Replies

1. 
   seres | Jul 16, 2009 02:54am | #1

   We form our own drains. I pour the bottom first, then build the sides out of plywood and attach them to the bottom with brackets. I attach a ledge or strip to the top outside of the form, to provide a recess or ledge for the grate. Remove the plywood and the brackets, and plaster the inside with waterproof cement.

   I think it is best not to embed angle iron in the concrete to form a ledge or recess for the grate. I’ve only used angle on one job, and over time the angle rusted and forced itself away from the concrete. A simple concrete ledge would have looked better over time.

1. 
   MNrosewood | Jul 16, 2009 04:43am | #3

   Thanks for the answer. I was concerned without the angle iron the slab would be chipped when the grates were pulled and replaced. The grates will probably only be pulled once a year though.

2. 
   WayneL5 | Jul 16, 2009 03:54am | #2

   We've done a lot of them and found several successful methods.  I have to say all have been indoors and not subject to salt or chemicals.

   If you need the trench to be waterproof the bottom and sides are done in a single pour.  Build plywood forms, with the sides atop the bottom piece, not the other way around, so the forms can be torn apart after the concrete has set.  Every couple of feet drill a 1" hole in the bottom.  The holes are an indicator that you have concrete under the bottom when some oozes up through the holes.  You have to use a vibrator when placing the concrete.

   If you don't need the trench completely waterproof you can pour the bottom first, separately, as the previous poster said.

   To prepare the angle, weld Nelson studs to the acute angle, bisecting the 90° angle, spaced every 18" or so.  These will head down and away from the angle, into the concrete at about a 45° angle when in place.  Weld all the angle together into a single frame.  Position and support it for the pour.  To keep the concrete from squeezing the trench angle together, use plywood pieces cut to fit snugly where the grating would go.  With the plywood thinner than the grating it doesn't stick up, allowing you to use the edge of the angle for a screed.  Remove and replace pieces as needed to check on the fill of the bottom of the form.

   If you don't have Nelson studs you can use regular hex head bolts, ungalvanized, 3/8" diameter by about 3" long.  Obviously the bolt is welded on the end opposite the head.

   Depending on how good it needs to look you can clean up and even apply a wash coat to the trench after the forms are removed.  By the way, we generally don't apply a release agent, finding it's not needed on such narrow boards.

   Sorry if I'm rambling a bit.  I have trouble dashing off a clear explanation on the first try.

1. 
   MNrosewood | Jul 16, 2009 04:49am | #4

   Does the form want float up out of the wet concrete?I also don't see how the top of the plywood channel connects to the inside lip of the angle iron.Thanks.

3. 
   dovetail97128 | Jul 16, 2009 05:52am | #5

   Done some pre-casts.
   Done some site built.
   I will take the pre-cast any day, but for as small as you are talking site built may be the way to go.

   Here is one manufacturer that has a pretty good product.
   http://www.acousa.com/drain/index.htm
   Good readable downloads on installation instructions and layouts, materials etc.
   Different price points, materials.
   I think you can find a single "catch basin" in their product line that may suit your needs, but certain you can find something.

   They can't get your Goat if you don't tell them where it is hidden.
1. 
   MNrosewood | Jul 16, 2009 02:14pm | #6

   Thanks.I was looking at the ACO Fastform. I'm calling this morning for pricing. I hope to use their cross sidewalk drain as well.