Originally Posted by
Jamie Buxton
I know a guy who was determined to put a sliding barn door on his shop, and also determined to make it seal as well as a residential door. (His shop is heated and air-conditioned.) His take is that it is very difficult to achieve a good seal with a sliding interface. If it is too tight it doesn't seal, and if it is too loose air goes through it. He looked to a minivan side door for his inspiration. When the door is opened, the first move is out away from the van. That move out (or in, when closing) is the one that does the sealing and unsealing, against flexible weatherstripping.
On his shop door, he uses the standard barn-door track and wheels to slide the door back and forth. However, he hung the door from the wheels with chains. Before it is latched, the door hangs an inch or so away from the building. He built four cam-clamp thingies which grab the inside of the door and pull it toward the building. Because the door is hanging on chains, it can move toward the building and seal all the way around.
The door is long enough that it overlaps the floor slab, and seals at the bottom just like at the sides and top. His seals are thick foam things intended for sealing the bottom of a roll-up door to a slab.
His design seals well, and I'm sure it was a fun challenge for him. However, if I were in his place, I'd probably use a pair of hinged doors -- like french doors but bigger and more robust. There's no need to invent anything.