Building Costs Q&A – Are Online Calculators Any Good?

Short answer:  No.

And that’s because you’ll use them incorrectly.  They actually work just fine.  It’s us pesky humans that muck it up.

I recently received an inquiry from a young couple that is hoping to buy land and build a home in Sonoma County, CA.

I shared a budget from a recently completed project that showed how a 620 square foot custom accessory dwelling added up to over $200,000 in work.

Here is his response:

“I was somewhat surprised at the cost — are the various online building cost calculators just completely off?

We don’t have land yet, but we’re weighing whether to buy land or buy a house on a large parcel, and how complex and expensive the process of building is will help us make that decision.  (There are many of both options in Sonoma county.)

-B. R.” 

This potential client had used this online calculator:

The calculator looks impressive and the results are quite reasonable but it’s easy to miss the following costs: Permitting, impact fees, structural engineering, soils engineering, utilities, demolition/site clearing, driveways, sidewalks, site drainage and landscaping.

It is also REALLY EASY to select products and materials or quality that doesn’t match the actual tastes of the owner.  That is probably the biggest cause of getting costs that are “way off”.

For example, you might say mid-range bathroom which means fiberglass shower and vinyl flooring in the calculator but it means custom glass tile and Kohler brushed nickel in your mind.  When you go to buy that tile it will inch your budget up by several thousand dollars.  Do this 20 times and you’re way out of line with the initial budget calculator.

Those are the “surprises” that cause the costs of most projects to double.
Bottom line – If you have to choose between an online calculator or the actual amount someone nearby just spent, you’re better off starting with the real and recent example and working off of that.
For example – here is the online calculator budget when done properly.  The total is $229,000 for construction only and this is using a level 2 quality on a scale from 1-7. 
Screen Shot 2015-03-20 at 11.12.51 AM
The actual cost for this project was $220,000 for construction plus $40,000 in design, permits, engineering and other “soft costs”
Here is a picture from the New Avenue budget system that shows the first page of the final amount spent.  You can download the full cost of the project here: 620 Sqft – Design and Construction 2014Screen Shot 2015-03-23 at 2.39.08 PM
What is really fascinating and scary is that the same size custom home, when estimated in the calculator comes out at less than half the cost when you select mostly quality level 5 out of 7 (with 7 being the lowest quality and 1 being the highest)
Screen Shot 2015-03-20 at 11.24.01 AM
 At the end of the project, the online budget estimator was very accurate but an optimistic user who input inaccurate quality or finish goals would have been way off.  So, what is someone supposed to do?   We’d recommend you do both – use the calculator and call a local contractor to show you a budget for a recently completed project near you.
You can contact us for additional plans, budgets or sign up and use the New Avenue system for free here: Get Started

Have any questions? We are available to discuss your goals & ideas. There’s no fee or commitment. To request a time for a call, just click here and tell us when to call you.