Anecdotal evidence suggests that ole Saint Nick is the Chesley Sullenberger of sleigh pilots. He can put that baby down safely on just about anything. Some say it's magic. We're more inclined to chalk it up to his three tours as a medevac pilot in 'Nam. Either way, few roofs make for an ideal LZ.

First off, the whole shebang—sleigh, flying ungulates, sacks of toys, Santa himself—weighs a ton. Actually, more like north of 60,000 tons, which is the estimated weight of the gifts alone, according to NORAD, which famously tracks Santa as he makes his Christmas Eve rounds. Moreover, says NORAD's Preston Schlachter, Father Christmas packs on an additional 1,000 pounds of body weight over the course of the evening—"Just on cookies and milk and yummy snacks."

Suffice it to say that the perfect roof would require some very particular engineering. Mark Graham, vice president of technical services for the National Roofing Contractors Association, says brittle materials like slate or clay tiles are obvious no-nos. Even asphalt shingles will break when frozen. Then you have the load-bearing problem. Santa wants to slide nice and easy down your chimney, not crash through your home and wind up in your basement. "A conventional roof system on a house is designed for 20 pounds per square foot of what we refer to as snow load," says Graham. "That's a far cry underneath the 60,000 tons." There's also the slip-and-fall factor. Take all this together and you're looking at a commercial-style flat or "low slope" roof, consisting of a concrete structural deck with a waterproof membrane, topped with concrete pavers, polyurethane foam, or even poured concrete, suggests Graham. Unfortunately, this could get expensive and still might not bear the weight. "I don't mean to be glib about it but the only thing we could really do is suggest Santa land in the driveway or the yard. The roof, although we'd like to have him stop by, is probably not the best place for him to be," Graham says. "I hope I don't get on the naughty list for saying that."

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