Several years ago I got a call from Jim, a prospect who was looking to hire a custom builder. After our initial meeting, Jim offered me a unique proposal. Jim is a businessman who owns and operates a local prominent privately held golf course. He had secured an option to buy two lots located at the end of a cul-de-sac which were only for sale as a package because one of them had challenging grades.
Before Jim called me, I tried unsuccessfully to buy both lots from the seller, Steve. The meeting with Steve prompted Jim to approach me with this unique proposal: Jim asked me to build him a custom home and to buy the adjacent lot for a spec home. Steve would not sell the uphill lot without selling the downhill lot.
My building permit obligations required a Lot Development Plan be prepared by a professional engineer. My PE prepared the LDP and the town engineer approved it without comment. In order to accommodate the 18 percent slopes, which dropped from the front of the home to the rear, I intended to build a double foundation under the basement slab so the footings rested on virgin soil. After I brought my architect to the site, I began to fully understand what physical challenges the steep grades presented.
Bob, my architect, cautioned me to consult with a structural engineer and a soils engineer. I located Dave, an engineer certified in both specialties. As I nervously awaited his recommendations, I wondered what would happen to my eroding margins. I began to question how I got into this mess and whether I’d have any profit left after spending money until the conditions were properly addressed.
After months of soil testing and cajoling Dave to finalize his suggestions, a plan was created. First, he explained that had I proceeded to build a double foundation in order to put my footings on virgin soil, eventually gravity might have pulled the foundation down the hill. He explained that I’d be building without a double foundation and that I’d be pouring my footings on a man-made plateau of 10 ft. of compacted fill. This all seemed contrary to the building practices I was aware of until this situation arose.
Here is where it got really interesting. Dave required that we strip the topsoil off the lot from the rear wall down the backyard for 500 ft. Then we needed to replace the topsoil with stable fill and compact it with a vibrating roller in 2-ft. sections, working our way back up the hill until we reached the rear footing for the new home. This has sat for the past 10 years without any cracking or movement on the side of the mountain. His initial estimates called for 1,500 tandem truckloads of approved stable fill.
Luckily for me, a major commercial job was looking to lose their fill dirt from only five miles away so I got all the dirt and trucking for free. Fortunately, I hadn’t presold the home to a transferee who almost bought it during preconstruction. We were in a rising market and I kept the home off the market until it was done, raised my price to obtain 20 percent gross margins and sold it upon completion for $1,200,000.
This is my advice to anyone considering building on a steep slope: Do not assume you can just dig deeper and hit virgin soil. Do not commit to building until you have consulted with the proper specialist. Remember that just because you are dealing with an engineer, he may not have the proper training to advise you on all site conditions. And, finally, never proceed if you think you might benefit from additional expertise. Rely on your expert’s advice as I did. Luckily for my situation, I ended up with the right specialist and I still managed to make a profit.