I've been thinking about using my primary homes' HELOC to pay for capex and maintenance costs on investment properties. Even though it's a variable rate (which is going up slowly these days) it amortizes the cost over 20 years making the out of pocket much less than using industry standards like $200/SFH door. Basically allows me to pocket much more each month I can use to keep investing.

Does anyone have any thoughts on this?  Great idea?  Terrible idea?  

How do you typically pay for capex or maintenance?  

I usually pay for the maintenance from the rental income.

So then you dont add anymore debt to your balance sheet. 

I have a separate sub-savings account where I direct some of the income from my rental into specifically for CapEx/maintenance. When I first started with my property small amounts were taken out of the rent but bigger amounts I paid on my credit card and then paid for out of pocket.