While the trench was open, it was our chance to lay the drain tile and earth tubes. We didn’t set the timelapse and we were too busy working to take many photos, but it is an important step for any earth sheltered home, so I want to capture a few details. Sorry, no timelapse.
We had already laid the drain tile and earth tube close to the house as we back-filled that portion. Click here for that story. But we still needed to run long tubes from the house to daylight.
The bottom of the trench was already sloped to 1% and the septic line, made of 4″ schedule 40 PVC, was already in place (done by the excavator and already approved by the plumbing inspector). We needed to bury it, but with a constant slope. Sherri and I used shovels and rakes to pull down dirt and bury the original line by about 6 inches. We (and the boys) stomped on this layer to pack it down, especially next to the buried septic pipe. The end result was a nicely sloped flat bottom trench.
We connected 100 ft long segments of 6″ corrugated drain pipe to the ends of the pipe we had already buried up by the house. We used a proper fitting connector piece and also taped it heavily and covered the connection in landscapers fabric. We laid these two parallel drain tiles along the trench and periodically placed dirt on them to even everything out and keep them separated by a couple feet. I would have liked to have separated them by more, and I did where the trench was wide enough. In all, we added about 150 ft of pipe to each end of the drain tile loop.
Normally, a drain tile loop is connected to a single long pipe that runs to daylight. However, by connecting each end to its own pipe, I am able to use it as an earth tube circuit with an inlet and outlet or two inlets. The other end of the pipes goes into the house, but I can simply connect those ends together if I want the air to circulate under the mass of the house without entering it (by-passive annual solar heating). The extra cost is the additional 150 ft of pipe, which cost me about ~$100.
The second layer of earth tubes was the 8 inch double wall (smooth inside) HDPE pipes. These come in straight 20ft segments that have a bit of flex to them. You can connect the pipes directly (bell and spigot ends with soil tight connectors) or you can connect them with 30 or 45 degree joints. It was a hot day and we did not have the energy to properly bury the 6″ corrugated drain tile before laying the larger earth tubes, so we decided to mount the larger earth tubes to the side of the slope (with stakes) a couple feet above the previous layer. This still left more than 10 ft of earth above these pipes for most of the distance and gave us more than 6 ft between the two parallel pipes.
At the end of the day, we had 4 earth tubes, each over 150 ft long, going from the house to “daylight” along the trench.
The next step would be backfilling.
Later, while back-filling the trench, we made sure that the 8 inch pipes stayed in place while the excavator back-filled below/between them and the 6″ pipes… This took some care and probably added at least an hour to the back filling process. The excavators charged by the hour, so that should probably be counted in the cost of the earth tubes, but seemed like a bargain compared to backfilling that trench manually on that hot day. I did pull out some of the stakes when they were no longer needed to hold the pipe still, but many were buried in place at an additional cost.
Before we can back-fill against the basement, we needed to clear the area, waterproof and put in the drain tile… We also needed things like radon tubes and floor drains to exit the building.
My wife, Sherri, had to help a lot this week… And as she puts it, “It wasn’t princess work!” I did try to hire some people, especially when I realized I would have to carry down and place the 4 yards of pea stone by bucket, but it didn’t work out and we were on our own.
The video is here…
Stripping
I started with stripping the bracing away. In most cases the wood was perfectly good with only a few screw holes. I will get to use it all again on the second floor. Actually, the site has only generated a couple bags of garbage and a box for recycling all summer, and that was mostly lunch trash dropped by the contractors working on the site.
I left the insulation on the side of the window well. It was meant to be forming, but with an earth sheltered umbrella, it helps to insulate the earth where ever you can.
Waterproofing
We bought a power sprayer from home Depot (Graco Magnum X7), which worked pretty well. We justified the purchase by reminding ourselves how much work it had been to paint the ceilings in our current house when we moved in. This sprayer will come in handy when we do one last paint before we put our existing house on the market next spring. As for the current task of spraying on the waterproofing, we saved a lot of time (and got better coverage) by not trying to roll the water proofing over that rough surface. With only one sprayer, it was a one person job and Sherri took care of it.
As for the water proofing its self, we used ProteShield Elastomeric Waterproofing Sealer. We actually applied it about 50% thicker than the directions specified. The instructions said it would dry clear, but we were surprised that it appeared to “disappear” after just a few minutes (and faster on smoother sections of the wall). It was like it wasn’t even there.
When we got the waterproofing inspected later, the building inspector was concerned about it. He gave us a “partial” pass, and told us we could proceed at our own risk, but if the waterproofing doesn’t qualify, we will need to dig it up and do it over again. We proceeded with the back-filling on faith in Home Depot and (later that evening) sent him this technical data sheet, which mentions that it is for above and below grade waterproofing of basements and foundations. It even says to give it 48 hours to cure before back-filling, we gave it double that. However, the inspector says it is missing a mention of some specific government tests that would qualify the waterproofing for use as below grade waterproofing. The inspector is going to try and contact the company to see if they have this documentation, and if not, he is going to insist that we redo it.
Drain tile
I suppose drain tile used to be made of ceramic tiles curved into tubes and then fired. In hispanic areas, I have seen them use the same tiles they use on the roofs. These were placed end to end to help carry water away from foundations. Now days, they are made of HDPE plastic that lasts forever. Ours was also covered in a nylon sock to keep the sand from clogging it.
Actually, our site doesn’t even really need drain tile. The sand just lets the water fall thru it, but the building code says we need it and that we need it to be covered in pea stone (an extra cost/hassle that shouldn’t be necessary for such a sandy site).
Another neighbor in the area told me that he put in the drain tile around his house to satisfy the inspection, but then didn’t actually run it to anywhere, since that part is not actually inspected.
I agree that these drains will probably never carry water, but I decided they should at least do something. I am going to use them as earth tubes to carry fresh air into the house. Sherri doesn’t like the idea of carrying fresh air thru corrugated pipes because water can sit in them and cause problems (mold, humidity)… But I also know of many success stories. I wanted to try it out and I can always seal them up if it doesn’t work out.
The first day that we laid the drain tile, the battery died in the camera, so you don’t see how many hours it took me to get it all sloping just right.
The big hassle on the second day (Saturday) was carrying all that pea stone down into the “pit”, bucket by bucket. We didn’t make our Saturday night deadline. The inspector is only available for a few slots each week, so if we missed Monday for the pre-backfill inspection, we would need to put off the back-filling and schedule the inspector for Wednesday…
That was the the day my sister was coming into town… We would need to come back and finish up then.
Insulation
You can’t see it in the video because Nick and I were working on the other side of the basement. We initially hoped that the waterproofing would be sticky enough to “glue” it, but it was not sticky at all. So we waited for the waterproofing to dry (2 hours cure time), and then tried to glue 2 inch thick Foamular 250 to the walls using “Liquid Nails“… That didn’t work out at all because we couldn’t keep the stiff foam pressed against the curved wall long enough for the liquid nails to dry. We decided to add the insulation as we back-filled… The dirt will hold it in place very well.
