We need to re-do a retaining wall and re-build an outdoor staircase that is actually an easement/fire exit for our neighbor, a church.
We know we need to get drawings in order to get a permit, but the initial quote was $3500 just for the plans. The church is sharing the repair cost with us, but their handyman balked at the price, and said we should be able to get drawings for 1/3 of that price. What’s an appropriate cost for landscaping designs that require structural calculations?
Full details on the project: we have a standard backyard lot (~50’ long x 25’ wide) in San Francisco with a steeply sloping yard. The yard slopes up, away from the house. The retaining wall at the top of the slope is rotten, but we think we’re going to just build a new wall in front of it, instead of trying to replace it. Additionally, there is a wooden staircase (the church’s fire exit) that traverses the length of the yard.
Based on your description, it seems like you may benefit from borrowing structural notes/graphics from a local builder if you happen to know somebody. You could do that for free. Of course, without knowing the height of the existing wall, it is hard to suggest a design, but most are shaped like an “L” with the horizontal portion extending back into the hillside to act as a cantilever. I would suggest doing an image search for “cantilever retaining walls” to get the gist of what you are looking for. It really depends with your comfort on the matter, and if you are comfortable asking questions, you can save yourself a lot of money on a retaining wall.
Rebar placement is the only difficult thing for most people as the building code is different, even city to city in the same state. A retaining wall isn’t complex engineering though. Most of the time for retaining walls you won’t need more than a simple drawing of the wall from above and a cross-cut drawing that shows the rebar placement within the wall with measurements to scale. That could be done by hand, or with a computer.
If you prefer to purchase plans, depending on the engineer/architect, you could have them either design it, or just purchase the structural notes (the cross-cut section). We have purchased structural details previously for $500, and have also had one completely designed from the ground up for $1750. You aren’t building a skyscraper, so you don’t need a fancy engineering company with a modern office (a cost that gets passed along to you). You could get a college kid in an engineering class to design one for you as a class project if you wanted.
A great source for information are concrete supply companies as they provide packages based on architectural drawings, and they may offer some advice (or drawings) if you place your order with them. The city will also answer questions (it’s their job) in regards to getting a permit passed. Commonly, they have coaching areas in permitting offices for that exact reason. I personally charge $500 on top of permit costs to submit permits in person, usually because it takes me off the jobsite, it is a pain to park, and I don’t like lines. You can pull the permit yourself for just the permit cost, but they will usually want to know the info on who is performing the work.
Do note that with most retaining walls that need permits, you will probably have to include drainage on the inside of the wall as part of the drawing. Once again, image search “retaining wall drainage drawing” and you can see what is commonly used.
