Saturday, April 10, 2021

Success: Passive Control of Radon in My Single-Family House

My House lies along the path of Missoula Floods erosion of land about 110,000 years ago, in a dramatic stage of erosion that formed The Columbia River Gorge,

Concentrated glacial deposits are associated  with higher concentration of radon release from soil.

The Oregon Health Authority warns of high radon levels in homes of East Portland:

For too many years of my life, I was aware of radon levels persistently above ten picocuries per liter in my home. EPA recommends: Fix your home if your radon level is 4 picocuries per liter (pCi/L) or higher.

A Citizen's Guide to Radon - US EPA

I have at last achieved the needed fix, by novel means employing the natural drive of chimney effect. I think this is a really big deal. By my example, every home could be fixed with modest up-front cost and without any operating cost or degraded home value by zip  code or neighborhood. This must be good news, not bad, for all of us, including abatement contractors. 


My quest for passive control of radon began with fitting two 4" warm air pipes sealed full-length, between my crawl space and my attic. There is excess space in a bathroom wet wall; put some of that to use. There will be significant chimney-effect drive of air flow when the pipe(s) are completed through-roof.

I expected to make this work someday, avoiding a radon pump if possible. How big is the needed pipe? Maybe 6" diameter?  The two 4" pipes equal one 6" pipe, and that much fits in the wall. If one is enough, the other might serve as an ample  wiring conduit between crawl space and attic. 

Minimize wet wall thickness above a tiled shelf. With an epoxied-on copper band, avoid reliance on caulk in sealing the new tub behind backer board and tile. Read more about the tub install in this blog post of October 2013: Insulate Exterior Wall of a Bathtub or Shower

For years then, the pipes did nothing, not connected through-roof and not collecting from the soil of the crawl space. House radon levels were unchanged.

(August 2019)

Dig this trench in the dry, hard dirt of my crawl space.

Hereafter I will own an over-abundance of these tubs. I disposed this many tubs of dirt, a carload, twice.

Use landscape cloth to separate collection ducting from the dirt.

The gravel fill is crushed quarter-minus.

At both bottom and top of 4" ducting, engage 4" warm air pipes with a spun-aluminum roof penetration adapter. In the crawl space the adapter flat face is upward. A wide circle of two-sided butyl tape bonds the adapter to the Americover Goldentouch 16 mm scrim-reinforced plastic sheeting, the central element of my conditioned crawlspace. On the roof, the adapter makes a better water barrier under an additional layer of shingles. A roof cap just blocks rainfall.

Here is another use of rope-form putty weatherstripping.

There has been a large binge of benefit from the clean ground cover for plumbing, wiring and heating of the grand kitchen remodel off in the far distance at left here. 

At last, it makes sense to complete the roof penetration  of the radon ducting.

Here are several months of observations by the renters of my house. Please see this report and other album pages that support and go beyond, the content of this blog post:

Stack-effect drive is proven to be ample in summertime conditions with a path having very small flow resistence.. At, find a calculator of natural draft, working whenever the outside temperature is less than temperature in the radon-suction stack, as occurring most of the time, through all seasons. In the calculator try a 6 meter closed-column height, and a temperature difference of 40 °C (-20 to +20°C)... Result: 0.4" wc.

A typical Fantech fan at noisy maximum power not-wanted, delivers 0.9" wc.

It is easy to see that natural drive should work

(April, 2021)

Work near the radon vent to add some ceiling LED lights in the living room.See that extensive flooring is an asset to ceiling access, not an obstacle.