Here’s my situation: My home is a modular home. Each side is 13’ wide and the gap between the two sides is approximately 6” (outside of drywall to outside). The wood is ¾” hickory and runs parallel to the walls. Should I make a 6” filler with splines for between the 2 sides or should I make a threshold to allow for expansion?
Thanks in advance for your help.
Dan

An expansion gap is prudent. You can achieve this by filling in most of the gap with plywood, leaving at least a quarter inch between the plywood and the flooring on each side. Then cover the "gap with 7 inch wide by five sixteenth thick plank for a low threshold, planing the edges like a reducer strip. A 15 degree angle at the edges of the 7 inch oak plank ought to be OK, unless you would prefer an aluminum type of threshold. Distributors usually stock 7 inch plank in either red or white oak, but they may be able to order some for you if they do not stock it. Here in the SF Bay Area it is readily available. White oak will look best.