Replies

1. 
   fsmyles | May 09, 2022 04:30pm | #1

   "Contrary to popular opinion, the most effective method is to have the holes facing down."

   F

1. 
   sam40 | May 09, 2022 05:59pm | #4

   If the holes were facing down they would be blocked by clay

1. 
   fsmyles | May 10, 2022 10:01am | #6

   Drainage pipe should not be laid directly on soil, clay or anything other than 2"-4" of crushed stone. The errors you're making are common. Everyone makes them the first time and argue why they are right. Then they install the gravel and pipe with holes facing downward and have success and sleep better.

   Years ago when I was a laborer, we laid 6" of crushed stone in the trench, laid fabric on top of it and backfilled - no pipe. Worked well but wasn't a belt & suspenders approach and not a forever solution.

   Frankie

1. 
   sam40 | May 10, 2022 11:36am | #7

   I understand how to do it the way you'er talking about, and have used that for exterior drains before, but I don't want to lug crushed stone under there.

   All the water collecting in a wide ditch under there and so I put a small ditch with the pipe at the bottom of the large ditch and I think for this scenario(not necessarily most) that what I have is the best or at least easiest option once I find a way to hold it down.

   I'm thinking maybe rebar bent into an upside down U pounded in the ground to hold it down. Thoughts?

1. 
   ct_yankee | May 10, 2022 12:41pm | #9

   I understand that getting the stone in there is a challenge. There are less labor-intensive ways of accomplishing that but it may not be available to you.
   Try rotating the pipe so that the holes are on one side. Line the trench with filter fabric under the pipe and up the sides of the trench. Use some 4" wide concrete blocks (nominal 4x8x16) to weigh the pipe down. Leave some open space between the pipe's holes and the side of the fabric-lined trench.
   This doesn't do anything to hold down the humidity in the crawl space which should be a concern, but at least it's a step in the right direction.

2. 
   sam40 | May 10, 2022 03:58pm | #12

   To CT_Yankee
   Concrete blocks work I'm just looking for something smaller(or with a lower profile) so I don't risk puncturing the liner.

   I plan to install a liner and dehumidifier to deal with the ridiculous humidity under there.

   For some reason the site wont let me reply to your comment so I just replied to this one

3. 
   ct_yankee | May 10, 2022 08:24pm | #13

   Instead of concrete blocks, why not use patio blocks - they're about 2x12x12. If you're worried about the vapor barrier going over it, glue a piece of 1/2" foam insulation about 15" square to the top of the patio blocks.

4. 
   sam40 | May 11, 2022 08:20am | #14

   Great idea I will try that.

2. 
   ct_yankee | May 09, 2022 05:47pm | #2

   If you just laid the perforated pipe on the ground, what did you expect? You'd need to accumulate almost 4" of water depth before it would reach the holes. If you laid it in shallow trenches (say 4-5" deep) there would be little ballast to prevent it from floating. FSmyles is correct - the holes should be facing down AND there should be some amount of ballast over the pipe to offset any potential buoyancy.

1. 
   sam40 | May 09, 2022 05:58pm | #3

   Its half buried in the bottom of a large trench
   If the holes were facing down they would be blocked by clay

3. 
   unclemike42 | May 09, 2022 07:14pm | #5

   If you want to do it right, pick up the pipe.

   dig the trench deeper. line with fabric and some stones, then the perforated pipe, holes down. cover the pipe with more stones. try to have the pipe lay so water runs down hill to where you want to deal with it.

4. 
   sam40 | May 10, 2022 11:36am | #8

   I understand how to do it the way you'er talking about, and have used that for exterior drains before, but I don't want to lug crushed stone under there.

   All the water collecting in a wide ditch under there and so I put a small ditch with the pipe at the bottom of the large ditch and I think for this scenario(not necessarily most) that what I have is the best or at least easiest option once I find a way to hold it down.

   I'm thinking maybe rebar bent into an upside down U pounded in the ground to hold it down. Thoughts?

1. 
   unclemike42 | May 10, 2022 03:38pm | #10

   I would go with two, pounded in at angles above the pipe. no need, but you could tie them together if you like. Kind of like an x with long legs buried, top only has to hold the pipe.

   You can calculate how much the pipe full or water would weigh, and that is how much force you need to account for in the floating direction for an empty pipe.

1. 
   sam40 | May 10, 2022 03:50pm | #11

   Ok I will probably bend the ends over the pipe so is doesn't puncture the vapor barrier

1. 
   unclemike42 | May 11, 2022 04:48pm | #15

   You can also put caps on the end and drive until they are almost flush with the pipe. (or drive them in and then put caps on)

   I bet you could use an air chisel to get them where you want them. Or an SDS hammer drill with a ground stake driver.

   Always better with tools, and they look good on the shelf when the job is done.

1. 
   sam40 | May 11, 2022 07:23pm | #16

   This is a good idea and would certainly work but the pavers CT_Yankee suggested are cheaper
   $6.32* for 4 pavers and (I already have the foam on hand)
   vs
   $17.04* for rebar, $12.34* for caps, and $44.55 for ground rod driver

   I wonder why the pavers are so cheep

   * Prices from lowes.com

5. 
   unclemike42 | May 12, 2022 08:50am | #17

   As I suggested before, do a little math and make sure the weight of the blocks you use for ballast exceed the weight of the displaced water an empty pipe will exert upwards.

   4 inch pvc pipe is 4.5 inches OD, radius of 2.25 inches or 0.1875 ft. . area is r**2 times Pi. Call it 0.11 square feet. Water is a little over 64 pounds per cubic foot. so you will need to apply over 7.2 pounds per foot of pipe to make sure it will not float.

   weigh one of your patio blocks dry to see how many you need. If the weight is not only on the pipe, you will need more of them.