Legal Question in Real Estate Law in California

Re: note and security agreement

If the parties have separated and the house is truly owned in joint tenancy rather than as community property, you can probably collateralize your note with one spouse's signature and your lien would affect only that spouse's part interest. In addition, the non-participating spouse should be informed in writing. If both spouses will cooperate with you by signing both the note and security agreement, you can obtain a lien on the entire property, which is much to prefer.

You don't say what kind of security agreement you have in mind, but the first thing I think of is a deed of trust. A real estate lawyer poracticing in Santa Clara County would be your best choice (try the phone book for one near you), but on a $10k deal an alternative might be to ask an escrow and title company if they would document and record the deal for you, for a modest fee. They may want to sell you a lender's policy of title insurance, which might be a good idea to have unless you already are familiar with title on the property you're lending against.

Avoid any deal which involves community property and you are dealing with just one spouse; the result is very likely going to be a Family Code violation and a void or voidable transaction.