Size is 21' x 9', with 5 panels each of glass and screens (10 leaves total), all sliding to one end. The door in this image was about $25K materials and labor. That price is a bit higher than normal due to their unusual height - we normally make them 8 feet tall, which would make it probably 15% less expensive.

It's hard to say exactly what the true cost is, because the large opening forces some extraordinary structural solutions, i.e. increased cost of shear resisting elements and vertical load carrying beams. The nearest lanai column you see has one leg of a steel moment frame inside it, with a steel beam coming toward you and into another steel column in the foreground (not visible in this image). In this case, the roof trusses actually span from that frame, over this door opening, then across to the front wall of the living room (corner visible at the extreme right of the image). There's no beam over the door itself. That's a somewhat unusual solution, but is made possible because the doors actually roll on the floor; They're not hung from the header.

One nice way to save money using these doors is to put posts in the line of the outer pocket wall, which breaks the opening into shorter spans. If you're doing a more rustic style, where long spans like this aren't an aesthetic necessity, you can have the full opening without the normally large beams. If you go to my website and look at "Hale Nohea" on the Projects page, you can see an illustration of that technique ("Main Hale Interior", third image down on the page).

You can make these doors open on corners, too. This house has a corner unit on the Master Suite.. You can see that in the full set of images posted for this house at my Houzz profile page.

For the more usual 8 foot height, we figure these doors at about $900 to $1000 per lineal foot of width for purposes of budgeting.

The door system is a hardware component package offered by Dave Whitehill - www.dwfloortrack.com. You'll buy the hardware system from them, then install it into off-the-shelf or custom made leaves. Give them a call and they can connect you with installers. They also have excellent reference materials available for your architect or designer to plan with. Let them know that Paul Bleck and Dave Sanders sent you, please.

Thanks for your interest!

Dave Sanders