Barter is a taxable event. You would owe taxes on the full fair market value of the Bitcoin the moment that you trade housing for it. Things would work the same way if you bartered baseball cards or a car for rent.
Later, if it appreciated, the appreciation would be taxed as capital gains. But the original receipt is regular income.
BTC isn't considered a currency so it's taxed as an asset under
capital gains tax
This statement is wrong. Let's say you charge 1 BTC rent on Nov 1st. From the IRS standpoint your earnings are the dollar value of 1 BTC on Nov 1st, so that's approx $6k. You will be charged income taxes on $6k. Now, if you keep your Bitcoin until the end of the year and Bitcoin goes up to $10k of value and you sell your Bitcoin at the end of the year, you will owe income taxes on $6k and will have to pay capital gains on your $4k profit when selling your Bitcoin.
BTC isn't considered a currency so it's taxed as an asset under capital gains tax
You have a fundamental misstatement of federal tax concepts. Income tax is on ... income. Neither currency nor assets are taxed by the IRS. The IRS only taxes transactions. Those transactions may involve currency and/or assets, but it's not the currency or assets that are being taxed. If you receive $6000 worth of bitcoin as rent in 2017, then you have a $6000 transaction, and you owe income tax on that transaction. If you later sell that BTC for $10000 in 2020, then you owe capital gains tax on the $4000 profit. From 2017 to 2020, if the BTC isn't involved in any transactions, then there will be no tax on it.