Land + house as downpayment to build second house on same property...possible?

[Brandon Stephens]

Please advise me on if this financing scenario is even possible!

My wife and I own a 12ac parcel of land in rural North Carolina. Once we pay off the land loan in about a year, we plan on using the paid off 12ac parcel as a downpayment to build and move in to a small, simple 1000sq ft house (with no garage) for $250K. Land is worth about 80K, so total primary residence mortgage will be around 170K. Once the mortgage for this small house is paid off in a few years, there will be no debt on the house or the 12ac. We presume that the paid off property at that time will appraise for around $350K.... 

Here's the part I need an answer for:
We would like to build another larger house on the same property for us to move in to and to use the small house we just paid off as a rental. Can we use the paid off 12ac + small house all as a downpayment to build the larger house on the same property? Searching the internet, I can't seem to find any info on using land PLUS a house as a downpayment to build on the same property.... Is this even possible? There's plenty of info on land as downpayment, but there's not much i can find on land & house both as a downpayment.

(btw, the property has no deed restrictions, no subdivision stuff, and the parcel is outside the city limit....the only zoning that may apply would be county. My question is strictly concerned with financing/mortgage requirements).

Thanks!