Leaky gutter corners are present on almost every house and this almost always leads to soffit rot.

Peace Painting Co., Inc.
by Peace Painting Co., Inc.
I'm convinced there is a flawed technique that is repeated with every installation.
I've seen enough to know these corners are prone to failure and cannot be remedied. I would like to see something like a contiguous, one-piece corner, say a foot long on either end. Does anyone know of anything like that on the market. I would like to recommend something that is not going to cause the same problem when a customer needs new gutters. Thanks, Charles
Failed caulking causing soffit leaks
Underside effect, the beginning of rot
Good news, bad news
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  • I did some research on the NP1 sealant,. It looks pretty much like the same stuff I use that comes in the smaller aluminum tubes but in caulking gun sizes. I too think that would work fine. But unless you do a lot of sealing of gutters, you are going to waste a lot as you do not need that much to properly seal a gutter joint.

  • You just have to spec that the installer use a separate corner piece...sadly, many residential clients fail to read the bid or look for the details....they just look at the price. We're almost always about twice the cost of most gutter installers but we use separate corner pieces and hang with hidden hanger screws AND a separate aluminum outlet cup at the downspout. You'd be amazed at how many installers just fold down the cuts from the gutter and secure the downspout to that! Beyond that, most corners, even the one pictured, have screws or rivets through the bottom to hold it together. It's just common sense not to put holes in the bottom of something design to conduct water. I've used NP1 on roof flashings with good results but not on gutters yet. We used to use ParBond but my supplier went out of business and that seemed to hold up well. We use an elastromeric sealant on our roof repairs that I will have to try on some gutter corners to see if it holds before I recommend it....