What's holding up the roof?

Q. I had work done to the front steps of my house and the mason said that the columns weren’t really doing anything. They were loose and he took them out to show me. There’s a roof above that goes all the way across the front of the house, and I’m wondering if it’s safe not having the columns. Why were columns put in, and can I leave them out permanently? 

A. Most homes like you described don’t follow code or logic, but somehow stand up — temporarily, anyway. Your porch roof is probably made up of angled rafters and ceiling joists, hanging off the upper floor of the house like a big triangle. What attaches the roof are nails at the top, either side-nailed or face-nailed into either the wall sheathing (skin) or a horizontal ledger board. Any way you look at it, you’re relying on a handful of old nails to resist dead weight and live loads caused by snow accumulation and wind gusts.

Ignorance of these factors is bliss. Your mason incorrectly advised you, and must be very blissful. Unfortunately, happiness will end when one of several predictable conditions takes place. Either the upper wall will bow outward from the roof’s weight, the nails will fail from a sudden gust that smacks up against the house like a head-on collision, or those factors plus a snow load during one of those heavy ice and snow storms that normally cause us to make cookies and sit in front of our fireplace. You will, instead, hear a high-pitched sound, like whales communicating, as the nails twist, followed by thunder, and the house will shake. As you peer out your front door, it will be a strange sight, since you’re not used to seeing the bottom of your porch roof staring back at you, a few inches from your face.