Flooring – how do you install laminate flooring with multiple rooms at one time with click flooring (since you can only put it in one way)

Strip flooring can be installed in any direction in any room, however the convention is to run parallel with the longest wall in most situations. Rarely is this type of flooring run perpendicular to walls in a hallway. Not only does it tend to make a hallway look narrower than it actually is, but can cause a lot of waste of material when installing. Don't be afraid of changing directions from the room to the hallway if your using a good wood product that can be cut cleanly on a table or chop saw. You simply need to make a very straight and slightly back angled edge (maybe 2 degrees) so the adjoining 90 degree slats are tight with no open gaps. This is extremely difficult to do with cheap laminate, but not so much with a good wood product.

There are transition pieces available for both styles, but they usually involve a change of floor level like a threshold and are not a good idea to use on open flooring, as they can create a tripping hazard, however they are fine to use in doorways etc. If you really want to have different directions between spaces, consider using a darker color "frame" around the room. This can make a very attractive transition to a large hallway or separate use area in an open design.

Let me add that I am NOT a fan of laminate flooring. Laminate flooring comes in a wide variety of quality levels, from extremely poor to fairly good, but share a common trait. They are always a "picture" of wood on some pressed paper or synthetic backing. They can be miserable to work with, easily damaged and almost impossible to repair after installation. Consider an engineered wood "click lock" instead. Pricing is very close and the engineered products usually are much more stable due to having a solid plywood backing, and somewhat refinish-able with a true hardwood veneer. They also handle the occasional water spill much better than most laminates that usually swell, bubble and blister at the site of water!

Another serious consideration is what type of flooring to use in a large high traffic area vs a smaller room. Laminates are almost always floating and will invariably sound hollow and creak as the temperature changes. For instances, walking across a cold laminate floor first thing in the morning can be like entering a haunted house at a fun park! Seriously investigate the advantages of a better quality engineered product.

While I disagree with your orientation, this isn't really that hard as long as you're using a floating floor.

Start by running a line of boards across all three rooms, and orient them so they are as perpendicular as possible to all the walls. (Alternatively snap a chalk line to represent the left edge of that single line of boards.

Now in each room, measure from the left edge (or chalk line) of the board to the left hand wall. Divide that distance by the width of your boards. The remainder is the width of your starter boards in each room. Rip your boards to fit.

Start laying the boards out in the room with the most distance to the left of the line. When you get to your opening, stop - lay the boards out in the next room until they come up to the opening. Run your line of boards from the first room into the 2nd room.

Now since its a floating floor, shift the floor in the new room to align with the board sticking into the room. Click the connecting board into place, and you now have a continuously aligned run.

Repeat for room 3.