Retaining Wall

It's become clear during our planning that the retaining wall in our backyard needs to be replaced sooner rather than later. We knew that it was a liability, and a significant expense. When we bought the place our inspector, agent, and contractor all suggested it could cost around 20k and would probably have to be taken care of within a few years.

Both the north and east walls, which hold our yard about eight feet above our neighbors', have problems. The north wall is buckling and leaning a foot over our property line, and even a steel brace installed a few years ago has only postponed its inevitable collapse. The east wall is cracked and crumbling, and will clearly need replacement but is less urgent.

Unfortunately, we can't defer repairs because they could compromise the structural work we're doing on the lower level by resettling the soil, so we must address the retaining wall first. Also, the estimate came in way above what we were expecting - around $39,000 to fix both walls! The combined urgency and magnitude of this expense have really impacted what we can afford to do in the first phase of construction, so we've been trying very hard to pare back.

We have contracted with a structural engineer, who we liaise with via our architect. This is an arrangement recommended by our architect (who also recommended the engineer). This has caused some communication problems; since we don't have direct contact with or control over what's produced by the structural engineer, we have had trouble understanding what our options were, or providing necessary details to our contractor to get proper estimates.

The engineer produced three options for the wall - our contractor ruled out two of the three because they required extensive drilling, and our backyard is solid bedrock so this would be very costly. The remaining option is a key-and-footing design.

Drainage

Every retaining wall needs to account for the water that accumulates in the soil. Either drainage must be provided, or the wall must be built stronger to account for the higher static load of water-laden soil. The least expensive option is usually to "drain to daylight" which lets the water run out to some neutral place like the street or an easement.

Of course, we can't drain to daylight and a thicker wall would be too expensive. So we need to use a "sump pump" to pump the water from the bottom of our wall up to the level of our sewer. Drainage wasn't part of our original estimates, and the pump needs maintenance lest it get clogged. This is disappointing, but if it saves us tens of thousands of dollars, it's worth it.

Cutting costs

This is a huge expense, and doesn't really provide any improvement in quality of living, so we're open to deep cost cuts as long as the wall does its job and is seismically safe. Here are some things we are doing (mostly at the suggestion of our contractor to save money):

• Using concrete block (CMU) instead of solid poured concrete. This is weaker structurally but our engineer approved its use.
  
• Doing only the north wall first, not the less-urgent east wall.
  
• Piling the excavating soil into the yard and tying it back rather than hauling it off and back onto the property.
  

The final estimate is around $24,000 for the wall itself, plus another $5,000 to install the drainage and pump, plus the cost of the pump itself (anywhere from $2-5,000).

Permitting

The permit for the work is "over the counter" meaning it can be turned around almost immediately and is fairly inexpensive. We have the detailed plans from the engineer and are taking the permit to the SF Building and Inspection Department ourselves (rather than paying the architect's office to do so). San Francisco also requires that the contractor have an OSHA license for any excavation deeper than 5', which is very strict compared to neighboring counties.

Construction is imminent, and we're very excited about an actual, tangible improvement happening to our home sometime in the near future.