With the multi-point locking systems, you have the bolt that extends out into the secondary door (or door frame if you only have 1 door) at the level of the handle, you have a smaller "bolt" that extends out of the top of the door into the upper door frame and one that extends out the bottom of the door into the sill. When the lock is engaged, all these bolts are sticking out. If someone engages the locks with the door open then tries to shut it, the bolts slam into the surrounding frame and damage it. Walk into just about any showroom with French doors on display and take a look at the frames (especially the upper frame). That was one of Pella's selling points was that their mechanism was made to push back into the door if the lock was engaged with the door open and you then tried to shut it. After it was shut, the locks slid back out of the door and into place within the frame & the door is locked with no damage to the surrounding frame, sill or adjacent door. If you're worried about not having a multi point system for security reasons, you can always do a regular deadbolt and slide bolts at the top & bottom. Typically the slide bolts will be much longer than the short little bolts on the integrated multi-point system for a higher level of security IMO. My thoughts on this is that its overkill--if an intruder wants in, he's going to find a way--odds are he will just break the glass and turn the locks whether multi-point or deadbolt. Plus deadbolts & slide bolts are easier to remember how to operate--there is usually a trick to engaging the multi-point lock system. I think with my Mom's doors you have to turn the lock a couple times then flip the lever up to engage the lock. Your secondary swing door of the French door set should bolt in place. That's the biggest part of how the primary swing door is secured when locked. Hope this helps!

With doors you want to make sure that the threshold of the door is set in sealant and sits solidly on the sub-floor. It's common for this to not be the case, and eventually the threshold bows down and creates a gap where dirt collects and holds moisture. Don't know if this is what happened to you, but it's something to watch for. And like the other guys said, make sure that the bottom of the door itself is sealed properly from the get go. Also, personally, it doesn't hurt to remove the hinges and seal behind them as well.

I went to our Builders supply to try to get to the bottom of this, so I wouldn't fret all weekend over it. They were also puzzled and assured me they would get to the bottom of it. They sent the pic to Marvin and just heard back from Marvin that this piece that so concerned me was a piece that allowed for installation of the Marvin Shade system and is removed easily. I had no interest in a shade system and have no idea why this piece is on my doors or if they put it on standard but the whole thing really leaves me pissed. they also assured us that the installation looks correct. I sure as the he** hope so. Gentlemen, thank you for trying to help me and I still appreciate it if you have any concerns about this installation to let me know. i'm starting to hate this house.

The door can probably be lowered, although with one that old, I'd consider replacement.