First up, it turns out they're far less deadly than we remembered, at least for our almost-2yo. We'd decided not to visit France this summer because we felt K2 wasn't quite ready for the house--or we weren't quite ready to shadow her 24/7 across all the levels and gaps. It was probably a close call, but we feel pretty safe with her in the house now.
As the diagram above illustrates, there are really only two possible gaps in the railing we needed to address, and they're both vertical spaces between railings, not the horizontal railings themselves. [Note: we did have an important talk with K2 that Grandma's house is NOT, in fact, full of ladders.] The real danger is what we always knew: slipping and falling down a stone staircase onto a stone floor. Short of encasing her in bubble wrap, though, all we can do is keep track of her as she moves.
[Hilarious/interesting side note: K2 has taken a while to acclimate to multiple staircases. If you're half a level up, she'd automatically take the first staircase that moved toward you, whichever direction it went. Only after a couple of days was she able to figure out that she needs to choose up or down, too.]
Anyway, the barriere de neige solution: It's true that there is not much neige in the south of France at the moment, and thus not much snow fence. Fortunately, there's always construction, and plenty of grille de travaux. These smaller, 30cm tall rolls [EUR16/ 10m] would work fine for smaller coverage areas, but even that seemed a bit much for our situation. So I started poking around for other suitable barrier material.
Zip ties were a breeze to find, in the cable section. Wrapping our gaps with co-ax cable seemed like a viable alternative. Also considered: flexible plumbing hose. Rope. Not considered: garden fencing.
I settled on bamboo stakes, which I lashed in a criss-cross pattern to fill the space between the rails. It's very strong, but has a very little give. And it goes up and down quickly. Most of all, it's sufficient deterrent to keep K2 from trying to get in the gap, which is the key here, since the risk here isn't from an accident, but from a deliberate effort on her part.
How old is K2 again?
Oh I don't know--I feel down a flight of stairs and landed on a slate floor, cracking my skull open upon impact. Toughens a kid up for the brickbats of life.
Exact same predicament at our house with near identical stairs and railings, you'd be surprised how many ways there are to Jimmy rig a baby gate to work.
http://yaletowndad.wordpress.com/
Normally I would accuse blogger of cut and pasting a house from Architectural Digest, but your street cred is intact.
Chouette! C'est magnificent, oui?!