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.