What is this foam in my downspout for? Can I get rid of it?

Question

When we had our house's gutters and downspouts replaced a little while ago, the installer discovered that the bottom (end toward the ground) of one of the old downspouts was clogged with the black and white stuff in the pictures, which looks like a mix of dirt and some foam.

Since the stuff was at the bottom end of the downspout and filled it along with the drain, we decided to temporarily route the downspout onto the patio instead to avoid the water backing up or spilling out of the downspout.

My question: I'm wondering whether or not we should just scrape out this stuff as far as we can and call a plumber to finish unclogging the drain, or whether this stuff has any useful purpose other than stopping up the drainage.

• I know sometimes people put foam in gutters to stop leaves and pine cone needles falling in but those wouldn't go into the downspout, would they?
• If this were insulating spray foam, why would it be in a downspout, unless it was applied from outside by a careless person?
• Could this be a clumsy way to stop rats and mice from climbing up from the storm drain? We don't have any mouse problems in this house, and I would think water spilling onto the walls and foundation concrete would be a worse problem than mice.

Answer 1

It's a sediment trap. You don't want debris entering your underground pipe where it's much more difficult to remove.

Check the top of the downspout for a mesh or something and resolve the issue there. Leave the sponge in place. Either that or install a modern air gap debris filter mechanism.

Answer 2

As you can see that was a bad idea.

Filtering debris at the end of the downspout will quickly clog it. Using foam is another bad idea. It will break down and clog the underground pipe.

Done by a person who did not want to do the high balancing act of cleaning the gutters, understandable but wrong solution as you can see.

All product available on the market prevent debris from entering the spout, on the top.

However most will leave the derbies in the gutter and eventually clog it up there.

To avoid the high balancing act, I used the garden hose with long extension (available to buy) to spray clean the gutters wile standing on the ground.

So combination of both will work for long time.