The crawl space

One of the major projects we’ve worked on since living in this house on Camden Sugar Valley Rd is the crawl space. I had never really lived in a house with a crawl space. And, had only been in one a time or two. In my¬†continuing¬†interest of learning how things are built, I was really into the idea of improving the crawl space. By the end of the project(s), I was sick of the crawl space.

Having thought about it for a few months, though, I do like the idea of a crawl space. They just need to be done right. It allows you to do all kinds of things you can’t with a slab or even a basement. Repairs are easier. And, if the space is done right, it can serve as long term storage.

Here’s a basic list of what was wrong:

  • Drainage problems around house
  • Incomplete vapor barrier on crawl space floor
  • Air conditioner condensate drain not properly plumbed
  • Rear deck installed without flashing of any kind
  • So-called crawl space vents inadequate

The house and surrounding property suffer from the typical “false water table.” This is where the backfill next to the house is not as compacted as the undisturbed soil both underneath and farther away from the house. The water quickly percolates through this semi-compacted backfill (which also usually contains a lot of gravel) and hits the undisturbed and more compacted sub-soil. If there is enough water, it accumulates because the clay soil we have doesn’t let water drain very well. This problem is made far worse if the grade around the house is incorrect. And, even worse if your house is down slope from higher ground.

One side of the house we completely re-graded as it was positively sloping towards the house. And, had a flagstone pathway directly touching the house. This stone pathway shed loads of water right at the foundation. We took up the stone pathway and regraded the area to drain away from the house.

We also installed a partial perimeter drain around the wettest sides of the house and installed a sump basin and sump pump in the lowest spot in the crawl space. This was a major pain. Even though we really only had to dig down at most 6″ to get to the bottom or below the footer – try digging in hard clay with only 3 feet of clearance. This was much more difficult than I had imagined. But, the drain and sump work really well.

On my very first inspection of the crawlspace, I simply dug through the 3-5 inches of pea gravel to see what was underneath. Some places I found a black vapor barrier. Some places I did not. Where I didn’t I dug until I found it. Sometimes it was 3 feet away from where it needed to be. An incomplete vapor barrier is almost as bad as not having one at all. Vapor rises absolutely from the uncovered areas.

The other problem with the vapor barrier had to do with the air conditioner. Whoever installed the A/C plumbed the condensate drain straight down, not outside like it should have been. Or, at the very least, they should cut away the vapor barrier so the condensate didn’t collect and spread out on the vapor barrier. After we finally got the A/C in working order (that’s another story) we, of course, ran the unit. After about a week I checked it out. There was a wet pea gravel area at least 20 feet in diameter. This was obviously bad and contributed greatly to the moisture problems. I re-plumbed the drain into the sump we had installed.

Not long after that inspection, I started researching what to do with a problem crawl space. The short version is this: we did what we could on the outside, solving drainage problems, plumbing downspouts well away from the house (so they don’t dump water into that false water tabe). Then we removed the inadequate vents – closed them off with concrete blocks. Installed the drain and sump. Re-raked all of the pea gravel smooth and so it covered the footer. The raking was done so the vapor barrier wasn’t resting on a hard, rough concrete edge. After all of that was done, we lined the crawl space with 8 and 12-mil fiber reinforced vapor barrier. 8-mil was used on the walls – we ran the barrier all the way to within an inch of the top of the concrete block knee wall. 12-mil was used on the floor. I’ll post pictures of the final next.

One day, while we were finishing putting the liner down, it was pouring down rain. Not a big deal – we were in the dry crawl space! However, I noticed some water trickling in around the rim joist and wondered how that was getting there. Oddly enough, it was coming from an area along where the rear deck was installed. The next time we had a day where it was sunny, we pulled back the siding above the deck to see anything obvious. We found no flashing of any kind. And, found rotten wood in the exterior wall all along the deck. Whoops. The water was essentially hitting the deck and siding and seeping either behind the ledger board or down and collecting on the concrete block and sitting next to the rim joist. All in all, not good. So, we pulled up every single deck board and installed flashing to keep the water from seeping into the crawl space ever time it rained.

Anyway. I was originally going to just post a few pics with a little explanation. Once I got into it, I remembered what a big job it was. So, I did a quick and dirty run down. Maybe I’ll post more in the future. Here’s the pics: