April 22, 2008

Into the Ceiling

So even though Spring is here . . . We're still inside trying to figure things out. Our next step was to determine the structural load capability of the roof in order to determine how to proceed with getting the deck and green roof built. So we had to go into the ceiling and look at the beams.

I was excited to inspect the roof from below – to see the size and condition of the beams holding up our roof and measure their spacing. I choose the side of the skylight to cut into the drywall so that it would be least intrusive. It would also allow us to look above the ceiling without actually cutting into it. After removing a 10” x 18” drywall piece in the side of the skylight niche, I caught a faceful of some really old air. I mean who knows when this space was last open?

What we found was true 3” x 7” beams that are spaced 24” apart on center. From what I understand this is not great news . . . the depth of the beam is the key number here and seven is just not that impressive. New wood decks are often framed off of 2x12s spaced 18” to 24” on center . . . in other words with a lot more load capability.

On the positive side, the quality and integrity of the beams seemed intact; with no dampness etc., though one of the beams looks like it had some water staining at some point. Everything up there now seems dry as a bone. We actually have about 12 inches of space between the ceiling and the roof, which means we could raise our ceilings if we wanted to. Right now, it’s not even a consideration, with all our money and resources devoted to the green roof project.

One key thing to note, the load-bearing walls do not extend to the ceiling (12 feet) but stop at the fourth floor ceiling (11 feet). In this case, the load-bearing walls are the interior walls that run down the center of the building separating our apartment from our 4th floor neighbor. So what that means is that we will consider cutting into the roof and building up that load bearing wall to form a 2’ high parapet in middle of the roof. We would then frame the deck, and if need be, the green roof off this parapet and the side parapet.

But, we still have a lot of questions - What can we expect to pay for building up a 2’ parapet from the load bearing wall? How does this differ price-wise from using steel? We would like to still consider using steel, but want to know the price differential between these options. Is steel two times more expensive or ten times more expensive? Will the 3x7s at 24 inches on center be enough to support the 17 lbs/sq ft of the green roof modules?

Posted by Green Roof Guy at 11:35 PM | Comments (5)

Trackback Pings

TrackBack URL for this entry:
http://www.brownstoner.com/mte/mt-tb.cgi/4636

Comments