Underground Downspout Kits: Everything You Need

FDM is making things easier for contractors and eager DIYers by offering underground downspout kits that can be shipped throughout the country small package which eliminates freight costs.

There’s going to be an option to go with a two by three by four gutter adapter or a three by four by four gutter adapter. Those are the two sizes that are the two popular sizes. Make sure you get the right gutter adapter, but outside of that this is going to be super easy.

underground downspout kitsOur Complete Underground Downspout Kit Includes:

  • 15 ft Coil of 4 inch Solid High Octane™
  • 15 ft Coil of 4 inch Knife Cut High Octane™
  • 12 inch round D-Box/Distribution Box
  • Cleanout Kit to include Downspout adapter, 4″ Dualwall culvert pipe connection, 90° Dualwall 4 inch custom welded, 4 inch grate
  • 4 inch external snap coupler
  • FDM 200 year tape
  • Pop up emitter and 4 inch internal coupler
  • 12 inch Round Turf Restrictor Plate
  • 1 FDM Corrugated Pipe Adapter AKA Cone

So, we have a dual wall, nice straight, smooth piece of dual for the cleanout kit. So, nothing can get stuck in there. It’s really like Teflon inside. The gutter adapter is mini culvert pipe. So, you got a piece of mini culvert pipe with your gutter adapter, and your clean out. We have dual wall culvert pipe welded together by the craftsmen at Baughman Tile company.

We have a 4 inch external snap coupler, so that you connect from this clean-out downspout to clean out and then this snaps onto the dual wall pipe and over the single wall pipe.

It comes with our super sticky, super stretchy tape that is rated to last for 200 years so you can be sure that this doesn’t leak at the house at all. See video to learn where you want to put the tape. If you have any left, then at the far end on the end of the leach field pipe, the knife cut. You want to go ahead and pop the cone in. If you have any tape left, go ahead and secure that.

So, we have our turf restrictor plate with our pop-up and then we have a D box. You simply run this off the underground downspout, connect it to the solid, run the solid out 15 feet, connect it to the D box. Then come out the other side with the knife cut.

Remember all the bulk water is going to go through this knife cut, no problem. There’s no material ground out. Knife cut lives up to its name. It’s just a cut in a pipe, a solid pipe with some cuts. The bulk water is going to travel through this just fine, it’s going to make its way all the way to this pop-up emitter. We got the turf restrictor plate, so this will stop grass from growing over the pop-up. Because that’s number one problem, grass grows over anywhere you daylight your pipe, the outlet. Once the grass grows over it, the water can’t escape. That means the water builds up in the downspout and it just cascades over the gutter trough and ends up flooding your basement. Our turf restrictor plate solves this problem.

So, you got your solid pipe to get away from the house. You go to your D box. Then you go ahead to your knife cut, to your pop-up with a turf restrictor plate. All of this is a kit making buried downspouts easy for the DIYer and we can ship it small package.

How to Bury Downspouts – The Complete Guide for 2022

Shop Underground Downspout Kits and Do it Right the First Time!

We offer several buried downspout drainage kits depending on what you’re trying to accomplish in your yard.

Shop Buried Downspouts Complete Kit

Shop all Downspout Kits