I'm installing about 1,000 square feet of Trafficmaster Allure Ultra vinyl plank flooring. The instructions say to leave a 1/8" perimeter gap but do not say anything about an expansion gap at a certain maximum run length or between rooms. My installation area is roughly L shaped and the long runs will be on the order of 40 - 45 feet. Is it really safe to not put a transition between the rooms as the instructions seem to suggest? I can find almost no info searching. My understanding is that the vinyl doesn't really expand or contract but the house may, so the perimeter is what really matters. However it still makes me nervous.
Definitely check with Trafficmaster for their suggestions, they're really the only ones that know. But, I'd suggest back-beveling your cuts in the middle (or more places) of the full run to avoid any transitions. Back-beveling is just a 1 or 2-degree pie slice cut to the bottom...the top is tight but the bottom has a minor gap.
This way, if there is movement just the top would buckle & can be re-cut or trimmed in place, to fully remove the 1-time buckle permanently.