Radon Mitigation in Dugald

Dugald and the surrounding countryside in the RM of Springfield present a rural version of the same clay problem found across the region, with an agricultural twist: much of the local drainage is managed by field ditches and municipal drains, and how those perform directly affects residential crawlspaces. A blocked or overtopped drain in a wet spring raises the local water table, and homes with shallow crawlspaces feel it first. Several properties we have worked on took water not from rainfall but from a drainage system that could not move melt fast enough.

Housing here ranges from century-old farmhouses to modern acreage builds. The older stock often has partially excavated crawlspaces with soil floors, timber or rubble foundation elements, and generations of informal repair — posts set on patio slabs, beams sistered with whatever was available, vents cut and later blocked. These spaces usually show the full sequence of moisture damage: efflorescence on walls, rust on hardware, mould on joists and soft sheathing under bathrooms and entries. Newer builds are tighter but frequently have an unheated crawlspace under part of the footprint that was never properly air sealed.

We treat rural crawlspaces as systems that have to survive without anyone checking on them. That means mechanically fastened and sealed barriers rather than loose poly, sump pumps with reliable power and freeze-resistant discharge, dehumidification sized for the actual volume, and insulation that protects well lines and plumbing at minus 30. We document moisture content in the framing before and after so there is a baseline, and we flag anything structural — a sagging beam, an undersized pier, a rotted sill — before it becomes an emergency in the middle of winter.

Calls from the Dugald area frequently trace back to drainage infrastructure rather than rainfall. A municipal drain or field ditch that cannot move melt fast enough raises the local water table, and homes with shallow crawlspaces feel it first. The other recurring call is from owners of older farmhouses who have finally gone into a crawlspace they had never entered and found soil floors, generations of improvised repair, and framing that has been damp for decades.

Rural crawlspaces have to run unattended, and that shapes how we specify them. Equipment that depends on someone checking it weekly will fail, because nobody checks a crawlspace weekly. So: sumps with reliable power and freeze-resistant discharge, dehumidifiers with permanent drains rather than buckets, barriers mechanically fastened rather than loose, and a high-water alarm where a failure would cause real damage. A system that can report its own status is worth considerably more on a rural property than a marginally better pump.

Our first recommendation for a Dugald-area property is usually to establish the local drainage context alongside the crawlspace inspection — where the nearest drain runs, how it performed in the last significant melt, and whether the lot's grading moves water toward or away from the house. On agricultural land that context frequently explains a crawlspace water problem that looks inexplicable from the building alone.

Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock. It is colourless and odourless, it moves upward through soil, and it enters buildings through any opening in contact with the ground. Health Canada identifies it as the second leading cause of lung cancer after smoking, and sets a guideline of 200 becquerels per cubic metre for indoor air, recommending remedial action above that level. Manitoba consistently records some of the highest residential readings in Canada, which makes this a local issue rather than an abstract one.

A crawlspace is the most efficient radon entry point a house can have. Where there is exposed soil, or a thin unsealed membrane, soil gas moves into the space essentially unimpeded — and from there into the living area, because the stack effect pulls air upward through a house continuously during the heating season. Our long heating season means that pressure difference operates for a large part of the year. A house with a sealed basement slab but an open crawlspace under an addition can still have substantially elevated levels.

Testing has to come before mitigation, and it has to be done correctly. A long-term test of at least three months, ideally during the heating season when windows are closed and the stack effect is strongest, gives a representative result. Short-term tests are useful as a screening indicator but fluctuate too much to base a decision on. We will arrange or guide testing, and we would rather you test first than buy a mitigation system you may not need — though in a crawlspace with exposed soil, sealing the floor is worthwhile on moisture grounds regardless of the radon number.

Where mitigation is needed, the standard approach in a crawlspace is active sub-membrane depressurization. A sealed membrane is installed across the floor and up the walls — the same membrane used for encapsulation, which is why these two projects belong together — and a dedicated fan draws continuously from beneath it through a perforated collection pipe, venting above the roofline. That negative pressure under the membrane captures soil gas before it can enter the space. The system is simple and highly effective, but it depends entirely on how well the membrane is sealed, which is why installation quality matters more than equipment selection.

Post-mitigation verification is not optional in our view. After the system is running and the building has returned to normal operating conditions, the space and the living area should be retested to confirm the reduction. We also label the system, explain what the manometer reading means, and tell you what to check — because a mitigation fan is a mechanical device that will eventually fail, usually silently. A system nobody monitors is a system that may have stopped protecting you years ago.

Pressure and building dynamics explain why two apparently identical houses can test very differently, and why your neighbour's result tells you nothing about yours. Radon entry depends on the pressure difference between the soil and the building interior, and that depends on stack effect strength, exhaust appliances, mechanical ventilation balance, wind, and how tight the building is. A house with powerful kitchen and bathroom exhaust and no make-up air runs at a greater negative pressure, and draws correspondingly more soil gas. This is also why sealing work and mechanical changes can shift a reading in either direction, and why testing after any significant envelope work is sensible.

System design details separate a mitigation that works from one that merely hums. The collection point beneath the membrane needs a permeable layer — clean gravel or a drainage mat — so the fan can draw from the whole footprint rather than a single spot. The fan has to be sized to the soil's permeability and the area served: too little suction leaves parts of the footprint uncaptured, too much wastes energy and can pull conditioned air if the membrane has gaps. The exhaust must terminate above the roofline and away from windows and air intakes. And the pipe needs a manometer, so the system reports its own status.

Timing relative to encapsulation is the practical advice we give most often. If you are sealing a crawlspace for moisture reasons and you have not tested for radon, test first. The collection pipe and gravel layer belong under the membrane, installed before it goes down; retrofitting them means cutting open a barrier you just paid for and compromising its continuity. A long-term test takes three months, which is usually compatible with planning a project anyway. If the number comes back low, you have lost nothing but gained a documented baseline. If it comes back high, you have saved yourself from doing the job twice.