The intent of this research is to empower and equip Hawai’i homeowners with the ability to generate a conceptual ADU scheme with the assistance of an ADU Decision Support System. This support system promotes a design path to get from intent to preliminary production design. The ADU Decision Support System encourages homeowners to research options towards the construction of an ADU before financially committing to the process. Through the process of creating a preliminary production design, The ADU Decision Support System educates the homeowners on the design and budget planning required to construct and ADU in the homeowners’ spare time and without financial obligation. The information gained through the ADU Decision Support System allows homeowners clearly decide whether to pursue ADU construction. The process also prepares the homeowner for communicating with licensed professionals like architects
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and contractors saving the homeowner time and money.
Figure 11.1 - Final detached example design in relation to the existing site
Figure 11.2 - Final attached modified example design in relation to the existing site
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DETACHED ADU COST ANALYSIS
Table 11.1 – Cost analysis of example detached design
ADU Prototype Material
Cost Estimate Type: Detached
Family Type/Material Installation
Casework Schedule
Counter Top 117.00 LF $9.10 $11.10 $2,363.40
Vanity Cabinet Double Door Sink Unit: 30" 1.00 $305.00 EA $31.00 $336.00
Vanity Cabinet Double Door Sink Unit: 36" 1.00 $345.00 EA $33.00 $378.00
Base Cabinet Single Door & Drawer: 18" 3.00 $259.00 EA $28.50 $862.50
Subtotal: $3,939.90 Ceiling
Plaster Drop Ceiling
2 coat gyp. Painted on Wooden
Support 68.00 SF $1.48 /SF $5.10 /SF $447.44
Subtotal: $447.44
Door Schedule
Single-Flush 36" x 84" 2.00 $315.00 EA $183.00 EA $996.00
Sliding Pocket Door (Sub Single-Flush)
32" x84" Sliding Pocket Door (Sub
Hinged) 2.00 $315.00 EA $183.00 EA $630.00
Subtotal: $1,626.00
Floor Material Takeoff
Laminate Flooring Wood Vinyl 277.00 SF $3.30 /SF $0.92 /SF $1,168.94
Tile Flooring Tile 69.00 SF $4.96 /SF $4.51 /SF $653.43
Subtotal: $1,822.37
Lighting and Electrical
Receptacles and Wiring 5 per 1000 SF 344.00 SF $0.55 /SF $1.80 /SF $808.40
Fluorescent Fixtures T-12 5 Fixtures @ 40 344.00 SF $0.81 /SF $1.72 /SF $870.32
Lighting and Branch Wiring 5 per 1000 SF 344.00 SF $0.26 /SF $0.91 /SF $402.48
Subtotal: $1,678.72
Plumbing Fixtures
Kitchen Sink 32" x 21" Double Bowl 1.00 $745.00 EA $785.00 EA $1,530.00
Bathroom Layout
3 Fixture, Two Wall (W.C., Lav,
Shower) 1.00 $3,075.00 EA $2,450.00 EA $5,525.00
$7,055.00
Equipment
Water Heater Electric, 30 Gallon 1.00 $520.00 EA $162.00 $682.00
Range Built-in 1.00 $750.00 EA $97.00 $847.00
Washing Machine Automatic 1.00 $1,125.00 EA $625.00 $1,750.00
Refrigerator Economy 1.00 $490.00 EA $81.50 $571.50
Subtotal: $3,850.50
Roofing
Single Ply Membrane EPDM 485.00 SF $1.14 $0.90 $989.40
Asphalt Roofing Strip Shingles 485.00 SF $0.87 $1.00 $906.95
Insulation 2" Rigid Insulation 348.00 $1.08 $0.51 $553.32
2" x 10" Rafter 16" O.C. 485.00 SF $1.27 /SF $1.62 $1,401.65
Gutter Box, Aluminum 62.70 $2.68 $4.96 $479.03
Downspout Rectangular, Aluminum 8.00 LF $1.14 $3.13 $34.16
Roof Flashing Aluminum 90.58 LF $1.12 $3.25 $395.83
Subtotal: $4,760.34 Foundation
Slab Edge
24" x 12" Cast-in-place,
Reinforced 81.92 LF $14.00 /LF $21.00 $2,867.20
Slab 6" Cast-in-Place, Reinforced 393.00 SF $2.86 /SF $2.93 $2,275.47
Subtotal: $5,142.67 Walls
Exterior Stud Wall 5"
2" x 4" Plain Vinyl Siding, 16" O.C.
Insul. Wall 366.00 SF $2.48 /SF $4.78 $2,657.16
Exterior Stud Wall 5" 1/2" Interior Drywall 366.00 SF $0.31 /SF $0.51 $300.12 Exterior Stud Wall 7"
2" x 6" Plain Vinyl Siding, 16" O.C.
Insul. Wall 180.00 SF $2.90 /SF $4.93 $1,409.40
Exterior Stud Wall 7" 1/2" Interior Drywall 180.00 SF $0.31 /SF $0.51 $147.60 Interior Stud Wall 5"
2" x 4" Wood Studs, 16" O.C. with
blocking 177.00 SF $0.29 /SF $1.03 $233.64
Interior Stud Wall 5" 1/2" Interior Drywall (2 sides) 354.00 SF $0.31 /SF $0.51 $290.28 Interior Stud Wall 7"
2" x 6" Wood Studs, 16" O.C. with
blocking 58.00 SF $0.44 /SF $1.14 $91.64
Interior Stud Wall 7" 1/2" Interior Drywall (2 sides) 116.00 SF $0.31 /SF $0.51 $95.12 Subtotal: $5,224.96
Window Schedule Louver Window (Sub Wood
Double Hung) 36" x 48" (Sub 32" x 54") 7.00 $237.00 EA $224.00 $3,227.00 Louver Window (Sub Wood
Casement) 24" x 36"(Sub 22" x 38") 2.00 $320.00 EA $147.00 $934.00
Fixed Window (Sub Wood
Awning) 31" x 24" (Sub 34" x 21") 1.00 $223.00 EA $112.00 $335.00
Subtotal: $4,496.00
A RS Means Historical Cost Index (2010 - 2015)
Material Cost Per Sq. Ft.
* Estimate not including labor and time
* Estimate not including contingency
* Estimate not including overhead and profit
* Unit prices are for conceptual representation and not representative of real cost (costs refferance RSMeans 2010)
Unit Cost
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ADU Prototype Material
Cost Estimate Type: Detached
Family Type/Material Installation
Casework Schedule
Counter Top 117.00 LF $9.10 $11.10 $2,363.40
Vanity Cabinet Double Door Sink Unit: 30" 1.00 $305.00 EA $31.00 $336.00
Vanity Cabinet Double Door Sink Unit: 36" 1.00 $345.00 EA $33.00 $378.00
Base Cabinet Single Door & Drawer: 18" 3.00 $259.00 EA $28.50 $862.50
Subtotal: $3,939.90 Ceiling
Plaster Drop Ceiling
2 coat gyp. Painted on Wooden
Support 68.00 SF $1.48 /SF $5.10 /SF $447.44
Subtotal: $447.44
Door Schedule
Single-Flush 36" x 84" 2.00 $315.00 EA $183.00 EA $996.00
Sliding Pocket Door (Sub Single-Flush)
32" x84" Sliding Pocket Door (Sub
Hinged) 2.00 $315.00 EA $183.00 EA $630.00
Subtotal: $1,626.00
Floor Material Takeoff
Laminate Flooring Wood Vinyl 277.00 SF $3.30 /SF $0.92 /SF $1,168.94
Tile Flooring Tile 69.00 SF $4.96 /SF $4.51 /SF $653.43
Subtotal: $1,822.37
Lighting and Electrical
Receptacles and Wiring 5 per 1000 SF 344.00 SF $0.55 /SF $1.80 /SF $808.40
Fluorescent Fixtures T-12 5 Fixtures @ 40 344.00 SF $0.81 /SF $1.72 /SF $870.32
Lighting and Branch Wiring 5 per 1000 SF 344.00 SF $0.26 /SF $0.91 /SF $402.48
Subtotal: $1,678.72
Plumbing Fixtures
Kitchen Sink 32" x 21" Double Bowl 1.00 $745.00 EA $785.00 EA $1,530.00
Bathroom Layout
3 Fixture, Two Wall (W.C., Lav,
Shower) 1.00 $3,075.00 EA $2,450.00 EA $5,525.00
$7,055.00
Equipment
Water Heater Electric, 30 Gallon 1.00 $520.00 EA $162.00 $682.00
Range Built-in 1.00 $750.00 EA $97.00 $847.00
Washing Machine Automatic 1.00 $1,125.00 EA $625.00 $1,750.00
Refrigerator Economy 1.00 $490.00 EA $81.50 $571.50
Subtotal: $3,850.50
Roofing
Single Ply Membrane EPDM 485.00 SF $1.14 $0.90 $989.40
Asphalt Roofing Strip Shingles 485.00 SF $0.87 $1.00 $906.95
Insulation 2" Rigid Insulation 348.00 $1.08 $0.51 $553.32
2" x 10" Rafter 16" O.C. 485.00 SF $1.27 /SF $1.62 $1,401.65
Gutter Box, Aluminum 62.70 $2.68 $4.96 $479.03
Downspout Rectangular, Aluminum 8.00 LF $1.14 $3.13 $34.16
Roof Flashing Aluminum 90.58 LF $1.12 $3.25 $395.83
Subtotal: $4,760.34 Foundation
Slab Edge
24" x 12" Cast-in-place,
Reinforced 81.92 LF $14.00 /LF $21.00 $2,867.20
Slab 6" Cast-in-Place, Reinforced 393.00 SF $2.86 /SF $2.93 $2,275.47
Subtotal: $5,142.67 Walls
Exterior Stud Wall 5"
2" x 4" Plain Vinyl Siding, 16" O.C.
Insul. Wall 366.00 SF $2.48 /SF $4.78 $2,657.16
Exterior Stud Wall 5" 1/2" Interior Drywall 366.00 SF $0.31 /SF $0.51 $300.12 Exterior Stud Wall 7"
2" x 6" Plain Vinyl Siding, 16" O.C.
Insul. Wall 180.00 SF $2.90 /SF $4.93 $1,409.40
Exterior Stud Wall 7" 1/2" Interior Drywall 180.00 SF $0.31 /SF $0.51 $147.60 Interior Stud Wall 5"
2" x 4" Wood Studs, 16" O.C. with
blocking 177.00 SF $0.29 /SF $1.03 $233.64
Interior Stud Wall 5" 1/2" Interior Drywall (2 sides) 354.00 SF $0.31 /SF $0.51 $290.28 Interior Stud Wall 7"
2" x 6" Wood Studs, 16" O.C. with
blocking 58.00 SF $0.44 /SF $1.14 $91.64
Interior Stud Wall 7" 1/2" Interior Drywall (2 sides) 116.00 SF $0.31 /SF $0.51 $95.12 Subtotal: $5,224.96
Window Schedule Louver Window (Sub Wood
Double Hung) 36" x 48" (Sub 32" x 54") 7.00 $237.00 EA $224.00 $3,227.00 Louver Window (Sub Wood
Casement) 24" x 36"(Sub 22" x 38") 2.00 $320.00 EA $147.00 $934.00
Fixed Window (Sub Wood
Awning) 31" x 24" (Sub 34" x 21") 1.00 $223.00 EA $112.00 $335.00
Subtotal: $4,496.00
A RS Means Historical Cost Index (2010 - 2015)
Material Cost Per Sq. Ft.
* Estimate not including labor and time
* Estimate not including contingency
* Estimate not including overhead and profit
* Unit prices are for conceptual representation and not representative of real cost (costs refferance RSMeans 2010)
Unit Cost