Planing the floorboards vs. Hardwood threshold

Is that a 25mm drop? if so lay conti board or 3/4" plywood on top.

A far better solution would be to use floorboards laid on appropriate thickness of thin battens in the dining room. Then the problem goes away and the outcome looks much better as well.

Certainly doing what he is suggesting makes no sense for all the reasons you describe. I did an exercise like this for some boards used as part of a wheelchair ramp, although it was only the last couple of boards. To get the accuracy involved running the boards through a thicknesser using a jig to create the slope across the width of the boards. It worked well but was quite a fiddle to do. Planing that amount by hand and getting a reasonable outcome would not be easy to do.

Can't he simply raise the dining room floor?

For purposes of illustration I simplified the scenario. In actuality the lower floor (screed) is about 50 sq. metres consisting of two rooms (one of which is actually a dining room) while the kitchen and the adjacent open plan seating area consists of 25 sq. metres. I also neglected to mention that the screeded area has a hot water underfloor heating system, so my guess is that your suggestion (boards on battens), while aesthetically optimal, would compromise the heating efficiency. I think the potential for c*ck-up involved in planing the boards (not to mention the possibility of the laminate floor having conniptions when encountering the changes in levels) is heavily out- pointed by the low-tech, hardwood threshold which, while not a beauty in itself, should perform to spec.

Thanks anyway.

Edward

Probably not. If you are using underfloor heating in a concrete floor, you have a very long thermal time constant - meaning it will take a long time (hours) for the temperature to change significantly. There are special control systems to address that issue. If you were to add a layer of insulating material, it would reduce the output, but wood floorboard is not that effective an insulator, being about 10 times worse than insulating material.

Planing the boards over a wide area is a bad idea, I agree.

A hardwood threshold is a solution but if arranged as a step becomes a trip hazard. The better solution is not to use laminate floor - for lots of reasons.