A radon mitigation system gives the gas a way out of your house that is not through your living space. Pipe, fan, sealed entry points, and a way to confirm it is working. If you have a test result in hand and you are in Nashua, we can look at it.
What radon actually is, without the scare
Radon is a gas that comes up out of the ground and gets into houses through the lowest level. You cannot smell it or see it. At high enough levels over long enough it is genuinely bad for you, which is why testing exists.
The reason we lead with testing rather than selling: your neighbour’s number is not your number. Houses fifty feet apart test differently. Get your own.
How the system works
The common approach is sub-slab depressurization. We core the slab, put a pipe into the material under it, run that pipe out and up, and put a fan on it. The fan pulls a slight vacuum under the slab so the gas goes up the pipe instead of into the basement. Then we seal the obvious entry points, the floor wall joint and any open sump, so the system is pulling from under the slab and not from your basement air.
Crawl spaces work a bit differently. The membrane becomes part of the system and we draw from underneath it.
Testing before and after
We test, we install, we test again. That second test is the whole point, and you should insist on it from anyone you hire.
603 holds a state radon measurement certification, RMS-113966.
What we will not promise you
We will not guarantee a specific radon number unless we put that number in writing for your house.
Plenty of outfits will promise you a level over the phone. We would rather test your house, install the system, test again, and show you where it actually landed. If a specific result matters to you, and for a real estate closing it usually does, get it in writing before the work starts. From us or from anybody else.
The warranty
Radon mitigation carries a 10 year warranty on system integrity and components. That covers the system. It is not a guarantee of a radon level, for the reason above.
Questions we get
My house is new. Do I still need to test?
Yes. Construction age does not tell you what is under the slab.
Is the fan loud?
You should hear a low hum at most. If a system is noisy or rattling, something is wrong with it and it is worth a call.
Does it run all the time?
Yes, continuously. Turning it off means it is not doing anything.
What about radon in water?
That is a separate test and a separate system from the air side. If you are on a private well it is worth asking about.
I am selling. How fast can this happen?
Tell us the closing date when you call. Most installs are a day.
Reading your test result
| Situation | What it means | What happens next |
|---|---|---|
| Short-term test came back high | A snapshot, and worth acting on | Confirm, then look at the house for a system layout |
| Two tests disagree | Normal. Radon moves with weather and season | Longer test, or treat the higher reading as the planning number |
| Buyer or seller needs a number | There is a deadline attached | Tell us the closing date when you call |
| Finished basement, no test yet | People spend hours in that room | Test before you spend anything else on the space |
| Crawl space rather than a slab | Different system design | The membrane becomes part of the system |
| On a private well | Water is a separate pathway from air | Separate test, separate system if needed |
How the job runs
It starts with a number. If you already have a test result, bring it. If you do not, that is where we begin, because there is no sense designing a system for a house nobody has measured.
Then somebody looks at the house. Where the slab is, where the pipe can run, where the fan can sit so you are not listening to it in the room above. That layout is most of the job and it is why we do not quote it over the phone.
On install day the slab gets cored, the pipe goes in and runs out and up, the fan goes on it, and the obvious entry points get sealed so the system is pulling from under the slab rather than out of your basement.
Then we test again. That second test is the point of the whole exercise, and you should insist on it from anybody you hire, us included.
What Nashua’s own records say about water
Nashua does not guess about this, and neither should we. The city keeps its own numbers, and they are worth knowing before you spend money on a basement.
Roughly 20 percent of the city runs on combined sewers, which carry sewage and stormwater in the same pipe, and the city notes that some of those sewers date back to the 1880s (City of Nashua Stormwater Funding Feasibility Study, 2011). The drainage network they are attached to is large: 8,069 catch basins, 130 miles of drainage pipe, 807 outfalls, and about 400 catch basins cleaned a year, which is roughly five percent of them.
The city also names the places that give trouble. Old Maid’s Brook at Shelley Drive and Browning Avenue “currently overtops the road creating a hazard.” Harris Brook at Northeastern Boulevard does the same. Manchester and Charlotte floods “due to a lack of a drainage system” (same study, capital improvement list).
And when it rains hard here, basements are what fills. In the 11 September 2023 event, Nashua Emergency Management recorded about a dozen reports of flooded basements, with 2 to 6 inches of rain reported between Hollis, Nashua and Hudson (City of Nashua Hazard Mitigation Plan Update, 2024).
The ground under the city
Four watersheds sit inside Nashua, all draining to the Merrimack, and the city’s floodplains run with Pennichuck, Hale, Hassel and Salmon Brooks as well as the two rivers (Nashua Natural Resources Inventory and Conservation Plan, 2006). The land falls from Gilboa Hill at 426 feet to about 90 feet at the Merrimack in the southeast corner.
Gilboa Hill is not just high ground. The USGS records it as one of several thick-till-cored drumlins in the area. Till is dense, mixed glacial material, and it drains slowly. Down near the rivers the soils are different again, with Windsor and Hinckley types among the largest mapped units in this survey area (NRCS soil survey NH601).
So a house on Gilboa and a house off Main Dunstable can have genuinely different water behaving genuinely differently, in the same city, in the same storm.
That is the regional picture. It is not a reading of your lot, and we are not going to pretend it is. Two houses on one street can sit on different material. The free inspection is where we find out which one you have.
Flood insurance and the streets that carry water
Nashua joined the National Flood Insurance Program on 15 June 1979, and as of January 2017 held 155 policies in force against $43,548,100 of insurance, with 31 paid losses. The NOAA gauge on the Merrimack at Nashua sets minor flood stage at 18 feet and records a crest of 41.3 feet in March 1936.
Several road crossings sit inside the floodway itself: Main Street at the Nashua River, Allds Street at Salmon Brook, Manchester Street at a floodway crossing, with Pine Hill Road inside the 0.2 percent floodplain. Salmon Brook, which takes in Hassell, Old Maid’s and Hale Brooks over its 6.5 miles, is listed impaired for E. coli with the source recorded as illicit connections to storm sewers.
None of that is a verdict on a specific street. It is the shape of how this city moves water, and it is the background we are working against when we look at a basement here.
What our customers say
Radon assessment went easy, install went easy, experienced and knowledgeable experts, radon levels dropped by next morning to well below EPA action levels. Great work!
Jerome Washo, Google review, 5 stars
That is one of more than 240 Google reviews. We would rather you read them than take our word for anything on this page.
Related pages for Nashua
- Basement waterproofing in Nashua
- Radon mitigation
- How radon testing works
- Every town we cover
- Who you would actually be dealing with
- Basement waterproofing
- Straight answers to basement questions
Book a free inspection in Nashua
Somebody comes out, looks at the actual space, and tells you straight what it needs and what it does not. You get a written number for a defined scope. No two hour pitch, because we would rather be at the next house.
If you are looking for a team that isn’t going to treat you like another number, we would be happy to give you an estimate free of charge. We don’t cut corners. We stand behind our work. We care.
Call 603-610-1770 or book your free inspection. We cover Nashua and the surrounding towns from our shop in East Kingston, New Hampshire.
Common questions about radon
- Can radon levels of 100 be mitigated effectively, and if so how much?
- Did you have radon mitigation done in your home? What things should you know first?
- Do ceiling fans reduce radon?
- Do radon mitigation systems decrease the value of your house?
- Does it matter if I test for radon in the summer or the winter
- How can airflow and HVAC systems affect radon levels throughout a house?
- How can I mitigate radon in an older house with no access to the crawl space?
- How do I test for radon in my basement to make sure the levels are safe?
- How do you get rid of radon gas in a basement?
- How much does a typical radon mitigation system cost?
- How much radon is dangerous if I’m going to live in the basement of a house?
- How quickly do radon levels change?
More 603 services in Nashua
- Basement Waterproofing in Nashua, NH
- Basement Finishing in Nashua, NH
- Crawl Space Encapsulation in Nashua, NH
- Foundation Crack Repair in Nashua, NH
