How to Repair a Leaking Gutter Union Joint (and Poly Tunnel)




here's an effective way to carry out gutter union joint repairs 

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Step 1:

you'll need roof repair compound and weed control fabric. do not use bitumen, it is cheaper but it is not the best product as it is not sticky enough.

Step 2:

a ladder stand off is needed

Step 3:

for a gap like a window just strap on a piece of wood as shown

Step 4:

cut the fabric to fit the gutter joint

Step 5:

clean the joint, plain water is just fine

Step 6:

previous pointless sealing with silicon

Step 7:

joint clean and dry.

Step 8:

keep the sealant in a bucket to prevent spillage

Step 9:

joint clean and ready for sealant application

Step 10:

apply the sealant generously, wear gloves as it is very very sticky

Step 11:

then apply the piece of fabric pressing it down, the sealant must penetrate the fabric

Step 12:

then apply another coat of sealant on the top. job done.

Step 13:

this method is also useful to repair rips in a poly tunnel, you need to apply the garden  fabric on both sides (inside and outside)

Step 14:

as shown earlier, it does a good job.

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    14 Discussions

    Paul Thompson

    7 months ago

    Good job, however why didn't you just buy a new gutter union? they retail for around $10, i find in my work these types of gutter repairs fail at some point unfortunately. Is yours still holding up?


    5 years ago on Introduction

    yes there is I had a small leak the other day after pondering on the subject I came up with a solution (BEING A CYCLIST i HAD LOADS OF USELESS INNER TUBE) so I cut off a length of tube and unhinged the guttering placed the strip of tube in the gap of the joint where the guttering was laid and resealed it by clipping it back into place it works no leaks

    1 reply

    Reply 6 years ago on Introduction

    Next "how to pitch a tent"

    Might just use a few pieces of thin cardboard. Seems more flexible than a shim.

    Bill WW

    6 years ago on Introduction

    Nice work, Robz.
    Never though of using the weed fabric, although there is a partial roll somewhere in a corner of my garage.
    It became obvious to me years ago that using compound only simply will not work.

    1 reply
    robz40Bill WW

    Reply 6 years ago on Introduction

    Initially I thought of a rag or something but weed fabric proved to be ideal as it is porous, thin, pretty strong and made to stay outside for years anyway. It ticks all the boxes.


    6 years ago on Introduction

    Gutters should run the whole length of your house. Prior to have my gutters replaced they were butted together but, not like in your pictures. You did the right thing by applying a coating of roofing cement.

    3 replies

    Reply 6 years ago on Introduction

    Yes you are right. It should but that's the way it was installed years ago, now waiting for the rain not a hard thing to get in Britain. And you have a nice set of instructables.


    Reply 6 years ago on Introduction

    Well thank you for your kind words! I hope you fixed the leaky gutters.


    6 years ago on Introduction

    Well done !…
    Step 12 :
    Rest on the couch and watch Alfred Hitchcock's move Vertigo !!…


    6 years ago on Introduction

    Thanks for posting this. I have the same problem with my gutters. I've tried the silicon caulk, which was ok for about a year, but then it started leaking again. I'm going to try this, now.