Exploratory Surgery for Your Building Lot

Building Lot Surprises

The cost to complete the site work on your building lot can escalate substantially if your land hides surprises below the surface. For example, high ground water, ledge, and clay will require additional labor and materials when your general contractor installs your foundation. Ideally you and your GC will know whether any of these conditions exist on your property before he completes his contracting estimate. Otherwise he will exclude these conditions from his contract, since he needs to protect himself from these surprises as much as you do. Unfortunately your GC’s exclusions will leave you vulnerable to significant cost overruns.
A completed perc test will provide your GC with some information about these underground conditions.  But this information is only available if your property requires a septic system.  The experience of those who’ve built on neighboring lots can also give your GC a better idea of what he’ll find when he begins his excavation.  However, subsoil conditions can be quite different on abutting building lots.

Have your general contractor to dig several holes on your building lot to learn whether the subsoil conditions will threaten your budget.
Have your general contractor dig several holes on your building lot to learn whether the subsoil conditions will threaten your budget.

Building Lot Test Holes

What can you do if you don’t have any information about the underground conditions on your building lot and you want to know more before you move forward with your new home?  You can instruct your GC to dig some test holes where he is likely to work when building your home, such as where he will install the foundation, sewer line, or underground utilities.  Although the GC cannot determine from a couple of test holes what he will find in other areas of your building lot, he can reduce the chances that you will run into expensive surprises. When the test is completed, the GC can fill the holes to eliminate a safety problem.

Building Lot Insurance Policy

Exploratory digging can also be a valuable insurance policy if you have not yet purchased a building lot.  If the exploration reveals unexpected expenses that compromise your budget, you can renegotiate the price or buy another building lot.  If you still want the land, and cannot negotiate a better price, at least you can plan a more realistic budget for the entire project and avoid cost overruns.
Since you will need the seller’s permission to complete the test holes, include an inspection clause in your offer to purchase allowing you to have the building lot inspected by someone of your choosing and granting you permission to complete some exploratory digging.  Although you will likely be responsible for the cost of digging, which requires the use of a backhoe and will cost a few hundred dollars, the peace of mind will be worth the expense.
For more information about subsoil conditions on your building lot, see Finding and Preparing a Building Lot for a Modular Home in my book The Modular Home.