flooringjamblaminate-floor
I'm planning on laminating the floor. On the photo attached, where you see a passage between the room and ensuite bathroom. So, do I have to cut the underneath of the doorjamb with a rotary tool or something so that laminate plank goes under it? I've marked in red the jamb spot.
This online store has them for $15.90 each, and claims to be compatible with Dremel Multi-Max.
EDIT: Taking shirlock's advice in mind, the right tool for the job can make all the difference. I did a bit of searching, and DeWalt has an angle grinder for pretty cheap - only 4x the cost of the multimax blade! Ryobi has one for about half that price too.
Masonry wheels for it are fairly cheap as well. (Although shipping will get you - might want to go to HD or Lowe's for these.)
I have just recently tackled the same problem with my own hallway. The solution I did was as follows. I cut a piece so that it would fit the door opening and a little more, so that it will go under the door frame. I have cut this piece so that on one side there is still the laminate "click" side, while the other is naturally cut off (this is piece 2 in the drawing). This way you can attach another laminate piece to this one. Next, I cut a narrow piece of laminate (piece 1) that can click on to piece 2. Finally, I have cut piece 3 so that it will butt against piece 2. Since there is no "click" side there, there is a small gap (if you can cut it accurately enough without leaving a gap, the better). This gap I have filled with wood glue mixed with sawdust from cutting the laminate boards. For my particular laminate it is a very close match to the color of the laminate, plus is it quite a small section (for me it was around an inch). From standing height it is barely noticeable, and can be improving by careful sanding. If you have something better as the filler, than by all means use it.
You can switch between pieces 1 and 3 (in terms of which one will have the "click" side, depending on the rest of you hallway laminate orientation.
For the assembly, piece 2 (or the one it will gone with) should have the "click" partially removed, so that it can be slid from the opposite room, under the door frame and into place, with the a line of glue holding the two pieces together. Then piece 1 can be clicked to place, and piece 3 clicked and glued.
Edit: here are some pictures. First, the glued part. In the picture it looks much worse than in real life (also ignore the lack of skirting board). The glue goes all around the piece since there were some gaps in all directions and as I said, it is barely noticeable from standing height:
Here the opposite side of the doorway, where the piece is clicked. Note that the central part (piece 2) goes well under the door frame:
And finally the entire door frame. Excuse the blurry shot, but I hope it is enough to give you an idea of my installation:
Edit 2: Following the OP's comment, I have an idea about how to put piece 2 in place if you can't slide it from the opposite room. This requires you to not have finished placing the boards in the hallway. You'll need to place some temporary boards up to the door in question, then measure and cut piece 2. Remove the temporary boards and slide piece 2 from the hallway. Then you can continue laying the boards as usual. To connect piece 2 with the real board before it, you still have to slide it out a little (out of the hallway, into the next room), lay the board and slide piece 2 back in. Sounds complicated, but I can't think of another approach.
Best Answer
You don't have to, but there's not a great alternative to prevent gaps from showing. An "undercut saw" can be rented cheaply at your local tool rental shop. It's basically a circular saw with the table configured for horizontal cuts. Try to run the blade teeth toward the wood to prevent tearout.
You can also use a fine-toothed handsaw with a scrap of your flooring. Lay the flooring on the subfloor and run the saw on top of it, taking care to not let the saw jump and scar the jamb.