Radon Mitigation in Merrimack, NH

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 Merrimack, 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.

Why Merrimack drains the way it does

Merrimack sits on more sand and gravel than most of the towns we cover, and that is measured rather than a feeling.

The town’s own master plan records that stratified drift aquifers underlie approximately 19 square miles, or 57 percent of the Town. Of the SSURGO-mapped acres inside the town line, 40.5 percent is well drained and another 39.5 percent is excessively drained, with Canton fine sandy loam and Windsor loamy sand among the most extensive soil series. The USGS separately found that more than 41 percent of the South Merrimack quadrangle is sand or gravel deposited by glacial meltwater.

Coarse ground moves water fast. The town notes the flip side of that plainly: soils with severe limitations for septic systems cover approximately 70 percent of Merrimack.

Where the water actually goes

Elevations run from several hills over 450 feet in western Merrimack down to under 150 feet along the Merrimack River, over rolling terrain with slopes mostly between 0 and 15 percent. The 100-year floodplain covers about 2,204 acres, and the town’s Hazard Mitigation Plan states that “the Island Drive area of Merrimack is particularly prone to flooding.”

This is not new. The same plan’s historic record includes a March 1977 ice jam on the Souhegan River with the impact recorded as five homes flooded in Merrimack. The USGS gage on the Souhegan at Merrimack drains 171 square miles and has a peak of record of 16,900 cubic feet per second.

Wetlands account for 509 acres, and the town defines wetlands as areas of poorly and very poorly drained soils, protected through its Wetland Conservation District.

What it means for a basement here

Ground that drains quickly is not the same as ground that keeps water away from a foundation. Fast-moving water still has to go somewhere, and a foundation is an obstacle in its path.

Worth knowing about the housing too: Census figures put Merrimack at 11,145 housing units, with 33.3 percent built before 1980 and the largest single cohort built in the 1980s. Foundations of different eras were built to different expectations.

All of that is town-level. None of it tells us what is under your house, and we would not quote a job off it. Somebody comes and looks first.

Where the drinking water comes from, and why it matters

About 85 percent of Merrimack takes its drinking water from wells, and the town’s stratified drift is the productive aquifer. The USGS records saturated thickness of stratified drift across this planning area ranging from under 20 feet near aquifer boundaries to more than 100 feet in the Souhegan and Merrimack valleys.

That is the same material a foundation sits in. Ground that yields water to a well is ground that moves water past a basement wall.

Merrimack holds 95 NFIP policies with $22,316,200 of insurance in force, and has recorded 51 paid losses totalling $1,205,852 along with 8 repetitive loss properties. Repetitive loss is the number worth noting, because it describes properties that flooded, were paid out, and flooded again.

What our customers say

We had a great experience with 603 basement solutions and would highly recommend to anyone looking for a reliable company. Justin and Dillion were the team members who helped with our radon mitigation and they were both extremely knowledgeable, experienced, genuine and prompt. We felt like we were in great, honest hands and the work was completed very quickly. We are appreciative– Thank you!

Jenna Chopak, 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 Merrimack

Book a free inspection in Merrimack

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 Merrimack and the surrounding towns from our shop in East Kingston, New Hampshire.

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