Most states use one of a few building code standards which typically require 8" between the soil around a building and any wood of the structure.

You definitely don't want soil against wood no matter how dry it is.

You really should put a call into your local building department. They can give you the right advice.

Anything that may cause drainage towards the house should be avoided. A house has a sill plate, which is the interface between the foundation and the wall. Typically the foundation is waterproofed concrete/stone (in California probably slab on grade), and the walls are wooden. As Laag mentioned above, untreated wood won't last long, as the moisture will promote decay, and if it is above the sill plate there may be issues with water seepage into other parts of the structure.

I put raised beds next to my foundation this year on either side of the stairs. My problem was that the curtains on the steps are wood, and I didn't want to pile soil against them. Fortunately my porch foundation itself is masonry, so I could pile dirt against it. But what we did to avoid contact with the wood was to put a row of concrete slabs at the base of the curtain and then rocks so that the garden slopes up out of that well and reaches a high point somewhat further from the steps.

You could achieve the same effect against the house by putting a rear retaining wall of rocks, blocks, or 4x4s a foot or so away from the house wall, and filling against that. My guideline was to leave room to sweep.

KarinL

Thanks for the suggestions. I will call my local building department and see what the standards are for San Diego. My house is stucco with no wood showing and the idea of a free standing bed is OK. It may be a little more work but I'll check with the city first.

Stucco? Definitely keep anything away from the stucco! If you look closely you'll notice that there's a lip where the bottom of the stucco overhangs. Cover that up and you're covering up the vent holes on the underside of the lip. No vent holes, no air flow. No air flow, mold. With a stucco house you really want to be sure to keep those holes open, especially on newer homes where everything is buttoned up so tightly.

In that case maybe I should look at some large containers for the area but I still like the look of raised beds. I'm very glad that I asked you all first instead of charging ahead and ruining my house.

Thanks so much!

Andrea

My mom has a block wall constructed house in AZ. I would like to put a lasagna garden against her house. Since it's a block wall house, should I be worried about doing any structural damage by having a garden bed against her house?

Yes.