The residential construction company I'm with here in Aggieland (Whoop!) builds bunches of houses every year. From first time home buyer products to upscale 3000 sf products. Based on my 11 years of doing residential construction estimating I'll offer the following:
1.) All construction costs are regional, yours may differ from mine.
2.) What does his $100.00 per sf include? You need a scope of work. For all I know the price may include a $20,000.00 septic system and Pella windows. You need a well defined "scope of work" so you know just what your getting.
3.) Are all permits and permitting fees included?
4.) When he is talking price per square foot, you need to establish which sf number he is using. Is it heated sf, slab sf, or another combination of the two.
With these points established I will offer the following opinion.
We have a cost that we call "sticks & bricks". This is a cost that is established as if you were building the structure in space. It would not include lot costs, tap or permit fees, overhead, profits, insurance, or anything other than the material and labor to build the house. This assumption would include a poured in place concrete slab, grades 2 & 3 pine lumber, Hardi-Plank siding, 20 year composition roof, 1/2" sheetrock, plumbing, HVAC, electrical, insulation, cabinets, carpet, etc for a finished ready to occupy house all built to Southern Building Code.
In our area, I would use the dollar amount of about $50.00 for this. Your "sticks & bricks" costs here for a 1200 heated sf house with 2 car attached garage would be around $60,000.00. We use this number for a seat of the pants guesstimate of costs so one can quickly decide if a project is grossly over or underpriced. Real cost varies to either side of this number but is good benchmark for quick costs analysts.
You would then start adding to this number, fee costs, profits, overhead, lot cost, upgrades, etc to get your final project cost.
I hope this is a helpful tool for answering your question.
With best regards.
