Final cost per square foot:
using exterior dimensions for 1200 sq. ft., cost was $37 sq. ft.
Without the porch expenses, using interior living space of 995 sq. ft., cost was $45 sq. ft.
Porch costs were $7,000 for 925 sq. ft. of covered porch, or $7.50 sq ft.
(Some headings are linked to details)

Here is a page with some other resources to help you

Item Actual Cost Hours of Labor Percent of work hired out
Plans $1,050 many hours of planning 100%
Tools $1,900 -- --
Consultation
$5,000
-- 
-- 
Permits $3,500 -- --
Septic $1,500 none 100%
Foundation & Stemwall $5,500 235 25%
Floors $600 131 0%
Bales,Walls & Plasters $4,800 970 0%
Trusses and Roof  $5,200 188  25%
Plumbing & Fixtures $3,000 107 0%
Electric & Appliances $4,500 133 20%
Misc. Materials $2,000 -- --
Windows/Doors  $3,000 97 25%
Loft and Stairway
$3,000
110
50%
Porch $7,000 155 85%
Cabinets $300 15 0%
Grand Total
$51,450
2,041
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