Thanks yall. No one was home at the time. Dad was at a doctors appointment and I was at work...my house is on the other side of the property.
Investigators came out yesterday and concluded the fire started in the gameroom...likely from the battery tender that was on the lawnmower parked under the lean-to.

So if any of you use a battery tender on anything, keep an eye on them. scope

CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax