This is my first install. I've finished installing 5/8" bamboo upstairs without any problems.

I'm about to begin downstairs, but I'm stumped by how to handle this exterior door transition while keeping the necessary 1/4 to half inch expansion gap.

http://www.dslreports.com/speak/slidesh ... 9vcg%3D%3D

As these linked photos show (let me know if that URL doesn't work), I have a double glass door exit to a patio. The left pane is stationary and doesn't open. I was going to cover the expansion gap in front of that with quarter round bamboo.

The right door opens inward. As the photos show, there's an old pink threshold piece the door closes on to seal, and a screen door a few inches further out on a track. This pink threshold piece is about half an inch higher than the inside plywood floor. The bamboo laid on the plywood (with 30# felt paper beneath) is higher than the threshold piece, so would require the door to be cut a few millimeters to clear the bamboo.

I could leave the pink threshold in place, and butt the flooring right up tight against it, but the bamboo would be higher than the threshold and I'd have no expansion gap, which I assume is a big mistake.

I could leave the pink threshold in place and bridge it with a piece of bamboo T-molding, but again, it would result in a floor and transition strip that's higher than the threshold, which I assume will be a problem for a tight seal when the door's closed.

My other thought is using a threshold like this one:

http://www.lumberliquidators.com/catalo ... uctId=1448

And cutting the door to rest atop it, then sealing the outside of it, and/or perhaps lay a piece of silicon-sealed plastic quarter round on the weather side? This side of the house deals with NY State winters, but the door is under an overhang, and of course behind the screen (which I could put plastic over in the winter/fall).

Any thoughts on this? I have all the tools and equipment I need to get started on this huge downstairs job, but this one spot is making me hesitate because I don't want to lay flooring I have to tear up. Any help would be greatly appreciated!

You need a door sill. It looks like there isn't anything but an old pink threshold. If you don't have a doorsill the seasons will take their toll. Water will seep in, maybe when it rains hard, maybe when the snow melts, and your subfloor and joists will rot. That bottom door plate doesn't look right at all. Install a new aluminum sill and use lots of quality caulking underneath it, and where it butts up to the sliding door sill. You may want to even add 3/4" under your new sill using a solid piece of 2x6 (properly polyed or sealed). That way your new 3/4 hardwood will only require a little piece of 1/2" quarter round to cover your expansion gap. Altogether you may need to trim your door a full 2" (1 1/4" sill + 3/4" 2x6)

You can make your own thresholds instead of purchasing them at 3$ a foot. Just rip a floor board in half (or whatever you like), then turn it upside down and rip the top corner off with your tablesaw blade at 45 degrees. Round it off, sand and urethane it and you're good to go.