Armchair Builder

Buying Land: Minimize Cost Overruns

Buying Land Without Surprises

Buying Land: Check for Subsurface Rock

When you’re buying land to build your future dream home on, it’s extremely important to do some due diligence prior to finalizing the deal.  From zoning to soil checks, a little extra work performed upfront can save you tens of thousands of dollars and a bunch of headaches.  I drove by a new custom home site last week and took this photo of a backhoe chiseling away at rock just below the surface to make room for the foundation.  This will add thousands of dollars to the cost of the project and slow the schedule down to a snail’s pace.

Rock Removal Costs

Rock can make a great base to place a foundation.  But it can also cost you big bucks if removal is necessary.  In the case of the new home site above, the rock is just below the surface of the ground.  And because the site slopes up steeply from front to back, it’s necessary to cut into the slope to make room for the new home’s footprint.  So, a large amount of rock will need to be removed to get the foundation installed.  Rock will also need to be removed for water and sewer lines, electric and even the irrigation system.  Basically, anything that runs underground will require rock removal for installation.

So what is the process for removing the rock?  Unfortunately, this particular home site is in an existing community which removes blasting as an option.  If the lot was out away from other structures, it might have been economically feasible to use explosives to break the rock up for easy removal.  Instead, a backhoe with hydraulic rock hammer must be used to pound away at the hard materials.  This is an extremely slow process that can take weeks to complete.  Once the stone is broken up, there are three options for dealing with it.

  1. The large pieces can be used for retaining walls and landscaping on site.
  2. The rock is placed in a crusher where it is ground down into smaller pieces to use for fill on site.
  3. Rock pieces are placed in trucks and hauled away.

Probably the least expensive alternative is to use as many pieces as possible for landscaping on site.  This eliminates the need for an expensive crusher.  Hauling off site could be cost effective if the dump location is close by.  Here’s a look at some of the costs for rock removal…

  • Backhoe Operator – $60-70 per hour
  • Backhoe Rental – $965 per week
  • Rock Crusher – $8,000-$10,000 per week

Investigate Prior to Buying Land

Based on the cost numbers above, you will most likely want to spend some time reviewing subsurface conditions prior to buying land.  What are some ways to investigate the soil at the new home site?

  • Geotechnical Engineer – Hire a soils engineer to help with your investigation.
  • Neighbors – If there are neighbors close by, ask if they encountered stock when building their new home.
  • Developer – Ask the company that built the community to see soil reports in the area of your lot.  Developers drill soil test borings to determine feasibility of a project prior to starting.  Knowing what is below the surface helps them to create cost budgets for developing the property.
  • Test Holes – You may want to hire an excavation company to dig a few test holes on site.  These test holes will give you an indication of the types of soil and rock below the surface prior to buying land.  Be sure to get approval from the land owner and have a utility locate performed prior to digging.

If you’d like to know all the things that a professional builder reviews prior to buying land, check out this video that introduces the Armchair Builder Lot Purchase Guide.  The lot/land for your new dream home is probably the single biggest cost for the project.  So, be sure to check it out properly before signing a contract.

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