Curtain drain in the crawl space – Part 3

Your basic plan sounds workable. I assume your crawl space is adjacent to a full basement area? I have a couple of questions. Where does the existing drain tile system empty? Is there a difference in level between existing basement floor and footings of the crawl space? the answers to these questions may change my answer to you. But basically, adding a French drain or perimeter drain tile should help your situation. After your trench is dug, be sure to line it with several inches of gravel/crushed stone. Use perforated pipe with inlet holes or slots on only one half of the surface and be sure the slots are facing up when installed. Wrap the pipe in common landscape cloth before backfilling with crushed stone to prevent the drain pipe from filling with sediment. Lay another layer of cloth over the stone and complete the backfill with clean grave. Not sure how you plan to connect to the basement drain system, but that is another topic. This kind of work is always difficult, especially when working in a crawl space with limited head room. Good luck.

OK Peter, next steps are easy compared to what you have done already. The first step is going to be install your foundation grade water proof insulation to the walls, from footer to the top. This comes typically in a sort of tongue and groove panel. Clean the excess dirt etc. off the walls and apply the mastic, then just stick the panels to the wall. Depending on what brand you buy, check with the supplier's recommendations for proper installation techniques. They are all pretty similar however. Since you are installing it in a crawl space on the inside of the wall instead of the outside, getting a complete water proofing layer of the mastic is not that important. I would highly discourage you from using the old spoils as backfill. You mentioned it was a clay base which is very poor for fast drainage. Please use the stone and gravel as I described in your last question. This method will assure you very good drainage. If you buy the drain tile (flex pipe) that is prewrapped, that will save some time and frustration. So, second step is to install your tile, and couple it through the foundation to your existing system. Complete your backfill, level out the area best you can then start your plastic vapor barrier. I would use a 6 mil minimum. Be sure to carefully tape all seams and neatly fit the plastic to the walls and tape it. The idea is to create a good vapor proof cell, keeping moisture out of the crawl space. You may consider some ventilation for summer season and closing said ventilation during the colder, dryer months. Sounds like you are well on your way. Don't short cut now, you got a lot invested. Good luck.