Are the gains that my self directed IRA makes taxable?
Not usually. If a self directed IRA buys a piece of property and then sells it at a profit, the gains stay within the IRA. If you have a traditional IRA the gains are tax deferred. If you have a Roth IRA the gains are tax free. Note, you alter that result if you use leverage through borrowing, if you borrow 1/3 of the money then 1/3 of the profits are taxed.