Parallel to the longest run.

Great, now I'll have to find something else to obsess over ;)

Thanks!

It's probably not a deal breaker but consider that one way might use more material than the other.

I agree. The long edge of the plank *should run the long length of the SPACE (not necessarily the house). This can be modified for the space...but this is the "general rule".

What should I do laying engineered wood planks in an L-shaped room? The shorter arm of the L is the good sized dining room and there is a door that leads into another room that will have the same flooring. That essentially elongates the short arm of the L.

There are several things that must be considered. I like to use the concept of MOST amount of flooring that follows the general rule. If you have a single room (lets say 10' x 10' = 100sf) and then the REST of the space is much, much larger (say 600sf), you would want to try to keep the MAJORITY of the flooring (600sf) sticking to the rule of "longest length = long run of the room".

The other question with hardwood becomes wooden subfloors. Sigh. Wooden subfloors over joists change the equation. Hardwood floors must be run perpendicular to the joists - no matter how big/small the rooms are.

So...without knowing your set-up, without knowing your subfloor, without knowing the direction of sunlight, without knowing very much of anything about your situation...the majority of the home should follow the rule of thumb. Unless other factors contribute to changing this. Which I can't tell because there isn't enough information.

And just for fun...diagonal is always an option = 15% waste and a more expensive labour bill.

@B T, we are looking at Farmdale Caramel for our current kitchen remodel. Which Armstrong flooring did you end up using? Are you happy with it? Thanks!