On December 21, 1776, the house is burglarized by Wendigo Donner and a group of his accomplices. They break one of the containers with Claire's highly flammable ether. When Young Ian lights a match, the house goes up in flames and burns down overnight.

Does Fraser's Ridge burn?

The house on Fraser's Ridge does burn down, but, as you may have surmised since there are more books after this one, Jamie and Claire are not fatally harmed when it does. The house fire does, however, push the Frasers toward their next adventure: a return to Scotland.

Does the big house burn down in Outlander?

Fortunately, Claire and Jamie will not actually die but while the obituary confirms the house goes up in flames, the circumstances surrounding the blaze are unknown.