Although the town had been water-soaked, the ends of beams catch most easily, dragon-fire having been applied to them.

• 14.015 and wooden beam-ends

“Beam-ends” is a nautical term, the bits of wood likely to get a dunking on a vigorous beam reach.  I’m going to call this a JRRT-original way of using this term, since he is referring to the buildings of Lake-Town.

“beam, n.1.” OED Online. Oxford University Press, June 2017. Web. 5 September 2017.