Installation: Drainage & Vapour Barrier

We’re finally getting around to sorting through paperwork from the 2018 summer build season. I thought it might be interesting to share photos of the installation of the vapour barrier and drainage system.

I know is some areas water (and therefore drainage) is not as much of an issue as it is for theDoighouse. We are located in a Coastal Rainforest with annual average rainfall of 872.11 mm in 2018.

The township of Bowser is the closest weather reporting. Here’s a glimpse at our average rainfall pattern. NOTE: this does not include annual snowfall.

Average Rainfall in Bowser

In many earthship build locations water is not as much of an issue as it is for theDoighouse. Along with the rainfall, our water table is quite high.

What you see here is the methodology we need to follow in order to meet the building code requirements for the Regional District of Nanaimo, BC. It may be different in your location.

Vapour Barrier Methodology

The tires were placed on compacted undisturbed soil following the layout of the string lines outlined in inspection #1 – Base Prep. A thorough check was made against the drawings. Section by section we moved the tires and placed 10mil Poly vapour barrier under before replacing the tires.

We assured that a 12 inch overlap could be maintained on all overlap joints For each overlap we placed a double row of acoustical sealant as specified on the drawings. We ensured that this double row closed the route of all ingress of moisture into the conditioned space. The pictures show both the pattern of sealant and the 12 overlap allowance. The overlap will be maintained as it follows the exterior of the tire wall both with sealant and approved tape.

Drainage Methodology

The methodology was to locate 4″ perforated drainpipe adjacent to the lowest course of tires (considered the footings) and on top of the insulation board. The pipe was laid on filter cloth and drain rock forming a tube.

Standing cleanouts were installed at the furthest most point from the drain and midpoint along the rear wall.

The same methodology was repeated at the base of the vertical insulation 4 ft out from the tirewall. These two drains were connected at each end of the rear wall to continue around each end of the house (east at garage and west at greenhouse. the pipe was installed with a slope 15″ over the length of the run.

The following are a series of photos taken during the installation of both the drain at the base of the tire wall and at the base of the out-board insulation.  

Drainage completed and backfilled to course 6

Can’t wait for the snow to go so we can unwrap theDoighouse and get back to pounding tires.

If you’re looking for a chance to hang out and help, we are always looking for people interested in learning about Earthship building, community gardens, and food forests! Email susanmdoig@gmail.com if you want to know more.

Or join us for our monthly fireside@theDoighouse chat connecting professional builders, enthusiasts and individuals curious and/or passionate about natural building. If that sounds like you, or someone you know, we meet the 3rd Tuesday of each month.

NOTE: 6:00pm start time – come a little early, stay a little late!

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