Have you heard of a Builder's Warranty?

[Sara C.]

We have a flip under contract and the buyer is asking for a "Builder's Warranty." 

Some background: this was a heavy rehab in a townhome community (cat/hoarder house) that involved taking it down to the studs and rebuilding from there. But it's not new construction; it was built in 1974.

I'm familiar with home warranties and would be fine with that, but I can't find any information (or cost) for Builder Warranties. 

Any insights or recommendations?

Thank you!!

Sara