On Oct 8, 4:10*am, reflex wrote:
See photos at:

http://www.flickr.com/photos/43253095@N04/

Our house is pretty old, built in the late 1800's. Over time, the back
of the house (as well as our neighbors') has subsided a bit. Hasn't
caused any foundation problems, but it does mean that in places water
doesn't flow off the roof quite like it's supposed to anymore.

One problem is as shown in the photos linked to above. The built-in
gutter doesn't work anymore, and the water pools in a corner of the
roof (above the porch), flows over the side onto our deck, causing a
bit of damage including allowing mold and moss to grow where it
shouldn't.

How would you fix this?

I can see at least two ways:

1. Build a kind of dam using a plank of pressure-treated wood along
the side of the roof, so that water is forced to once again run down
the original gutter spout. I'd install the wood, cover it with tar
paper and roofing compound, and we'd be good to go. Maybe instead of
wood I'd use some sort of large vinyl drip edge or whatever, if I
could find it. I'd try to install the wood in a way as to not pierce
the roofing material already there, so leaks can't develop.

2. Install a new gutter alongside the edge of the porch overhang. I'd
have to connect it to the main downspout (shown in the pics) or else
install a new downspout somewhere close.

Advice and opinions? Much appreciated! Thank you!

Your detail / closeup photos are good but the overall situation needs
on context.....you need to provide global photos shot from the
"normal" human perspective. Bird's eye views are difficuult to
undersand without having seen the "overall" picture.

cheers
Bob

oriignal question.....based on limited input, add a douwnspout, But
I'm guessing oyu have some rot / structural issues that of hand in
hand with the gutter / drainage problem