F-F-11

Applying Lean to Factory Applying Lean to Factory HomebuildingHomebuilding

Dr. Mike Mullens, PEDr. Mike Mullens, PE

F-F-22

Big Product with Many Large Big Product with Many Large ComponentsComponents

F-F-33

Few Small, Fixed WorkstationsFew Small, Fixed Workstations

F-F-44

Few Large, Fixed WorkstationsFew Large, Fixed Workstations

F-F-55

Many Large, Moving Many Large, Moving WorkstationsWorkstations

Labor and materials flow to Labor and materials flow to product while product flows product while product flows continuously on linecontinuously on line

Little inventory Little inventory because there is because there is no spaceno space

Line used to set Line used to set pace and facilitate pace and facilitate delivery of large delivery of large componentscomponents

F-F-66

Activity Location FlexibilityActivity Location Flexibility

Most operations after roof set can and do take Most operations after roof set can and do take place anywhere on line – as long as place anywhere on line – as long as precedence's are metprecedence's are met

F-F-77

Some Activities Can Stop the Some Activities Can Stop the LineLine

F-F-88

Value Added Value Added Continuously: Continuously: Often in Often in Parallel Parallel ActivitiesActivities

F-F-99

Massive Work ContentMassive Work Content

Multi-operator teams perform trade-focused Multi-operator teams perform trade-focused activitiesactivities

F-F-1010

Massive Work ContentMassive Work Content

Extended cycle timesExtended cycle times

Very difficult to measure work content and cycle Very difficult to measure work content and cycle time for any unittime for any unit

ModuleModule Wall LengthWall Length Wall Assembly Labor: Observed Man MinutesWall Assembly Labor: Observed Man Minutes Estimated Cycle Estimated Cycle Time (Min)Time (Min)

(Feet)(Feet) Value AddedValue Added Non Value Non Value AddedAdded

TotalTotal

2528 A2528 A 8585 252 (89%)252 (89%) 27 (11%)27 (11%) 252 (100%)252 (100%) 126126

2528 B2528 B 8989 294 (84%)294 (84%) 54 (16%)54 (16%) 348 (100%)348 (100%) 174174

Sub TotalSub Total 174174 519 (87%)519 (87%) 81 (13%)81 (13%) 600 (100%)600 (100%) 300300

2632 A2632 A 8383 264 (85%)264 (85%) 48 (15%)48 (15%) 312 (100%)312 (100%) 156156

2632 B2632 B 8080 348 (83%)348 (83%) 72 (17%)72 (17%) 420 (100%)420 (100%) 210210

Sub TotalSub Total 163163 612 (84%)612 (84%) 120 (16%)120 (16%) 732 (100%)732 (100%) 366366

TotalTotal 337337 1131 (85%)1131 (85%) 201 (15%)201 (15%) 1332 (100%)1332 (100%) 666666

F-F-1111

Product Built-to-Order: Varied Product Mix with Customization

F-F-1212

Product Built-to-Order: Varied Product Mix with Customization

F-F-1313

Product Built-to-Order: Varied Product Mix with Customization

F-F-1414

Product Built-to-Order: Varied Product Mix with Customization

F-F-1515

Product Built-to-Order: Varied Product Mix with Customization

F-F-1616

Product Built-to-Order: Varied Product Mix with Customization

F-F-1717

Product Built-to-Order: Varied Product Mix with Customization

F-F-1818

Product Built-to-Order: Varied Product Built-to-Order: Varied Product Mix with CustomizationProduct Mix with Customization

High process variability High process variability

F-F-1919

ModuleModule Wall Wall Length Length (Feet)(Feet)

Wall Assembly Labor: Observed Man Wall Assembly Labor: Observed Man MinutesMinutes

Estimated Estimated Cycle Time Cycle Time (Min)(Min)

Value AddedValue Added Non Value Non Value AddedAdded

TotalTotal

2528 A2528 A 8585 252 (89%)252 (89%) 27 (11%)27 (11%) 252 (100%)252 (100%) 126126

2528 B2528 B 8989 294 (84%)294 (84%) 54 (16%)54 (16%) 348 (100%)348 (100%) 174174

Sub TotalSub Total 174174 519 (87%)519 (87%) 81 (13%)81 (13%) 600 (100%)600 (100%) 300300

2632 A2632 A 8383 264 (85%)264 (85%) 48 (15%)48 (15%) 312 (100%)312 (100%) 156156

2632 B2632 B 8080 348 (83%)348 (83%) 72 (17%)72 (17%) 420 (100%)420 (100%) 210210

Sub TotalSub Total 163163 612 (84%)612 (84%) 120 (16%)120 (16%) 732 (100%)732 (100%) 366366

TotalTotal 337337 1131 (85%)1131 (85%) 201 (15%)201 (15%) 1332 (100%)1332 (100%) 666666

Product Built-to-Order: Varied Product Mix with Customization

High cycle time High cycle time variabilityvariabilityVery difficult to Very difficult to predict work predict work content and content and cycle time for cycle time for each activityeach activityNot easy to Not easy to control control line balanceline balance

F-F-2020

Cycle vs. TAKT TimeCycle vs. TAKT Time

Average cycle time for each activity must be less Average cycle time for each activity must be less than TAKT timethan TAKT time

Activity with largest average cycle time is Activity with largest average cycle time is bottleneck activity bottleneck activity

If bottleneck activity is delayed, line capacity is If bottleneck activity is delayed, line capacity is lost – can happen even if average cycle less lost – can happen even if average cycle less than TAKT timethan TAKT time

F-F-2121

Seeing the Waste (and the Seeing the Waste (and the Opportunity)Opportunity)

Constant imbalance in labor & work contentConstant imbalance in labor & work content

Production mistakesProduction mistakes

Design oversightsDesign oversights

Material Material shortages shortages

Materials45-50%

Labor10-15%

Overhead35-45%

F-F-2222

Floating Bottlenecks: Imbalance in Floating Bottlenecks: Imbalance in Labor and Work Content Labor and Work Content

Upstream Queue - FloorsUpstream Queue - Floors

F-F-2323

Floating Bottlenecks: Imbalance in Floating Bottlenecks: Imbalance in Labor and Work Content Labor and Work Content

Downstream line starvation – drywall finishing Downstream line starvation – drywall finishing and interior finishingand interior finishing

F-F-2424

Floating Bottlenecks: Imbalance in Floating Bottlenecks: Imbalance in Labor and Work Content Labor and Work Content

Other Impacts:Other Impacts:– Hurry Hurry exhaustion, frustration, rework exhaustion, frustration, rework

– Overtime Overtime higher costs, turnover higher costs, turnover

– Unfinished work in yardUnfinished work in yard

– Lost production capacityLost production capacity

F-F-2525

Value-Added vs. Non-Value Added Value-Added vs. Non-Value Added TimeTime

ModuleModule Wall Wall LengthLength

Observed Man MinutesObserved Man Minutes Estimated Man Estimated Man MinMin

(Feet)(Feet) Value AddedValue Added Non Value Non Value AddedAdded

TotalTotal

2528 A2528 A 8585 252 (89%)252 (89%) 27 (11%)27 (11%) 252 (100%)252 (100%) 358 (142%)358 (142%)

2528 B2528 B 8989 294 (84%)294 (84%) 54 (16%)54 (16%) 348 (100%)348 (100%) 371 (106%)371 (106%)

Sub TotalSub Total 174174 519 (87%)519 (87%) 81 (13%)81 (13%) 600 (100%)600 (100%) 729 (122%)729 (122%)

2632 A2632 A 8383 264 (85%)264 (85%) 48 (15%)48 (15%) 312 (100%)312 (100%) 349 (112%)349 (112%)

2632 B2632 B 8080 348 (83%)348 (83%) 72 (17%)72 (17%) 420 (100%)420 (100%) 337 (80%)337 (80%)

Sub TotalSub Total 163163 612 (84%)612 (84%) 120 (16%)120 (16%) 732 (100%)732 (100%) 686 (94%)686 (94%)

TotalTotal 337337 1131 (85%)1131 (85%) 201 (15%)201 (15%) 1332 (100%)1332 (100%) 1415 (106%)1415 (106%)

F-F-2626

Operations Process Chart with Operations Process Chart with Work MeasurementWork Measurement

100282.7348.2263.5294225Total

618.020172312Remove wall/walls from jig using crane18

13.06006Put plastic cover on wall if needed using stapler17

25.26.75554Remove screws that have missed studs or subassemblies using screwdriver

16

616.72420149Screwing sheetrock/firewall to wall using electrical screwdriver

15

1439.048444024Attach sheetrock/firewall to wall with nails14

411.2191268Put glue on studs and subassemblies13

11.50033Staple foil tape if required by state law using stapler

12

13.04332Puts nails on mark from string using hammer11

25.256.53.565Make horizontal mark with string for sheetrock/firewall placement

10

513.016121212Square wall9

1131.235303426Measure and cut sheetrock and/or firewall where needed

8

926.533232525Nail top plate/plates to studs and subassemblies using nailgun

7

926.033243017Nail bottom plate to studs and subassemblies using nailgun

6

1029.537233127Place subassemblies and/or studs on bottom plate5

26.810575Cut length of top and bottom plate4

925.736242221Measure length of top and bottom plate, and mark on bottom plate where to place subassemblies

3

411.51412812Place top and bottom plates on jig2

39.506257Review drawing. Decide what walls to build.1

% age2632 B2632 A2528 B2528 ASequence

Avg. Man MinMAN MINTaskTask

100282.7348.2263.5294225Total

618.020172312Remove wall/walls from jig using crane18

13.06006Put plastic cover on wall if needed using stapler17

25.26.75554Remove screws that have missed studs or subassemblies using screwdriver

16

616.72420149Screwing sheetrock/firewall to wall using electrical screwdriver

15

1439.048444024Attach sheetrock/firewall to wall with nails14

411.2191268Put glue on studs and subassemblies13

11.50033Staple foil tape if required by state law using stapler

12

13.04332Puts nails on mark from string using hammer11

25.256.53.565Make horizontal mark with string for sheetrock/firewall placement

10

513.016121212Square wall9

1131.235303426Measure and cut sheetrock and/or firewall where needed

8

926.533232525Nail top plate/plates to studs and subassemblies using nailgun

7

926.033243017Nail bottom plate to studs and subassemblies using nailgun

6

1029.537233127Place subassemblies and/or studs on bottom plate5

26.810575Cut length of top and bottom plate4

925.736242221Measure length of top and bottom plate, and mark on bottom plate where to place subassemblies

3

411.51412812Place top and bottom plates on jig2

39.506257Review drawing. Decide what walls to build.1

% age2632 B2632 A2528 B2528 ASequence

Avg. Man MinMAN MINTaskTask

F-F-2727

Non-Value Added ActivitiesNon-Value Added ActivitiesTaskTask MAN MINMAN MIN Tot. Man MinTot. Man Min

2528 A2528 A 2528 B2528 B 2632 A2632 A 2632 B2632 B %%

UnknownUnknown 1212 2020 22.522.5 11.7511.75 66.2566.25 3434

Rebuild window subassemblyRebuild window subassembly 2424 2424 1212

Cut sheetrock for other workstationCut sheetrock for other workstation 2222 2222 1111

Helping roof jigHelping roof jig 22 1717 1919 1010

Paper workPaper work 1717 1717 99

Out of nails and glueOut of nails and glue 1212 1212 66

Move modules on-lineMove modules on-line 88 88 44

Helping wall setHelping wall set 33 44 77 44

Worker hurt by nailgunWorker hurt by nailgun 77 77 44

Order sheetrockOrder sheetrock 77 77 44

Clean-upClean-up 44 44 22

Moving pile of sheetrockMoving pile of sheetrock 22 22 11

Carry bathtub to wall set areaCarry bathtub to wall set area 22 22 11

Total:Total: 2323 5454 48.548.5 7171 197197 100100

F-F-2828

House No. 2 5 8 11 14 17 20 23 26 29 2 5 8 11 14 17 20 23 26 29 1 4 7 10 13 16 19 22 25 28 1 4 7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 23

2201 12204 022242256 42258 118712212 4 22220 32230 722382254 322232267 12231213622502262223622392264 # 2 0221922402233219322702274 022602275228122152280225122762192 #226322792277228322892297230022982290 22293 112299

February

Production Cycle Times

841902

September October November December

8842

333

January

1526

54734

478516

686450 34

866471

517

474605

853438

902231

776 94

441 22

478 16471

298

5734

643555 5

53499

51570 85

475495

438 52

1149 91

766 69

211147

460 39 18 14

30402

328338 346

5

515

489853

410

12

22

136182

317577

Production ScheduleProduction Schedule

F-F-2929

Distribution of Production Cycle Times

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Duration per House (Weeks)

Nu

mb

er o

f H

ou

ses

Avg. 8 weeks

Production Cycle TimesProduction Cycle Times

F-F-3030

ReworkRework

Rework

0 5 10 15 20 25

Shop II

Deck Jig

Wall Jig

Wall Set

Roof Table

Roof Set

Rough Electric

Rough Plumbing

Sheetrock

Sheathing

Roofing

Doors & Windows

Siding

Taping

Sand & Paint

Finish Electric

Door Shop

Trim

Cabinets

Countertops

Painting

Finish Floater

Quality Control

Clean-up

Shop III

Acti

vit

y

% of Total Hours Worked

44%

Avg. = 7%

F-F-3131

ReworkRework

Labor wasteLabor waste

Service problemsService problems

Line variabilityLine variability

F-F-3232

ReworkRework

F-F-3333

Lean Construction PrinciplesLean Construction Principles

Keep activities flowing, particularly along critical Keep activities flowing, particularly along critical path and bottleneck activitiespath and bottleneck activities

Remove uncertainty and variability, especially Remove uncertainty and variability, especially along critical path and bottleneck activitiesalong critical path and bottleneck activities

F-F-3434

Lean Construction ApproachLean Construction Approach

Improve quality of task assignmentsImprove quality of task assignments

Be sure preceding activities are complete, task Be sure preceding activities are complete, task well documented, and materials and tools are well documented, and materials and tools are availableavailable

F-F-3535

Lean Construction Problem Lean Construction Problem MitigationMitigation

Plan buffers – backlog of activities for crews Plan buffers – backlog of activities for crews (queues of work ready to be done – adding to (queues of work ready to be done – adding to length of critical path and thus to production line)length of critical path and thus to production line)

Surge piles – raw and WIP materialsSurge piles – raw and WIP materials

Flexible capacity – intentionally underutilized Flexible capacity – intentionally underutilized crews or flexible use of cross-trained workerscrews or flexible use of cross-trained workers