift from Truck

Set on Foundation Finish Ready to Move in

Figure 17-4. Shown here are the steps in building a manufactured home.


Section 5 Applying Technology: Producing Products and Structures322

Constructing BuildingsMost construction projects follow the

same basic steps. These steps, as shown inFigure 17-5, include the following:

� Preparing the site

� Setting foundations

� Building the framework

� Enclosing the structure

� Installing utilities

� Finishing the exterior and interior

� Completing the site

Each type of structure needs to havespecific actions taken during each step.This helps complete the structure on time.We will look at the steps used to constructa small single-family home. Later in thechapter, other construction activities willbe discussed.

A common type of building is a single-family home. It is designed to meet a num-ber of needs of the owners. These needs, asshown in Figure 17-6, include protectionfrom the weather, security, and personalcomfort. To meet these needs a home must

be properly designed and constructed. Theconstruction process starts with locating,buying, and preparing a site.

Preparing the SiteThe location for a home needs to be

carefully selected. It should meet the needsof the people who will live there. For exam-ple, a family with children may think aboutthe schools serving the area. The parentswill consider the distance to work, shop-ping, recreation, and cultural facilities. Thecondition of other homes in the neighbor-hood, building codes, and covenants areother factors to consider.

Once the site is chosen, it is purchasedfrom the original owner. This may requireworking with a real estate agent andobtaining a bank loan or other financing.The financing will probably include themoney to erect the home. This is importantbecause most banks will not loan money tobuild a house on land that is mortgaged.

Next, the site is cleared to make roomfor the structure. The location of the newbuilding is marked out. Then, that area iscleared of obstacles. When it is possible, the

Preparing the Site

Setting Foundations

Building the Framework

Enclosing the Structure

Installing Utilities

Finishing the Exterior and Interitor

Completing the Site

Figure 17-5. Most construction projects follow the same basic steps. (Gehl Co.)

323

building should be located to save existingtrees and other plant life. The site mayrequire grading, Figure 17-7, to level the site.Grading prepares areas for sidewalks andlandscaping and helps water to drain fromthe site. These preparations are needed forthe next step, setting foundations.

Setting FoundationsThe foundation is the most important

part of any building project. The founda-tion serves as the “feet” of the building. Tryto stand on just your heels. You will be

unstable and wobble. Likewise, a buildingwithout a proper foundation will settleunevenly into the ground. It will lean,become unstable, and may fall to theground. The Leaning Tower of Pisa in Italyis an example of a building that has a poorfoundation. Over time, the tower has set-tled and is leaning several feet to one side.

A complete foundation has two parts:the footing and the foundation wall, Figure 17-8. The footing spreads the loadover the bearing surface. The bearing sur-face is the ground on which the foundationand building will rest. This can be rock,sand, gravel, or a marsh. Each type of soiloffers unique challenges for the construc-tion project.

The type of foundation to use isselected to match the soil of the site. Threetypes, as shown in Figure 17-9, are:� Spread foundations: These types of

foundations are used on rock and inhard soils such as clay. The foundationwalls sit on a low flat pad called a foot-ing. On wide buildings, posts supportthe upper floor between the foundationwalls. These posts also rest on pads ofconcrete called footings.

Chapter 17 Constructing Structures

Keep out Rain, Snow,

and SleetProtect from Sun

ExcludeMoisture

ControlAccess

Insulate from

Sound and Heat

Withstand Wind

Admit Light

Allow for Viewsand Ventilation

Figure 17-6. This diagram shows some of the needs a home must meet for its owner.

Figure 17-7. Before a building can be built,the site must be cleared and graded.


324

� Slab foundations: These types of foun-dations are used for buildings that arebuilt on soft soils. They are sometimescalled floating slabs. The foundationbecomes the floor of the building. Suchfoundations allow the weight of thebuilding to be spread over a wide area.This type of foundation is used inearthquake areas because it can with-stand vibration.

� Pile foundations: These types of foun-dations are used on wet, marshy, orsandy soils. Piles are driven into theground until they encounter solid soil orrock. Piles are large poles made of steel,wood, or concrete. They are widely usedfor high-rise buildings, marine docks,and homes in areas that flood easily.

Each type of foundation is built in aunique way. Let us consider a spread foun-dation. The site is surveyed to locate thefoundation, Figure 17-10. Then the site isexcavated in preparation for the footingsand the walls. If the building is to have nofootings, excavation does not go as deep.Buildings with basements require deeper

Section 5 Applying Technology: Producing Products and Structures

FoundationWall

Footing

Figure 17-8. The foundation wall and footing spread the building’s weight onto the bearing sur-face. The concrete foundation shown in the photo has been insulated to reduce heat loss.

SpreadFoundation

PileFoundation

SlabFoundation

Figure 17-9. Three types of foundations usedfor buildings are spread, slab, and pile.

excavations. Footing forms are set up next.Forms are a lumber frame to hold the wetconcrete until it cures (hardens). Formsgive the footings or slabs height and shape.Concrete is poured and leveled off. Whenthe concrete is cured, the forms are

removed. Walls of poured concrete or con-crete block are built atop footings. Slabs areready for aboveground superstructures.Figure 17-11 shows an excavation for apool. Wooden foundations use no concretefor either footings or walls.

Chapter 17 Constructing Structures 325

Figure 17-11. This worker is excavating ahole for a pool.

Career Corner

CarpentersCarpenters help construct build-

ings, highways, bridges, factories, andother structures. Some carpenters do alltypes of work, while others specialize indoing a specific job, such as settingforms for concrete, framing walls andpartitions, laying hardwood floors, orinstalling interior and exterior trim.Carpenters must know local buildingcodes and be able to work from blue-prints or instructions from supervisors.

Those who remodel homes must be able to do all aspects of a job and, therefore, requirea good basic overall training.

Carpentry work is somewhat strenuous and requires standing, climbing, bending,and kneeling. Carpenters must be competent in using tools and power equipment.Carpentry is considered a skilled trade. Most carpenters learn their trade through on-the-job training, vocational education, or apprenticeships.

Figure 17-10. This worker is surveying a sitefor a new building. The survey will locate wherethe foundation will be placed. (Inland Steel Co.)


Building the FrameworkThe foundation becomes the base for the

next part of the building, the framework.Erecting the framework gives the buildingits size and shape. The framework includesthe floors, interior and exterior walls, ceil-ings, and roof. Also, the location of doorsand windows are set up at this time.

The framework can be built out of threedifferent materials, Figure 17-12. Small andlow-cost buildings have frameworks madefrom lumber. Industrial and commercialbuildings have either steel or reinforcedconcrete frameworks.

Building the framework involvesthree steps. First, the floor is constructed,Figure 17-13. Homes with slab founda-tions use the surface of the slab as thefloor. Homes with basements or crawlspaces use lumber floors.

Lumber floors start with a wood sillthat is bolted to the foundation. Floorjoists are then placed on the sill. Theyextend across the structure. Floor joistscarry the weight of the floor. The size andspacing of the joists will be determinedby the span (distance between outside

walls) and the load on the floor. On top ofthe joists a subfloor is installed, usuallymade from plywood or particleboard.After the building is enclosed flooring mate-rial will be installed on top of the subfloor.


Steel ReinforcedConcreteLumber

Figure 17-12. The materials used for framework are lumber, steel, and reinforced concrete.S

lab

Flo

or

Lu

mb

er F

loo

r

Subfloor

FloorJoist

Sill

Foundation

Figure 17-13. The floors in single-familyhomes are either concrete slabs or lumber.

The wall frames are placed on top of thefloor. These frames support both exteriorand interior walls. Wall framing is oftenmade of 2 x 4 or 2 x 6 construction-gradelumber, Figure 17-14. A framed wall has astrip at the bottom called the sole plate.Nailed to the sole plate are uprights calledstuds. The length of the studs is set by howhigh the ceilings will be. At the top of thewall the studs are nailed to double ribbonsof 2 x 4s called a top plate or wall plate.Door and window openings require head-ers above them. Headers carry the weightfrom the roof and ceiling across the doorand window openings. Headers are held upby shorter studs called trimmer studs.

The walls support the ceiling and roof,Figure 17-15. The ceiling is the inside sur-face at the top of a room. The roof is the topof the structure that protects the housefrom the weather.

Ceiling joists support the ceiling. Thesejoists rest on the outside walls and someinterior walls. Interior walls that help sup-port the weight of the ceiling and roof arecalled load-bearing or bearing walls.

The roof forms the top of the building.There are many types of roofs including flat,gable, hip, gambrel, and shed, Figure 17-16.The type of roof is chosen for its appearanceand how it withstands the weather. Forexample, flat roofs are poor choices in areaswith heavy snow. This type of roof cannoteasily support the weight of deep snow.Likewise, a hip roof would look out of


Sheathing

Rafter

CeilingJoist

DoubledTop Plate

Stud

Figure 17-15. This illustration shows how theroof meets the wall frame.

Doubled Top Plate Trimmer Stud

Header

WindowOpening

DoorOpening

TrimmerStud

Stud

SolePlate

Cripple Stud

Figure 17-14. This photo shows many of the parts of a wood-framed wall.


place on Spanish-type homes. This kindof roof would not give the “Spanish-style”look.

Roof construction involves two steps.First, the roof frame is built with rafters.Rafters are angled boards that rest on thetop plate of the exterior walls. Often a spe-cial structure called a truss is used. A trussis a triangle-shaped structure that includesboth the rafter and ceiling joist in one unit.Trusses are manufactured in a factory andthen shipped to the building site.

The rafters or trusses are covered withplywood or particleboard sheathing. Thisstep completes the erection of the frame.

Enclosing the StructureAfter the framework is complete the

structure needs to be enclosed. The roofand wall surfaces need to be covered. Thisprocess has two steps: enclosing the wallsand installing the roof.

With regard to enclosing the walls, weshould note that all homes have both inte-rior and exterior wall coverings. Thesecoverings improve the looks of the build-ing and keep out the elements (rain, snow,wind, and sun).

The first step is enclosing the exteriorwalls, Figure 17-17. This involves sheath-ing (covering) all the exterior surfaces.Plywood, fiberboard, or rigid foam sheetsare used to sheath the walls. Most foamsheets have a reflective backing to improvethe insulation value of the sheet. Mosthomes constructed today have a layer ofplastic over the sheathing to prevent airfrom leaking in.

With regard to roof installation, nor-mally the roof is put in place before the util-ities are installed, Figure 17-18. The actualroof surface has two parts. Sheathing isapplied over the rafters. This sheathingmay be plywood or waferboard. Now theroofing material is installed. Builder’s feltis often applied over the roof sheathing.Wood or fiberglass shingles, clay tile, ormetal roofing is then installed over thesheathing and felt. Flat and shed roofsoften use a built-up roof. A built-up roofstarts with laying down sheets of insula-tion. Roofing felt is laid down, followed bya coat of tar, which is covered with gravel.

On many structures the overhang of theroof is also finished. A fascia board is usedto finish the ends of the rafters and the


Gable

Side View Side View Side View Side View Side View

Flat Hip Gambrel Shed

Figure 17-16. Shown here are some popular types of roofs used on homes.

overhang. The soffit is installed to enclosethe underside of the overhang. The soffitcan be made of aluminum, vinyl, or ply-wood. Soffits must have ventilation holesor vents to prevent moisture and heat buildup in the attic.

Once the sheathing and roof areinstalled, the openings for doors and win-dows are cut out. Then the doors and win-dows are set in place. Now the house issecure and weather tight.

Installing UtilitiesNormally the utilities are installed after

the building has been enclosed. This pre-vents theft and damage from the weather.Some parts of the utilities are installed ear-lier, such as large plumbing lines. The util-ity system includes four major systems:

� Electrical

� Plumbing

� Climate control

� Communications


Lu

mb

er F

loo

r

Rafter

Vent

Roof Sheathing

Shingles

Soffit Fascia

Figure 17-18. These are the parts of a fin-ished roof. The photo shows asphalt shinglesbeing installed on a new roof.

Ceiling Joist

CeilingBrick

Sheathing

Stud

Flooring Subfloor

Drywall

Floor Joist

Figure 17-17. This is a cross-section diagram of a finished wall. The photo shows brick beingapplied as a siding material.


ElectricalThe electrical system delivers electrical

power to the different rooms of the home.The power is brought into the house throughwires to a meter and distribution panel. Thispanel splits the power into 110-volt and 220-volt circuits. Each circuit has a circuit breakerto protect against current overloads.

Appliances such as clothes dryers, elec-tric ranges, water heaters, and air condi-tioners require 220-volt power. Circuitsfor smaller appliances use 110 volts.Outlets may have power fed to them at alltimes. Outlets can also be controlled byswitches. Figure 17-19 shows a 110-voltcircuit with wall (duplex) outlets and aceiling light. You will note that the outletswill always have power. The circuit to thelight has a switch, however.

Most 110-volt circuits are limited to 15or 20 amps. Therefore, a number of differ-ent circuits are required to supply variousparts of the home. A kitchen might haveone or two circuits because of how many

appliances are used there. One circuitmight feed two bedrooms because there arefew appliances in these rooms.

PlumbingThe plumbing system has two sepa-

rate parts. One part supplies potable water,Figure 17-20. Potable water is safe fordrinking. The other part of the system car-ries away wastewater. Plumbing fixturesand systems are designed to prevent mix-ing of potable water and wastewater andto stop sewer gas from leaking into thedwelling.

The potable water system starts with acity water supply or a well for the house.The water enters the house through a shut-off valve. The water may pass through awater conditioner. This device removesimpurities such as iron and calcium.

The water line is split into two branches.One line feeds the water heater. The otherline feeds the cold water system. Separatehot and cold water lines feed fixtures inthe kitchen, bathrooms, and utility room.


IncomingPower

Outlets Switch

Light Fixture

Wire ColorsBlackWhiteGreen or Bare

CircuitBreaker

Box

Figure 17-19. This diagram shows a 110-volt electric circuit. Note how the light is controlled by theswitch but the outlets are not.

Toilets, however, receive only cold water.Most water lines have shutoff valves beforethey reach the fixture.

For example, the water lines under asink should have a shutoff valve. The valveallows repairs to be made without stoppingthe water flow to the rest of the house.

The second part of the plumbing sys-tem is the wastewater system. This systemcarries used water away from sinks, show-ers, tubs, toilets, and washing machines.The wastewater is routed to a city sewerline or to a septic system. At each of thesefixtures and appliances, a device called atrap is provided. A trap is a U-shapedpiece of pipe that remains full of water. Thewater in the line stops gases from thesewer system from leaking into the home.Wastewater systems have a network ofvents to prevent the water from beingdrawn out of the traps. The vents alsoallow sewer gases to escape above the roofwithout causing any harm.

Homes that use natural gas have athird type of plumbing. Gas lines carrynatural gas to furnaces, stoves, water

heaters, and other appliances. Shutoffvalves are installed at the entrance and atthe major appliances.

Climate Control SystemsIn many homes the climate control sys-

tem is used to heat the building in winterand cool it in summer. This may be donewith a single unit or with separate heatingand cooling units.

With regard to heating systems, roomsin a home can be directly or indirectlyheated. In a direct heating system, the fuelis used in the room to be heated. Directheating may use a stove or a fireplace thatburns wood or coal. Note, however, thatburning wood or coal can be expensiveand causes considerable air pollution.

Other direct heating methods use elec-trical power. These systems use resistanceheaters that are installed in the walls oralong the baseboards. Also, ceiling radiantwires or panels may supply the heat.

Indirect systems heat a conductionmedium such as air or water. This mediumthen carries the heat to the rooms. Theheat is then given off to the air in the room,


Bathroom

Meter

SinkSinkDishwasherToilet

Cold Water Hot Water Shutoff

Sink

Shower

WasherWater Heater

CurbValve

Kitchen Utility Room

Tub

Figure 17-20. This schematic diagram shows the potable water system for a home. Each fixturehas a shutoff valve.


Figure 17-21. The energy sources for thesesystems are electricity, coal, oil, wood, nat-ural gas, or propane.

Furnaces that heat air as a conductionmedium are called forced-air heating sys-tems. Forced-air furnaces draw air from theroom. This air is heated as it movesthrough the furnace. A fan delivers theheated air through ducts to various rooms.

Hot water heating uses water to carrythe heat. The water is heated in the furnaceand pumped to various rooms. The waterpasses through room-heating units that havemetal fins that surround the water pipe.The fins dissipate the heat into the room.

Some homes are heated with solarenergy. Two types of solar homes exist:active and passive. Passive solar homes useno mechanical means to collect and storeheat from the sun. Active solar homes usepumps or fans to move a liquid or air to col-lect solar heat. After the heat is collected the

liquid or air is moved to a storage device.Solar heating systems are very effective inareas that have ample sunshine.

With regard to cooling systems, manybuildings have cooling systems to cool theair during the warm parts of the year.Cooling systems use compressors, evapo-rators, and condensers much like a refrig-erator. The system has a fan that drawsthe air from the room. The air passes overa cold evaporator. This is similar to aforced-air furnace. Instead of the air beingheated, it is cooled. The cool air is returnedto the room.

Another system used in climate controlis a unit called a heat pump. A heat pumpworks as a cooling and a heating system.A heat pump can be operated in two direc-tions. Operating in one direction the heatpump acts like an air conditioner. The heatpump takes warmth from inside the houseand discharges it outside. In the winter


1. The fuel is used in the furnace to produce heat.

2. The conduction medium (air or water) moves the heat from the furnace.

4. The conduction medium returns to the furnace to be heated again.

3. Heat emitters give off the heat from the medium.

• Gas• Electricity• Wood• Oil

Fuel

Furnace

Figure 17-21. Indirect heating systems heat a conduction medium. The resulting heat is then putinto the air in the room.

the heat pump works in reverse. It takeswarmth from the outside and brings it intothe house. Heat pumps can use air, water,or the ground as a heat source. Heatpumps that use air work best in areas thatdo not get very cold, such as the southernand central United States. Groundwaterheat pumps use well water as the heatsource. The water is pumped from the wellto the heat pump. The water has heatremoved or the water receives excess heat,and then the water returns to the well.Ground coil systems are buried in the soilto take or give off heat. Groundwater andground coil systems can be used in colderclimates. Otherwise, heat pumps need asmall furnace or other auxiliary heat sourceas a backup.

Communication SystemsMost homes have communication sys-

tems such as telephone, radio, and televi-sion. These systems require special wiring.

Telephone wiring and television cables arenormally installed during the construc-tion of the building. Installing them aftera building is finished is costly. It takes con-siderable work to feed the wires throughattics, under floors, and inside walls. Somehomes have intercom systems that allowtwo-way communication between rooms.Many intercom systems allow radio pro-grams to be played throughout the house.

Finishing the Exterior and InteriorThe final exterior finishing step is

installing siding and trim. Siding is the fin-ish covering used on a wood building. Manysiding materials are in use. Wood shinglesand boards, plywood, hardboard, brick,stone, aluminum, vinyl, and stucco are allused as siding. Look back at Figure 17-17.You will see bricks being installed over ply-wood sheathing. Trim is the strips of woodthat cover the joints between window anddoor frames and the siding.


Connections to Technology: Communication

Word OriginsProbably most people would be happy to have their name become part of

everyday language as a result of their invention. John McAdam, a Scottishengineer who experimented with road construction, might be doubly pleased;his work with roads has resulted in two words in common use today.

As described in this chapter, John McAdam developed the crushed stoneroad. This new type of road had three layers of crushed rock compacted into asolid mass. The road was also made slightly convex. McAdam’s designimproved roads tremendously because now the traffic load was spread, andrainwater ran off the surface. We are now more familiar with this type of road-way through the use of the term macadam.

The other word is even more familiar and is also related to roads. In aneffort to improve roads even more, people used tar to bind the crushed rocktogether. This process was given the name tarmacadam or, as we now call itwhen we use it on runways, tarmac.

Modern roads are still built using John McAdam’s principles. Can youfind another common word we use today that is based on someone’s nameand invention?


The interior walls are the next walls tobe finished. Insulation is placed between thestuds and around the windows and doorsof all exterior walls. Insulation reducesheat loss on cold days and heat gain on hotdays. The most common type of insula-tion is fiberglass. It is available in blanketsor batts. A vapor barrier of polyethylenefilm is attached to the studs over the insu-lation. The vapor barrier prevents moisturefrom building up in the insulation.

Once insulation and utilities are in place,the interior wall surfaces can be covered. Themost widely used interior wall covering isgypsum wallboard, commonly known asdrywall. Drywall has replaced plaster inmost applications. Drywall is a sheet mate-rial made of gypsum bonded between lay-ers of paper. The sheets of drywall are nailed

or screwed onto the studs and ceiling joists.The fastener heads and drywall seams arethen covered with a coating called jointcompound. The compound is applied inseveral thin coats. This is done to makesmooth surfaces and joints between thesheets of drywall.

The inside and outside of the houseare now ready for the finishing touches.Interior wood trim is installed around thedoors and windows. Kitchen, bathroom,and utility cabinets are set in place. Floorcoverings such as ceramic tile, wood floor-ing, carpet, or linoleum are installed overthe subflooring. Baseboards are installedaround the perimeter of all the rooms. Theexterior siding and wood trim is painted.Interior trim is painted or stained. Thewalls are painted or covered with wallpa-per or wood paneling. Lighting fixtures,switch and outlet covers, towel racks, andother accessories are installed. The floorsand windows are cleaned. Now the homeis finished and ready to be occupied.

Completing the SiteCompleting the building is the major

part of the project. Other work remains tobe done, however. The site must be fin-ished. Earth is moved to fill in areasaround the foundation. Sidewalks anddriveways are installed.

The yard area needs to be landscaped.Landscaping helps to prevent erosion andimproves the appearance of the site. Trees,shrubs, and grass are planted. Landscapingcan divide the lot into areas for recreationand gardening. Landscaping can be usedto screen areas for privacy, direct foot traf-fic, and shield the home from wind, sun,and storms.

Look at Figure 17-22. The top viewshows dirt being moved onto the site forlandscaping activities. The bottom viewshows a finished landscaped area. Noticehow the trees and lawn improve theappearance. Also, note that a grassy moundis used to guide people onto the sidewalk.


Figure 17-22. This site was finished by grad-ing the lot (top) and planting landscaping(bottom).

Heavy EngineeringStructures

Construction activities do not alwaysproduce buildings. We need and use manyother types of constructed structures. Thesestructures are sometimes called civil struc-tures, or heavy engineering structures.These structures include highways, raillines, canals, pipelines, power transmissionand communication towers, hydroelectricand flood control dams, and airports. Theyprovide the paths for the movement ofwater, people, goods, information, or elec-tric power. Each of these structures is theresult of heavy engineering construction.

These projects can be grouped in vari-ous ways. For this discussion, we willgroup them into transportation, commu-nication, and production structures.

Transportation StructuresTransportation systems depend on con-

structed structures. These structuresinclude railroad lines, highways andstreets, waterways, and airport runways.Other constructed works help vehiclescross uneven terrain and rivers. Thesestructures include bridges and tunnels.Pipelines are land transportation struc-tures that are used to move liquids or gasesover long distances.

Let us look at some examples of theseconstructed works. We will discuss road-ways and bridges.

RoadwaysRoads are almost as old as civilization.

People first used trails and paths to travel.Later, they developed more extensive roadsystems. The Romans built the first engi-neered roads more than two thousandyears ago. Their influence remained untilthe 1700s, when modern road buildingstarted. Today’s roads have their roots inthe work of the Scottish engineer JohnMcAdam. He developed the crushed stoneroad. His roads were built of three layers

of crushed rock that was laid in a ribbonabout 10” (25 cm) thick. Later, this roadbedwas covered with an asphalt-gravel mix.Asphalt roads are very common today. A more recent development is the con-crete roadway.

Building a road starts with selectingand surveying the route. Next, the route iscleared of obstacles such as trees, rocks, andbrush. The roadway is graded so that it willdrain. Drainage is important to preventroad damage from freezing and thawing.Also, a dry roadbed withstands heavy traf-fic better than a wet, marshy one. Anotherreason for grading is to keep the road’sslope gentle. Elevation changes aredescribed using the term grade. Grades areexpressed in percentages. A road with a 5percent grade would gain or lose 5’ ofheight for every 100’ of distance. Mostgrades are kept below 7 percent.

Once the roadbed is established, thelayers of the road are built, Figure 17-23.The graded dirt is compacted, and a layerof coarse gravel is laid. This is followedwith finer gravel that is leveled and com-pacted. Next, the concrete or asphalt toplayer is applied. Concrete roads are laid inone layer. Asphalt is generally applied intwo layers: a coarse undercoat and a finertopcoat. Finally, the shoulders or edges ofthe road are prepared. The shoulders canbe gravel or asphalt.

BridgesAnother constructed structure vital for

transportation is the bridge. Bridges pro-vide a path for vehicles to move overobstacles. These obstacles include marshyareas, ravines, other roads, or bodies ofwater. Bridges can carry a number of trans-portation systems. These systems includehighways, railroads, canals, pipelines, andfootpaths.

Generally there are two types of bridges:fixed and movable. A fixed bridge does notmove. Once the bridge is set in place itstays there. Movable bridges can change



their position to accommodate traffic belowit. This type of bridge is used to span shipchannels and rivers. The bridge is drawnup or swung out of the way so that shipscan pass.

Bridges have two parts, Figure 17-24.The substructure spreads the load of thebridge to the soil. The abutments and thepiers are parts of the substructure. Thesuperstructure carries the loads of the deckto the substructure. The deck is the partused for the movement of vehicles andpeople across the bridge.

The kind of superstructure a bridgehas indicates the type of bridge. The types

of bridges are beam, truss, arch, cantilever,and suspension, Figure 17-25.

Beam bridges use concrete or steelbeams to support the deck. This type ofbridge is widely used when one roadcrosses another one. Beam bridges are verycommon on the interstate highway system.

Truss bridges use small parts arrangedin triangles to support the deck. Thesebridges can carry heavier loads over longerspans than beam bridges. Many railroadbridges are truss bridges.

Arch bridges use curved members tosupport the deck. The arch may be aboveor below the deck. Arch bridges are used


Grade the Right-of-Way

Building aConcrete Highway

Lay the Base Set the Forms

Ready for Use Place the Shoulders Place the Concrete

Mix the Concrete

Concrete

Shoulder

Fine Gravel

Coarse Gravel

Earth

Figure 17-23. Road building is a step-by-step process.

for longer spans. One of the longest archbridges spans more than 1650’ (502 m).

Cantilever bridges use trusses thatextend out like arms. The ends of the armscan carry small span or hook up to eachother. The load is transmitted by the armsto the center. None of the load is carried bythe ends of the arms.

Suspension bridges use cables to carrythe loads. A large cable is suspended fromtowers. From the large cable, smaller cablesdrop down to support the deck. Suspensionbridges can span distances as great as 4000’(1220 m) and longer.

Communication StructuresMost telecommunication technology

relies on constructed towers to supportantennas. These towers are usually placedon a concrete foundation. A steel tower isbuilt on top of the foundation. Once thetower is complete the signal wiring can be

installed. Similar techniques are used toconstruct towers for power transmissionlines, Figure 17-26.

Production StructuresSome structures that are used for pro-

duction activities are not buildings. Forexample, petroleum refineries are a mix ofmachinery and pipelines. Irrigation sys-tems are constructed to bring water tofarms in dry areas. Evaporation basins arebuilt to recover salt and other mineralsfrom seawater.

Another important production structureis the dam. Dams are used for controllingfloods, supplying water, making recre-ational lakes, or generating electricity.


Abutment Pier

Span

Water

Earth Piles

Deck

Figure 17-24. This diagram shows the partsof a bridge. An arch bridge is shown in thephoto. (American Electric Power Co.)

Truss

Cantilever

Suspension

Arch

Figure 17-25. Four of the five types of bridgesare the truss, the cantilever, the suspension,and the arch. The fifth is the beam bridge.


Several types of dams exist. One type iscalled a gravity dam. Its lakeside is verti-cal whereas the other side slopes outward.The sheer weight of the concrete the damis made from holds the water back. Thedam on the left in Figure 17-27 is a grav-ity dam.

Two more types of dams are the rockdam and the earth dam. The earth dam isalso shown in Figure 17-27. A rock damlooks like two gravity dams placed back-to-back. Both sides slope outward. Rockand earth dams must be covered with awaterproof material to prevent seepage.Clay is often used for this covering.

A buttress dam uses its structure tohold back the water. This type of dam is notsolid. It uses walls of concrete to supporta concrete slab or arches against the water.

Tall dams that hold back large quanti-ties of water are called arched dams. Thearched shape increases the strength of thedam. The arched shape also spreads thepressure onto the walls of the canyonwhere the dam is built.


Figure 17-26. This helicopter is helping toconstruct a tower for an electricity transmis-sion line. (American Electric Power Co.)

Water Level

SolidConcrete

Dam

ReservoirBottom

Earth FilledDam with

Clay Coating

Figure 17-27. The drawing shows two common types of dams. The photo shows a gravity dam.(American Electric Power Co.).


SummaryConstruction is a vital production activity. Construction provides us

with homes, offices, factories, highways, railroads, pipelines, bridges, dams,and other structures. Construction can be divided into two kinds of projects:those that produce buildings and those that produce heavy engineeringstructures.

Most buildings are constructed using the same steps. The site is clearedand prepared for construction. The foundation for the structure is set. Then,the framework or superstructure is erected. Utilities are installed, and the struc-ture is enclosed. The building is finished, and the site is landscaped

The construction of heavy engineering structures varies according to type.We can group these kinds of projects into three categories: transportation struc-tures, communication structures, and production structures.

Key Termsarch bridgesbeam bridgesbuildingsbuttress damcantilever bridgesceilingceiling joistscommercial buildingsconstructiondrywallfasciafloor joistsforced-air heatinggravity damheadersheat pumpheavy engineering constructionheavy engineering structureshot water heatingindustrial buildingslandscaping

lumbermanufactured homepile foundationspotable waterraftersreinforced concreteresidential buildingssheathingsillslab foundationssoffitsole platespread foundationssteelstudssubfloorsuspension bridgestop platetrusstruss bridgeswastewater



Test Your KnowledgeWrite your answers on a separate piece of paper. Please do not write in this book.

1. List the two kinds of constructed works.

2. True or false? A condominium is a residential structure that is generallyowned by the people living in it.

For Questions 3–15, match the construction step on the right to the correct descrip-tion on the left. (Note: Some letters will be used more than once.)

16. True or false? You should use spread foundations on wet or sandy soils.

17. The two types of floors in single-family homes are concrete slab or _____.

18. What is a fascia board used for?

19. The two types of water systems that are part of a plumbing system arecalled _____ and _____ systems.

20. The most common type of insulation is _____.

21. A home built in a factory is called a(n) _____.

22. What does the term grade mean as used in this chapter?

23. True or false? Most railway bridges are beam bridges.

24. True or false? With cantilever bridges, none of the load is carried by theend of the arms.

25. Tall dams that hold back large quantities of water are called _____ dams.

Description

3. _____ Sheathing the walls

4. _____ Putting up drywall

5. _____ Grading

6. _____ Putting in footings

7. _____ Landscaping

8. _____ Putting in heat pump

9. _____ Installing a subfloor

10. _____ Installing the roof

11. _____ Driving in piles

12. _____ Marking the building site

13. _____ Placing floor joists

14. _____ Adding baseboards

15. _____ Installing sidewalk

Construction Step

a. Preparing the site

b. Setting foundations

c. Building the framework

d. Enclosing the structure

e. Installing utilities

f. Finishing interior and exterior

g. Completing the site


Applying Your Knowledge1. Use a chart like the one below to list and describe a few of the con-

structed structures you see as you travel from your home to school.

2. Select one structure that you saw in completing the previous assign-ment. Make a drawing or model of the structure and label the majorparts.

Structure Type of Description–UseConstruction



Modular ActivityThis activity develops the skills used in TSA’s Structural Engineering event.

Structural Engineering

Activity OverviewIn this activity, you will create a balsa-wood bridge and determine its failure weight(load at which the bridge breaks).

Materials� Grid paper

� 20′ of 1/8″ x 1/8″ balsa wood0

� 3″ x 5″ note card

� Glue

Background InformationGeneral. There are several types of bridges: beam, truss, cantilever, sus-pension, and cable-stayed. The type of bridge used in a particular situation isgenerally determined by the length of the span and available materials. For thisactivity, a truss design is considered the most efficient.

Truss bridges. The truss bridge design is based on the assumption that thestructural members carry loads along their axes in compression or tension.Themembers along the bottom of the bridge carry a tensile load.The members alongthe top of the truss carry a compressive load.The members connecting the topand bottom chords (members) can be in tension or compression.

Gussets. Gussets are plates connected to members at joints to add strength.Gussets are normally used in steel construction. The structural steel membersare welded or bolted to the gusset. When designing your bridge, include a gus-set at each joint, if possible.

Wood properties. Due to its molecular structure, wood can normally carry alarger load in tension than it can in compression. Also, a shorter member cancarry a greater compressive load than a longer member.

®

343Chapter 17 Constructing Structures

Guidelines� You must create a scale sketch of the bridge before building.

� Two pieces of balsa wood can be glued together along lengthwise surfaces. Nomore than two pieces of balsa can be glued together.You cannot use an exces-sive amount of glue.

� Gussets cut from the 3″ x 5″ card can be no larger than the diameter of a U.S.quarter coin. A gusset cannot touch another gusset. A gusset cannot be “sand-wiched” between two pieces of balsa wood.

� The bridge design must take into account the loading device. Your teacher willprovide specific guidelines for bridge length, width, and required details for attach-ment of a loading device.

� Your bridge will be weighed before being loaded.

Evaluation CriteriaYour project will be evaluated using the following criteria:

� Accuracy of sketch compared to completed bridge

� Conformance to guidelines

� Efficiency (failure weight ÷ bridge weight)


chapter 17: constructing structures - g-w.com · chapter 17 constructing structures learning...

Documents