Cost estimate

I recently submitted a building permit application for a 12′ x 16′ timber frame outbuilding, and after a little back-and-forth over email with the county land use specialist while my application is under review, I was asked to come up with a cost estimate which the county needs to help track development.  Since I will be milling all the timbers and lumber myself, the estimate is significantly higher because it’s based on retail prices for specialty milling.  I came up with an itemized list of materials needed for construction and looked up average prices in my area.  For a little context, the building will be finished using the wrap-and-strap method with pine siding for the interior and exterior, yellow birch (or similar available hardwood) flooring, and metal roofing.  The building will sit on concrete piers and have 6-8 windows, a standard door, and possibly a sliding door.  Some important dimensions are 744 sq ft of wall space, 192 sq ft of floor space (plus an extra 80 sq ft for loft), 360 sq ft of roof space, and 1812.5 bf (board feet) of timbers.  The materials list:

Variable width pine @ $3.00/bf  –  $5540

Timbers (expanded list below) @ $6.00/bf  –  $10,875

Flooring @ $5.00/bf  –  $1,360

Roofing  –  $1,800

2×4 framing materials  –  $1,000

Sliding door  –  $500

Exterior door  –  $300

Windows  –  $1,800

Insulation  –  $1150

Plywood  –  $80

Concrete, rebar, and forms –  $95

TOTAL  –  $24,500

To calculate labor, I used the standard ratio of %30 labor cost to %70 materials cost for residential construction and came up with $10,500.  The grand total amount for the complete rough estimate of the finished building would be $35,000 and that is close to the assessed value I would expect for an insurance appraisal.  It seems like a lot for an outbuilding but I have to keep a few things in mind.  First, my out-of-pocket costs will be much lower, probably closer to $6,500.  Second, the building will last decades longer than a conventional stick frame structure.  Finally, the structure is fully weather-proof and ready to accept plumbing, heating, and electrical upgrades so it’s really much more than a lowly outbuilding.  For anyone interested in a more detailed breakdown of the timber materials, I have added a list below:

Sills 8×8  2-12′, 2-16′ (56′)

Tie beams and plates 7×8  3-12′, 2-18′ (72′)

Posts 7×7  6-12′ (72′)

Joists 5×7  5-12′ (60′)

Loft joists 5×6  5-10′ (50′)

Rafters 5×5  18-10′ (180′)

Wall girts and door posts 4×5  7-8′, 1-12′ (68′)

Collars and braces 3×5  9-10′ (90′)

Also hardwood pins:  12-1″dia and 75-3/4″dia; and wedges:  6-12″ x 6/4″ x 11/4″

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