What is a web-based valuation?

[Lilah Johnson]

I am in the process of taking out a HELOC on my primary residence with a local credit union so that I can get started in Real Estate investing. We have sent in all necessary documents (paystubs, drivers licenses, etc) and have been conditionally approved for the amount requested. Currently, underwriting is reviewing everything. I inquired about when an appraisal would happen and was told none was needed. They did a web-based automated valuation and my home appraised for $477,600. I'm concerned that this is a low appraisal when I look at comps in the area, they range from 505,000-535,000.

My question's are:

1) What is a web-based valuation and what criteria is used when it comes up with the property value?

3) Should I even be concerned about the property value when they've already conditionally approved me for the amount requested pending underwriting?

3) is this something that I can ask for a copy of?

Thank you for your help in advance!