*As a home gets larger, I was wondering how to estimate construction cost beyond a standard square foot estimate.*

For example, I plugged in numbers on the free cost estimating software for a 3,000 square foot home of average quality in Southern California and I came up with a cost of about $100/square foot, $300,000.

If I double the size of the house to 6,000 square feet, the calculator comes up with $600,000, still $100/square foot.

How can that be? I can't believe there are $300,000 in additional material and labor costs.

For example, it can't cost twice as much to build a 20 foot x 20 foot bedroom versus a 10 foot x 10 foot bedroom. It's just more lumber and drywall.

Any words of wisdom would be appreciated.

David

For example, I plugged in numbers on the free cost estimating software for a 3,000 square foot home of average quality in Southern California and I came up with a cost of about $100/square foot, $300,000.

If I double the size of the house to 6,000 square feet, the calculator comes up with $600,000, still $100/square foot.

How can that be? I can't believe there are $300,000 in additional material and labor costs.

For example, it can't cost twice as much to build a 20 foot x 20 foot bedroom versus a 10 foot x 10 foot bedroom. It's just more lumber and drywall.

Any words of wisdom would be appreciated.

David

Hi David,

I always love the” It's just more lumber and drywall”. That’s what professional home builder’s hear all the time when a client gets an estimate or bid.

Actually, it’s more lumber, drywall, insulation, floor covering, HVAC capacity, roof shingles, foundation, siding, labor, insurance, more bathrooms, etc., etc.

Using the same “Average Quality Class” for design and materials on the construction estimating software for both a 3000 sq ft and 6,000 sq ft version of a typical one story ranch on slab home (no land, impact fees, or other local fees, and no garage) in San Bernardino CA, I came up with an approximate total cost to build for

**2016**of $262.511 for the 3,000 sq ft version and $504,417 for the 6,000 sq ft version.

Homes are measured in square feet of living area (heated space).

More square footage equals more money. That's pretty simple.

How much more? That’s the hard part.

That’s why a cost estimate based on “cost to build per square foot” is at the very best, a very rough estimate.

That’s why the Estimating Software has 6 different “Quality Classes” for 10 major categories.

But as I always say, until you get actual bids and estimates from contractors and suppliers, or General Contractor’s if you are using one, your best efforts at estimating will remain “approximate” estimates.

For more thoughts on this simple yet complicated thought, read my answer to the frequently asked question “Is the cost per square foot to build the same for any size house?” on my FAQ’s.(Scroll down)

Well David, you can see that your question is a frequently asked question.

Good luck, Carl Heldmann