ChatGPT4 to Estimate Construction Costs
ChatGPT4 Input: James Hardie Artisan V Groove Siding (luxury siding) - the Coverage area of each piece of siding is = 8.25 inches x 144 inches, and it costs $45.70 per piece. How much does it cost per ft, assuming 9.5% California tax rate on materials and the sub-subcontractor charges $5 per ft for install? Assume 10% waste.
Output: To calculate the cost per square foot for James Hardie Artisan V Groove Siding, including 9.5% CA tax, 10% waste, and $5/ft for installation:
Calculate total cost per piece: $45.70 * 1.095 = $50.0415
Calculate cost per sq. ft: $50.0415 / 8.25 sq. ft = $6.0632
Adjust for waste: $6.0632 * 1.1 = $6.6695
Add installation cost: $6.6695 + $5 = $11.6695
The total cost per square foot is approximately $11.67.
Input: if the building is 36ft wide by 56 ft long, and is 10ft high, how much surface area is that? What is the square footage of the building? and how much is the total price per square ft of the building, not surface area?
To calculate the surface area of the walls, we'll consider the two pairs of opposite walls:
Two walls 36 ft wide and 10 ft high: Surface area = 2 * (Width x Height) = 2 * (36 ft x 10 ft) = 720 sq ft
Two walls 56 ft long and 10 ft high: Surface area = 2 * (Length x Height) = 2 * (56 ft x 10 ft) = 1120 sq ft
Total surface area of the walls = 720 sq ft + 1120 sq ft = 1840 sq ft
To calculate the square footage of the building (assuming it's a one-story building), multiply the width by the length:
Square footage = Width x Length = 36 ft x 56 ft = 2016 sq ft
To calculate the total price per square foot of the building, we first need to determine the total price for the siding installation, which is based on the surface area:
Total price for siding = Surface area x Cost per square foot = 1840 sq ft x $11.67 = $21474.8
Now, we can calculate the total price per square foot of the building:
Total price per square foot = Total price for siding / Square footage = $21474.8 / 2016 sq ft = $10.66
So, the total price per square foot of the building is approximately $10.66.
*Keep in mind that labor input costs may vary for different people, but when working with a subcontractor, it's beneficial to know the $/unit of measurement they use. Additionally, purchasing the materials yourself can help prevent the subcontractor from marking up the material costs and save money there.
This price does not include removing of the old materials; this is for new construction. It does not have scaffolding which may be needed, and it does not include overhead and profit for the GC running the job.
These are internal numbers that a GC would use to come up with his calculation of the cost of installing new siding, and then he would add or exclude things like trash, scaffolding, his overhead which will include insurance, workers comp etc.
**For siding, I would likely not add 10% for waste because of all the windows and the doors.
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Here is the longer calculation version it originally outputted before I told it to shorten it:
Output
Let's first calculate the cost per square foot of the siding materials, including the 9.5% California tax rate:
Coverage area of each piece of siding in square feet:
Area = Width x Length Area = (8.25 inches / 12 inches/ft) x 144 inches Area = (0.6875 ft) x 144 inches
To convert the length from inches to feet, divide by 12 inches/ft:
Area = 0.6875 ft x (144 inches / 12 inches/ft) Area = 0.6875 ft x 12 ft Area = 8.25 square feet
Next, calculate the cost of each piece of siding including the 9.5% California tax rate:
Total cost per piece = Cost per piece + Tax Total cost per piece = $45.70 + (9.5% of $45.70) Total cost per piece = $45.70 + ($45.70 x 0.095) Total cost per piece = $45.70 + $4.3415 Total cost per piece = $50.0415
Determine the cost per square foot:
Cost per square foot = Total cost per piece / Coverage area per piece Cost per square foot = $50.0415 / 8.25 sq ft Cost per square foot = $6.0632
Now, let's account for the 10% waste:
Waste-adjusted cost per square foot = Cost per square foot * (1 + Waste percentage) Waste-adjusted cost per square foot = $6.0632 * (1 + 0.1) Waste-adjusted cost per square foot = $6.0632 * 1.1 Waste-adjusted cost per square foot = $6.6695
Next, add the subcontractor's installation cost of $5 per square foot:
Total cost per square foot = Waste-adjusted cost per square foot + Installation cost per square foot Total cost per square foot = $6.6695 + $5 Total cost per square foot = $11.6695
Therefore, the cost per square foot for the James Hardie Artisan V Groove Siding, including the 9.5% California tax rate on materials, 10% waste, and the subcontractor's installation charge of $5 per square foot, is approximately $11.67.
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