It is a fantastic time to buy for equity, but it will be extremely tough to cash flow as rental prices are continuing to decline.

I am self employed but want to build a spec home using the equity in my house as collateral.

Unless maybe that is counting people's $1M residences. or average price of homes in Austrialis is probably 1 mil or more. at least in the big cities

I don't have any investments yet mostly because my wife and I just got married and bought our primary residence.

Texas does have specific rules regarding home equity loans and cash-out refinancing (often referred to as "Texas Equity Section 50(a)(6)"), but these don’t prohibit homeowners from using funds for investment properties.

However if you are bringing no equity to the deal they might scoff at the idea.The other thing you could do is find someone who trusts you who has money and wants to lend it. ( Private Money ).

Investment Info:Single-family residence buy & hold investment.

Reverse Mortgages (HECM or Home Equity Conversion Mortgage) can be a FANTASTIC tool! 

Depending on how close I was to having 20% equity in the property and being able to avoid PMI, I’d consider using some of my cash to pay down the mortgage when I refinanced.

Residents with sufficient income will relocate to more desirable areas, causing a downward spiral of declining average incomes and deteriorating city services.