On 11/8/2011 9:28 PM, Ron wrote:
I have a flat roof on a rowhome/townhome-style building that I want to
do a repair/fix on. I am looking for some suggestions or options for how
to do it, what materials to use, etc.

Basically, the roof is almost flat with just a slight pitch from the
from to the back. The pitch is maybe something like a 1 inch drop in
every 10 feet. Along the back edge of the building, the water runs off
and over the edge into a gutter and the into a downspout to the ground.
There is a problem with the way the gutter is done -- primarily that
there is no real drip edge to speak of. Instead, the water runs over the
edge of the roof and some of it goes into the gutter and some of it runs
down the fascia behind the gutter and down the side of the building. I
pretty much know what to do to fix the drip edge, gutter, and fascia
issues, so I am all set with that part. That part will involve replacing
the gutter and fascia and creating a drip edge so that all of the water
runoff goes into the gutter like it is supposed to do.

But, there is a secondary issue that I would like to address and fix if
I can at the same time. The secondary issues is that over the years part
of the roof has sagged just enough to cause a large puddle to form
across the whole roof starting at the back edge and going about 6 to 8
feet toward the front of the property. The puddle is about 1/2 to 3/4
inch deep along a line that is about 3 or 4 feet from the back edge of
the roof. In other words, along the back section of the roof, it
actually pitches slightly in the wrong direct causing the water to run
back onto the roof rather than off of the back edge of the roof and into
the gutter.

The existing roof -- strange as it may seem -- is made up of two
1/2-inch layers of sheetrock attached to the top of the roof rafters,
and then about 1-1/4 inch of asphalt sheeting or asphalt board of some
type with what looks like just asphalt coating on top of that. NOTE: I
posted earlier about this roof being weird and literally having a
sheetrock decking; and the property was built in or around 1945 (long
story, but true).

Nevertheless, here is what I am thinking about doing: Remove the
existing roof down to the rafters along a path about 4 feet wide that
goes all the way across the last 4 feet of the roof along the back edge.
Then add new 1/2 inch 4-ply plywood decking along that back 4 feet
across the back of the roof. That will enable me to put a new roof over
the new plywood decking, and because that new decking and roofing will
be thinner and lower than the original 1 inch sheetrock plus 1-1/4 inch
asphalt, I will be able to have the roof slope slightly in the correct
direction and run off the back edge of the roof and eliminate the puddle
that now forms across the back section of the roof.

My question is, "What type of roofing material could I use for the
4-foot wide new decking that I will be creating along the back of the
roof? The original roofing material is asphalt of some type, so I need
to figure out what goes on top of the new plywood decking along the
back, and how I will tie that into where that section meets the existing
asphalt roofing. In other words, "What do I use for the new roofing
material on this almost flat new section of roof decking that I will be
creating?"

I assume there is not enough slope to use roll roofing. I have seen some
roofing called Lo-Slope (or something like that) but I'm not sure that
is the correct approach. I also know there is glue-down rubber roofing,
or TPO vinyl roofing, or EPDM roofing. But I don't know if any of those
can be tied into the existing asphalt roofing that will be remaining on
the front section of the roof.

It may just turn out that I will have to have a regular roofing company
come out and give me a price to do what I want done and just let them do
it. But, if I could figure out what they would be doing, or what
materials they would use to do this, I may be able to do this on my own.

Any suggestions or ideas would be appreciated. Thanks.

Pro roof (probably membrane) on bare deck, and depending on how the
front and rear parapets are set up, they can insulate and reslope roof
at same time with foam panels. But before you get that far, need to find
cause and extent of saggy spot. Leak rotting decking and a couple
joists? Was a wall removed underneath? (They did that on a flat roof of
one wing at work. Oops. Didn't realize it till 18 months later when an
20"+ snowfall collapsed half the roof into occupied space.)

IMHO, some things are not WORTH doing yourself. Specialized roofs are
one of them.
--
aem sends...