Advice and recommendations for building a retaining wall?
I'd like to have a retaining wall built along the sloping side of my property. The wall would need to be about 6 feet tall in my estimate, and I want it properly done - load-bearing and with appropriate drainage -- it should be approximately 60 feet long. I understand that I will likely need an engineer and/or landscape architect involved with this, as well as the property line determined. I've been hearing quotes in the order of 20 - 40K for this work and though I understand it is a lot of work, that seems like an absurd amount of money, I see these retaining walls everywhere in the East Bay, almost every house in the hills -- have people always been spending this kind of money?
Also I am interested to receive recommendations for landscape design-build firms that can do all aspects of this work including design and engineering, for a reasonable price. This wall is not meant to be decorative and so I don't need a very aesthetically inclined firm or architect for it.
Thank you for any advice you have to offer!
-- confused & overwhelmed berkeley new homeowner
Parent Replies
We did it 2 years ago and yes, it's expensive. For one thing, there are multiple professions involved, and you need a permit from the city for a wall that's over 3 feet tall. This is in everybody's best interest, given we live in earthquake/mudslide country. The permit requires detailed plans drawn up by professionals. The city may require multiple permits and refinements to the plans, which costs more money since you are paying licensed engineers and architects for the drawings. You do need a survey if it's on the property line, which ours was. We already had a recent survey but if you need one, that's a few thousand dollars right off the bat, and it will be difficult to schedule it - there aren't enough surveyors here.
For the plans, you hire an architect or landscape architect (who should be licensed and should understand your city's requirements) plus a licensed general contractor to do the demolition and build. Or you can just use a licensed landscape design firm that does both the design and the build. That's what we did - we used Lazar Landscape and we were very happy with their professionalism and with the design.
A structural engineering firm must provide technical details of how the wall is supported. This is different from the architect's design. Engineers are not cheap, if you can even find one with availability. Lazar found one for us. The engineer will visit the site more than once, and draw up a detailed technical plan, which must be approved by the city. The overall design will probably need to be adjusted at this point. In our case, the structural plan required an existing fence to be moved back a foot to accommodate the technical underpinnings, so that was an additional unanticipated expense. Meanwhile, your contractor must coordinate with PG&E and EBMUD to find out if there are any underground services in the vicinity of the wall. In our case PG&E unexpectedly required us to reposition an old gas line and move the meter from the house to the street. This delayed our project 2-3 months while we waited on PG&E and it added another 20K to the project, because we had to hire a plumbing contractor to dig up the front yard and re-lay gas pipes and install the new meter.
Eventually the build can start. The old wall will be demolished, which doesn't take too long but it's often a separate contractor who does that. Then they bring in excavators to dig out the hillside, which may be another specialized firm. You will be amazed how much dirt they have to remove and set aside to re-fill after the new wall is built. The retaining wall itself may only be a foot and a half deep but there has to be several feet of structure behind and under the wall that you can't see, to hold back the hill. Excavation was expensive for us because we live on a busy street that does not have easy access for construction machinery. Finally, they build the wall! Pour concrete, lay bricks, etc. Our project took 8 months from conception to finish and it cost a fortune.
This sounds like a nightmare but we'd known when we bought the house we'd have to do it eventually. Our original 80-year-old stucco retaining wall was built with unreinforced concrete blocks and was leaning into a public sidewalk. You can see these all over Berkeley. So we bit the bullet and paid extra for aesthetics - new landscaping and an upgraded entrance next to the wall. We're very happy with the results - we have curb appeal now!
That seems low to me. I would expect more on the order of $60-80K. $100 might not be crazy depending on the soil issues in play.
-New homeowner who recently paid for a lot of construction