Qualifying for a HELOC during the renovation process

[Chris Tindal]

My wife and I have just sold our first live-in flip and are seeking to put the funds raised into an investment property on the same street. We have had an offer accepted on a house which is solid structurally, but will need to gut the interior and re-work/update most of the systems (electric, plumbing, HVAC). 

We are confident that the income created from the sale of our first home will be able to fund these initial renovations, but realize we will need to locate additional funding to complete the entire renovation. 

After the crash course education received by listening to the podcast and hanging out on the forums it seems as though a HELOC would be the most enviable source of funding. How difficult is it to receive the desired appraisal amount with a property still in the middle of a renovation? Will the appraisal be raised drastically just from changing those systems, even if entire rooms of the house have not been completely finished?

I realize that there are other options for funding, and have also considered applying for a personal line of credit if the HELOC did not turn out to be a possibility.

Thanks for taking the time to read this post!