From changing elevations to drainage and erosion issues to stumbling upon shale rock or sand, building decorative concrete into a hillside involves a lot of unknowns and unexpected costs. The Pott Residence in Saratoga, Calif., for instance, was a 4,200-square-foot residential hardscape with twists and turns from the start. We had to bid and re-bid five times, presenting various sets of plans and even more ideas. I designed much of the hardscape myself to move the project forward. We also faced challenges that any contractor should expect when working with hills, as illustrated below.
Bid, estimate right
Hillside project costs are hard to estimate. You need accurate elevation plans from an architect or civil engineer to even know how much concrete will be used. In many cases you won’t have access to such information, and the client may be unwilling to hire soil engineers, surveyors, or civil engineers to produce a detailed plan that includes, for example, stair locations and retaining wall heights. A certain amount of due diligence is required before estimating the hillside project.
For the Pott project, the original plans from the building architect had minimal hardscape plans and another from a landscape architect was missing details for elevations, footing sizes, wall heights, etc. We had to lay out walls and perimeters and send a foreman and an estimator to shoot grades. In this way, we established wall heights, which then led to specifying footing widths and depths and laying out the final shape of the walls. Only then were we able to calculate costs.
It’s also never a bad idea to overestimate costs, as most hillside projects tend to go over budget due to dealing with unknowns like soil conditions. Although it’s best to bill on a time and material basis for these types of projects, hardly anyone wants to do that.
Planning and visualizing is as important as any other aspect of a job. Customer input is equally as important. Have multiple discussions and meetings with the customer from the first visit, and be prepared to redesign to suit client needs. Provide samples with various colors and textures. Like Goldilocks, the client will pick those that are just right for them.
Use enough manpower
You’ll need an adept crew, and all hands on deck to properly set forms for vertical surfaces, pour structural elements, and quickly strip forms to add decorative finishes. In the case of the Pott project, some walls needed to be stripped, colored, and finished all in the same day (actually in a few hours).
Don’t just guess. I have spent years tracking special “place and finish” labor requirements so I can calculate costs and labor for my projects. We use a metrics log based on the jobsite data I’ve collected to determine what type of labor is needed to provide a stellar finish. For example, I’ve found that most walls have a metric of one man per 80 square feet.