Plan HG-1304•Backyard ADU / Granny Flat•28' × 24' Footprint

674 Sq Ft (24x28) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan (Consolidated Wet-Wall + Open Great Room)

674 sq ft heated living • 2 Bedrooms, 1 Bath • Free 2D CAD Blueprint (.SVG)

Download Free CAD (.SVG)

Room Dimensions & Zones

28' × 24' Shell

PRIMARY SUITE

160 sq ft

14'-6" × 11'-0"

BEDROOM 2

149 sq ft

13'-6" × 11'-0"

GREAT ROOM & DINING

228 sq ft

17'-6" × 13'-0"

BATH & LAUNDRY

58 sq ft

10'-6" × 5'-6"

KITCHEN & ISLAND

79 sq ft

10'-6" × 7'-6"

Build Cost Estimator

Estimated Cost to Build (28' × 24' Backyard ADU / Granny Flat)

Region:

Shell / Building Kit

$31,000 – $40,000

Framing package, roof trusses & exterior shell for 672 sq ft base.

Owner-Builder

$86,000 – $113,000

Saves ~$39,000 by managing local slab & interior trades.

Turnkey Builder

$125,000 – $152,000

Full general contractor finish including slab, HVAC, kitchen & baths.

Est. Monthly Payment

$719 / mo

$110,800 financed (30-Yr)

Down Payment:20%

Interest Rate:6.75%

Free Vector CAD Blueprint • Plan HG-1304

Download 28' × 24' Backyard ADU / Granny Flat Floor Plan (.SVG)

Scalable 2D architectural vector drawing with exterior and room dimensions, door swings, and fixture layout. Opens in AutoCAD, Illustrator, Inkscape, or any browser.

Material Takeoff & Framing Specifications

Concrete volume (15 yd³), roof surface (~776 sq ft), wall framing & architectural notes

Building Package	Specification	Quantity	Est. Range
Structural Shell & Trusses	28'×24' 2x6 Dimensional Lumber Framing / Panelized SIP Option	672 sq ft shell kit	$31,000 – $40,000
Concrete Slab & Grade Beams	Stem Wall or Monolithic Concrete Slab-on-Grade	15 Cubic Yards (4,000 PSI)	$6,500 – $8,500
Roofing & Underlayment	Architectural Standing-Seam Shed / Low-Slope Gable (3:12 Pitch)	10 Roofing Squares (1,000 sq ft)	$4,200 – $6,800
Closed-Cell Spray Foam / Insulation	3" Closed-Cell Wall & Roof Deck Thermal Envelope (R-21 to R-38)	5,282 Board Feet	$7,131 – $9,772
Windows & Exterior Doors	Low-E Argon Black Architectural Glazing + 36" Fiberglass Entry	5 Windows • 4 Doors	$4,450 – $7,000
HVAC & Multi-Zone Mini-Split	High-SEER2 Heat Pump / Ductless Mini-Split System	1.5 Ton (18,000 BTU/hr)	$3,900 – $6,150

Exterior Perimeter

104 Linear Ft

Interior Partitions

~82 Linear Ft

Est. Concrete Slab

15 Cubic Yards

Roof Deck Area

~776 Sq Ft

Plan HG-1304 (674 Sq Ft (24x28) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan (Consolidated Wet-Wall + Open Great Room)) is an IRC R304/R310-vetted backyard adu / granny flat blueprint engineered around a 28'-0" × 24'-0" structural grid (672 sq ft base footprint, 0.86:1 Square-Bay Proportion). Configured on the Consolidated Wet-Wall + Open Great Room topology, this layout delivers 674 sq ft of conditioned residential living area and 105 sq ft of covered outdoor porch deck.

Inside the conditioned envelope, the floor plan is organized into 5 distinct architectural zones: PRIMARY SUITE (14'-6" × 11'-0", 160 sq ft), BEDROOM 2 (13'-6" × 11'-0", 149 sq ft), GREAT ROOM & DINING (17'-6" × 13'-0", 228 sq ft), BATH & LAUNDRY (10'-6" × 5'-6", 58 sq ft), KITCHEN & ISLAND (10'-6" × 7'-6", 79 sq ft). Plumbing rough-ins are consolidated across BATH & LAUNDRY, KITCHEN & ISLAND to minimize sub-slab trenching and manifold pipe runs. Sleeping quarters (PRIMARY SUITE at 160 sq ft; BEDROOM 2 at 149 sq ft) are acoustically buffered from the primary living core and positioned on exterior elevations for code-compliant egress glazing.

From a builder takeoff standpoint, the 28' clear-span width utilizes 2x6 dimensional lumber framing / panelized sip option bearing on 104 linear feet of 6" exterior wall framing (~124 framing studs/posts) and 82 linear feet of interior partitions. The 3:12 architectural standing-seam shed / low-slope gable requires approximately 776 sq ft of roofing material (10 roofing squares), while the stem wall or monolithic concrete slab-on-grade pours at an estimated 15 cubic yards of 4,000-PSI concrete.

Frequently Asked Questions • Plan HG-1304

Building costs, foundation specs, egress & CAD customization questions

How much does it cost to build the 28x24 674 Sq Ft (24x28) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan (Consolidated Wet-Wall + Open Great Room) (HG-1304)?

Based on current national residential construction data for backyard adu / granny flat structures, the dried-in structural shell for Plan HG-1304 (672 sq ft base footprint) ranges from $31,000 to $40,000 ($48/sq ft baseline). A complete turnkey build—including the 15-yard concrete foundation, 82 linear feet of interior framing, MEP rough-ins for 1 bath(s), and interior finishes across 674 sq ft of heated space—ranges from $125,000 to $152,000. Use the interactive Regional Cost Multiplier on this page to adjust for your local labor market and owner-builder sweat equity.

What are the exact room dimensions inside this 674 sq ft 2-bedroom layout?

Plan HG-1304 features 5 architecturally solved spaces inside its 28' × 24' footprint: PRIMARY SUITE (14'-6" × 11'-0", 160 sq ft), BEDROOM 2 (13'-6" × 11'-0", 149 sq ft), GREAT ROOM & DINING (17'-6" × 13'-0", 228 sq ft), BATH & LAUNDRY (10'-6" × 5'-6", 58 sq ft), KITCHEN & ISLAND (10'-6" × 7'-6", 79 sq ft). Every habitable room meets or exceeds IRC R304 minimum area (70+ sq ft) and minimum horizontal dimension (7'-0"+) requirements.

Can this 28' × 24' floor plan be built with post-frame, red-iron steel, or 2x6 stick framing?

Yes. Because the outer envelope is engineered on an even 28'-0" × 24'-0" structural grid (104 LF perimeter) with clear-span 3:12 trusses, a local structural engineer or building kit supplier can adapt the blueprint for 2x6 Dimensional Lumber Framing / Panelized SIP Option, conventional 2x6 stick framing at 16" o.c., laminated post-frame columns at 8' o.c., or structural insulated panels (SIPs).

What files are included in the free CAD blueprint download for Plan HG-1304?

Downloading Plan HG-1304 provides the high-resolution scalable vector floor plan (.SVG) with crisp architectural lineweights, exterior dimension strings (28'-0" × 24'-0"), room-by-room callouts, door swing arcs, and window schedules, plus instant browser printing for contractor bidding and preliminary municipal zoning review.