What are these things on my roof?

October 23, 2007 8:46 AM

I climbed up on our Philly rowhome's roof a couple months ago to have a look at it & came across a couple of raised sections that I'm curious about. Are they roof hatches? Skylights? Nothing?

There are a couple of pictures of the two things (crappy quality cause they're captured from a video, sorry): the first one is here and is almost smack in the middle of the house, on a peaked section of roof about 6 inches from the peak itself. The raised section is maybe 18-24 inches square, I'd say.

The second one is here, with a closer view of one of the corners here. This one's bigger than the other one and rectangular, maybe 24x36 or so. It's on the back part of the house, on the flat roof of a more recent addition. Both of them stick up about 4 inches, but are covered in the same rubber/tar/whatever as the rest of the roof.

I'm mostly curious if either one could be a covered-over access hatch or skylight, but I don't really want to go cutting a hole in the ceiling to find out. I realize it's probably hard to tell from the pictures, but figured someone may have something similar on their house.

posted by zempf to home & garden (11 comments total)

The small one looks like someone covered-up a roof vent.
The big one...I dunno. A hatch seems probable. Or a leaky skylight that someone decided to simply tar over and seal it up.

Are those accessible from underneath? In an attic?
posted by Thorzdad at 8:53 AM on October 23, 2007

I've got a rowhouse in Philly, too. I can tell you that your roof is rubber, and should probably be silvercoated. I can tell you that my roof does not have those thingys on it.

It's possible that they were leaky hatches that someone roofed over -- those hatches are notoriously difficult to keep sealed.

Who did your home inspection and how long ago? I know that if I called the guy who did my inspection, he'd check out the photos and let me know what they were.
posted by desuetude at 8:55 AM on October 23, 2007

The first one looks almost exactly like our roof. I know fro a fact that ours is a covered-over attic-access hatch. It is (was?) our only access to a very short attic.
posted by MrMoonPie at 8:55 AM on October 23, 2007

There's no attic (the roof is only about a foot or so above the ceiling in those spots), though I may get motivated & cut a little hole in the ceiling so I can peek, as my curiosity is getting the better of me.
posted by zempf at 8:56 AM on October 23, 2007

I doubt it's a skylight, but it may be an airshaft, especially if your row home is of some vintage. Think of the need to ventilate the 3rd floor of a Philly row home in peak summer - especially in times when more people resided in the house and the top floors were sleeping rooms.

Perhaps someone with more specific architectural knowledge will come along.
posted by Miko at 9:05 AM on October 23, 2007

Added another picture of the one on the pitched part of the roof to give a little better view of where it is (this is from the front looking towards the back yard). It actually seems closer to the peak than I thought it was originally.
posted by zempf at 9:19 AM on October 23, 2007

I'd seriously not recommend cutting into the roofing material unless you're planning on reroofing pronto. Introducing a place for water to seep into your house is asking for mysterious water damage somewhere. (Water will obey laws of physics that you thought were theoretical.)

The previous owners of our house didn't apparently want to pay to replace the entire third floor roof, so they put new rubber down on just the back half and burned it down. The seam probably held for quite awhile, but eventually water started seeping underneath. When we bought the house, the back half of the roof was like a waterbed with a substantial layer of water between layers of roof, and of course water had long been trickling into the house.
posted by desuetude at 9:26 AM on October 23, 2007

probably patched over remnants of old chimneys.
posted by Gungho at 9:44 AM on October 23, 2007

Oh, yeah, zempf, no appreciable attic here, either--I was using the term to refer to the tiny space between the roof and the 2nd-floor ceiling. I have peeked through a small hole in the ceiling to see what was up there, and found that there's not enough room to do anything with--maybe I could store suitcases or something, but it hardly seems worth the effort.

Here's a picture of the front of our house--you can see that there's very little space between the top-floor windows and the roof line; the windows, of course, aren't flush with the ceiling, and there's about a foot-high facade on the roof. And the roof pitches down from the front, so that's the most-spacious part of the "attic." The covered-over access hatch is at the back. Our home inspector told us that's what it was, but I guess I'm just taking his word on it--I haven't confirmed.
posted by MrMoonPie at 9:53 AM on October 23, 2007

Tarred over roof hatch. Most rowhouses here in Baltimore have them too. The hatch gives you access to the roof, obviously, but they're notorious for leaking and it's a security risk. If someone can get on roof X, they can walk across to roof Y and drop down into your bedroom.

I opened mine up anyway so I could put my beehive on the roof.
posted by electroboy at 11:59 AM on October 23, 2007

I vote for tarred over old chimney, you don't need so many access hatches. You could check to see if they line up with interior walls that could have had coal fireplaces/heaters (or still do.)

by the way, that's a tar roof, layers of tar and impregnated paper, many many layers. there's no rubber yet, until you put on a new roof! i wouldn't spend too much time walking around up there, it's a good way to damage the roof.
posted by geos at 2:13 PM on October 23, 2007