How can I use a tax deferred retirement vehicle as a downpayment

[Jordan Low]

In Feb 2015 I purchased a single family residence where I reside and rent out a room.

In a couple years, once I have saved up enough money for a down payment I want to purchase another single family residence.  I will rent out my first house, and live in and renovate the second one.

Currently I have been saving all my money in my stock account.  I realized I could be missing out on a lot of money by not taking advantage of my tax deferred accounts.

My current thinking is to max out my 401k for two years and then turn the 401k into a self directed IRA and use it for a down payment.

As you can probably tell I am weak on this issue. Is there a way to use my Roth IRA and a 401k as a down payment for a second property which I will live in for a couple years?

Thanks for helping out a IRA noob,

Jordan