Radon mitigation in Cambridge, stone basements included.
South West Radon installs C-NRPP certified radon systems across Galt, Preston and Hespeler, including the rubble stone foundations most contractors will not touch. Guaranteed below 75 Bq/m3 and verified with a post-install test. Protecting homes. Protecting health.
You have the number. We are the fix.
Most people reach us after a test comes back over Health Canada's 200 Bq/m3, or after a neighbour's did. You do not need to wade through the science or wait on another round of testing to get moving. You need it fixed, verified, and off your mind, and that is the entire job.
You already tested
Bring us the number. We design the system to your result and your Cambridge home, and the post-install test proves where you finished.
Your neighbour tested
Same soil and the same era of construction, but radon varies house to house. A high result next door is a real reason to act, not a guarantee your home is also high. Our guarantee is an absolute number rather than a percentage reduction, so it still means something without a "before" reading: the post-install test shows exactly where your home has landed.
You are buying or selling
A radon result on a conditional does not have to derail the deal. We handle the fix and give you the documentation the transaction needs.
Why does radon matter in Cambridge?
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Radon is the leading cause of lung cancer among non-smokers, and the second leading cause of lung cancer overall, after smoking.
Roughly 16% of lung cancer deaths in Canada are linked to indoor radon exposure.
Bq/m3 is the level at which Health Canada recommends taking action. The WHO suggests a stricter 100 Bq/m3.
References: Health Canada, Radon · Take Action on Radon. Last updated August 2026.
Why is radon harder to fix in a Cambridge century home?
Because a standard system assumes a poured concrete slab, and many of the oldest homes in Cambridge do not have one. Galt was founded in 1816 by Scottish settlers and largely rebuilt in stone after the fires of 1851 and 1856, so the historic cores hold a great deal of rubble stone and fieldstone foundation housing. Those basements are porous, uneven and often only partly floored. They need a different method, not a refusal.
Rubble stone walls are not the starting point
A fieldstone wall is not a sealed surface, and we do not try to make it one. Soil gas enters through the joints across the whole wall, so the fix is to depressurize the slab beneath it, not to seal the masonry.
No continuous slab to work under
Sub-slab depressurization needs a slab to depressurize. Where the floor is partial, dirt or fieldstone, that approach has nothing to pull against.
More than 660 heritage properties
The Cambridge heritage register lists over 660 properties. This is not a rare edge case here, it is a large share of the housing in the old cores.
Stone basements and crawl spaces: the real approach
Stone basements in Cambridge are not a dead end. Most have a thin concrete mortar slab we can work with, patching rough areas with concrete topper before the system goes in. Crawl spaces are a different story, and we are honest about that up front.
Stone basements: work with what is there
Most century stone basements have enough of a concrete mortar floor to work with. We patch rough areas with concrete topper, then install the suction system topically, positioned toward the middle of the floor rather than against the fieldstone walls. Pulling from the slab is almost always enough to bring levels down to where they need to be.
Crawl spaces: treat the slab first, test, then decide
We treat the slabbed area first, then test the result. In many homes that is enough. If the numbers are not where they need to be, we address the crawl space in a second phase. We never do crawl space work speculatively, because it more than doubles the cost and often turns out to be unnecessary.
Crawl space work costs more, and we say so
When a crawl space does need to be mitigated, we dig a deeper suction pit, upsize the fan, and seal a heavy poly membrane across the earth floor. It is more labour, more material, and the total job can reach $7,500 to $8,000. You will know that number before we start anything, not after.
How much does radon mitigation cost in Cambridge?
Most residential systems run about $3,200 to $4,000, and a straightforward Cambridge home with a poured slab sits in that range. An older Galt or Preston house with a rubble foundation, a partial floor or multiple basement levels takes more membrane, more sealing and more labour, so it can run higher. You get a firm written number before anything starts.
Poured slab, modern home
A standard sub-slab system, one suction point, installed in a day. This is the typical $3,200 to $4,000 job across Cambridge.
Stone foundation or crawl space
A sub-membrane system costs more because it is more work: membrane, full sealing and sometimes more than one suction point. We quote it honestly up front.
Never a surprise
We assess the actual basement before quoting. The price you agree to is the price you pay, and the guarantee does not change with the difficulty of the house.
What is the site inspection?
It is a paid, educational walkthrough of your home with a C-NRPP certified professional. We look at your foundation, your test result and the routes radon is actually using, explain your options in plain language, and leave you with a firm written price. If you go ahead with the mitigation, the inspection fee is credited back in full against the job.
An assessment, not a sales call
You get a certified professional's time and a proper look at your Cambridge home. Nobody is there to pressure you, and you keep what you learn either way.
Credited back in full
Proceed with the work and the fee comes straight off the price of your mitigation, so the inspection ends up costing you nothing.
You leave with a firm price
Not a range and not a guess. A written number for your specific home, so you can make the decision on real information. Note: the quoted price is based on what we find during the site inspection. In the rare case that diagnostic tests on-site reveal additional scope, we will explain the change and give you an updated written price before any work begins.
What makes a South West Radon system different?
Two systems can both move radon and still be very different to live with. We design for what happens after we leave: whether your sump stays serviceable, how loud the fan is in your living space, and whether you can get ahold of us if something needs attention.
Your sump pump stays fully serviceable
We cap sump pits with a dome that lets you get at the pump without dismantling the radon system. A failing sump is an emergency, and the last thing you should be doing is taking a radon system apart to reach it.
Designed for noise, not just radon
Every system gets designed twice: once to move the radon, once to stay quiet. Fan sizing follows from the ambient pressure calculations. Get those wrong and you get a system that is louder than it needs to be, works harder than it should, and costs you more in the long run: a larger fan draws more electricity, and the stronger suction pulls more conditioned air out of your home with it (the energy penalty). The difference between a correctly sized #1 fan and an oversized #4 fan can mean roughly $20 a year versus $180 a year to run. Over 10 to 15 years, that adds up.
You get a person, and a fast one
Response time is a service standard here rather than an afterthought. Radon questions tend to arrive with a deadline attached, whether that is a sale closing or a family worried about a result.
Maintenance free, and that is deliberate
The system is designed so you can forget it exists. Nothing to service, nothing to empty, nothing to book. The fan is the only part with a service life, which is exactly why we specify a good one instead of the cheapest that meets spec, and swapping one is a simple job.
A certified partner, not a handyman with a fan
Radon work is health work, and the only proof it worked is a measured number. We are certified under the Canadian National Radon Proficiency Program, we carry substantial liability and pollution insurance, and we put the guarantee in writing before we start.
C-NRPP certified and fully insured
We are certified under the Canadian National Radon Proficiency Program and carry substantial liability and pollution insurance, so the job is done to standard and you are protected.
A guarantee with a real number
We do not say "improved air quality" and hope. We commit in writing to below 75 Bq/m3, far under Health Canada's 200 limit, and we prove it with a post-install test.
Local to Cambridge and the region
We live and work here. We know the housing stock, the soil, and why Cambridge basements test the way they do, and we are minutes away, not hours.
Systems built to last the life of the home
Once the pipe and system are in there is almost nothing to maintain except the fan years down the road. It is a one-time fix for permanent peace of mind.
From radon number to a safe home in four steps
You want it fixed
Your test came back high, a neighbour's did, or a sale depends on it. Call us with your number, or without one.
Site inspection
A paid, educational walkthrough of your home with a certified professional. You get your options explained and a firm written price, and the fee is credited back in full if you proceed.
One-day install
A typical residential system goes in within a day, clean and tidy, with the vent routed properly to the exterior.
Verified below the limit
We run a post-install test and hand you the reading that proves where your home landed.
Radon mitigation across Cambridge, Galt, Preston and Hespeler
Cambridge was formed on January 1, 1973 from Galt, Preston, Hespeler and part of the surrounding townships, and each core has its own housing stock and its own radon challenges. We work in all of them.
- Galt
- West Galt
- East Galt
- Preston
- Hespeler
- Blair
- Clemens Mills
- Southwood
- Shades Mills
- Elgin Park
- Branchton
- North Dumfries
- Ayr
- Roseville
Reviews from real Cambridge area customers
These are unedited Google reviews from homeowners we have worked with. Nothing here is written by us.
We recently moved to a new place, and decided to do radon mitigation after a few months of testing. We've had several other contractors through in the past few months, and South West Radon was by far the best experience overall. The entire process with South West Radon was outstanding. Phil took the time to do a thorough visit and consultation, explaining the options, steps, showed us examples of different units, noise level, etc., without any feeling of upselling or pushing. During the install, we discovered an issue with the layout of our home that required a modified plan, and they offered us several alternatives. Installation was quick, professional, and competitively priced. We've done continued testing and our radon levels have absolutely plummeted, and are comparable with outdoor ambient levels, with virtually no negatives like noise.
HillsideGoogle reviewWe have been so pleased with our decision to have contracted Phil and his team to complete our Radon Mitigation. Right from the start it was apparent that we were dealing with a knowledgeable professional that had all of the attributes of the ideal contractor. Phil provided a description of every step of the process necessary, answered all questions prior, during and after the job. On installation day he and his crew treated our home as if it was their own and made sure the job was done effectively and neatly. Our readings improved within hours of completion.
Dino GuerraGoogle reviewPhil and Dennis did a great job on our radon mitigation system installation. We really appreciated their professionalism and attention to detail throughout the job. Phil was a delight to work with right from the start, always having time for our questions and going the extra mile to ensure the system was as quiet and unobtrusive as possible. We couldn't be happier with the process or the end result, drastically reduced radon levels and a mitigation system so quiet we hardly notice its there.
Trudi CollinsGoogle reviewRadon mitigation FAQ
Can radon be fixed in a house with a stone or rubble foundation?
Yes. Century homes in Galt, Preston and Hespeler are mitigated all the time, they just need the right method. Where there is no continuous poured slab we install a sealed sub-membrane system, drawing the radon from beneath a membrane bonded to the foundation walls. The guarantee is the same: below 75 Bq/m3, confirmed by a post-install test.
Why do you charge for a site inspection?
Because it is a real assessment by a C-NRPP certified professional rather than a sales visit. You get a paid, educational walkthrough of your home, an explanation of your options, and a firm written price for the work. If you go ahead with the mitigation, the inspection fee is credited back in full against the job, so it ends up costing you nothing.
Do I need to test before you can fix it?
No. Most people come to us with a result already in hand and that is the most direct route, but you do not have to wait for one. Plenty of homeowners mitigate because a neighbour tested high, or simply because they want the protection in place. Because our guarantee is an absolute number rather than a percentage reduction, it still means something without a "before" reading: the post-install test shows exactly where your home has landed.
Will the system need maintenance?
Almost none, and that is deliberate. The system is designed so you can forget about it: there is nothing to service, nothing to empty and nothing to schedule. The fan is the only component with a service life, which is why we specify a good quality one rather than the cheapest that meets spec. If one ever does fail it is a straightforward replacement. We suggest retesting every couple of years or after major renovations, simply because that is good practice.
Does a dirt floor basement or crawl space need a different system?
Yes. A dirt floor or crawl space cannot be depressurized the way a slab can. We lay and seal a heavy membrane across the earth, bond it to the walls, and place the suction point underneath it. This is standard C-NRPP practice and it works well in older Cambridge homes.
How much does radon mitigation cost in Cambridge?
Most residential radon mitigation systems run about $3,200 to $4,000. A century home with a rubble stone foundation, a partial or earth floor, or multiple basement levels takes more sealing and more membrane, so it can be higher. You always get a firm written quote before any work begins.
Will the work damage a heritage home?
No. We plan pipe routing and suction points around the character of the house and keep the visible work to a minimum. Nothing structural or historic is altered to make the installation easier. If a route would be intrusive, we find another one.
What radon level is considered safe?
Health Canada recommends taking action to reduce radon when the level is above 200 Bq/m3, and the World Health Organization suggests a stricter reference level of 100 Bq/m3. We design every system to bring your home below 75 Bq/m3, well under both, so you have real margin.
How long does the installation take?
A typical residential system is installed in a single day. A large sub-membrane system in a century home can take longer. We then run a post-install radon test, a minimum of three days, to verify your home is below the 75 Bq/m3 guarantee.
Do you guarantee the radon level will drop?
Yes. We guarantee your home will measure below 75 Bq/m3 after mitigation, or as low as reasonably achievable (ALARA) in the rare case that a building restriction physically prevents reaching that number. It is confirmed by a post-install verification test. The guarantee does not change because the house is old or difficult.
Book your Cambridge site inspection
Tell us a bit about your home and your radon result, and we will book your site inspection: a paid, educational walkthrough with a C-NRPP certified professional, your options explained, and a firm written price. The fee is credited back in full if you proceed. Prefer to talk now? Call (519) 807-1995.
Book my site inspection
We reply the same day, most days.
An old house can still have safe air.
Stone foundation, crawl space or new build, there is a system that fits it. Let us get your number below the limit.