DIYbanter - View Single Post - Pro-Rib barn steel question

dpb

wrote:
I am using that Pro-Rib steel on a shed. I have used much of this
stuff and never had a problem. I did the roof on the shed and found
myself short one full sheet. However I had two half sheets left from
another project, (cut the full length) and they were long enough.
Weather was getting bad so I just overlapped the ribs and screwed them
on the roof. For some reason, as soon as it rained, I had a leak.
WHY? I have the ribs overlapping just like a full sheet, except these
do not have that one special edge that they put on one side of every
sheet. Yet, the ribs are fully overlapped and it was not even raining
hard. There are no holes, cracks, tears, or misplaced screws. How
the heck can the water jump over the rib? This makes no sense....

....

Not specifically w/ the particular product, but...

What's pitch on this particular roof? I'd guess one of three
possibilities--If the pitch is low you had a pooling problem where
didn't shed quickly enough and w/o the sealing lip it did run over the
edge. Alternatively, it could be the leak is actually somewhere on the
upper end and is simply running down that seam to get through or there
is simply enough capillary action w/o the seal to show up as the leak.
Would have to see, I think, to have any better idea in a specific case
such as this. I'd bet a closer inspection will reveal the
problem/mechanism when you get a chance after the rains...