Crawl Space Encapsulation in Lowell, MA

Encapsulation seals a crawl space off from the ground. Liner on the dirt floor, barrier up the walls, the whole thing tied together and sealed, and a way to control the moisture that is already in there. In Lowell it usually runs $3,000 to $25,000, quoted in writing after we look at it.

How do you know your crawl space needs it?

You usually smell it before you see it. That damp, closed-up smell in the room above the crawl is air coming up out of the crawl, because that is what air does in a house. It moves up.

Other things we get called for:

Floors above the crawl that feel cold or springy
Condensation on ductwork or pipes down there
Rot at the bottom of framing, or fungus growing on joists
Mice, red squirrels, anything that found a way in and stayed
A dirt floor that is damp to the touch even in a dry stretch

An unhealthy crawl space will rot your house from the inside out. It is not the kind of thing that holds steady and waits for you.

What actually goes in

A real encapsulation is not a sheet of plastic thrown on the dirt. Ours is a liner across the full floor, barrier run up the foundation walls, everything lapped and sealed so there is no open seam, and moisture control sized for the space. We spec a heavier liner on the floor than on the walls, because the floor is what gets walked on when somebody has to get down there to run a wire in ten years.

If there is standing water, that gets solved first. Sealing a wet crawl just traps the water on the inside of a nice new liner.

What it costs in Lowell

$3,000 to $25,000, and that is a wide range because crawl spaces are wildly different from each other. What moves your number:

Square footage. The single biggest driver.
Headroom and access. A crawl you can sit up in is a different job from one somebody has to army-crawl through with materials.
What is down there now. Old insulation falling out of the joists, debris, a previous half-attempt at a vapor barrier. It all has to come out first.
Whether there is water to deal with. Drainage or a pump adds to it.
Rot. If framing is gone, that is structural work and it happens before the liner.

We give you a written number after somebody has been in the crawl. Not before.

The warranty

Crawl space encapsulation carries a 25 year warranty on the liner, the wall barriers and the workmanship. Dehumidification carries 5 years per the manufacturer terms.

One thing worth knowing: if somebody else later fastens into a sealed wall and puts holes through the barrier, that damage is not covered. Tell whoever works down there next that there is a system on those walls.

Questions we get

Should I just add vents instead?
Venting a crawl space in New England means inviting in humid summer air that then condenses on cool surfaces. Sealing is the approach we use.

Do I need a dehumidifier too?
Usually yes for a full encapsulation, because sealing controls where moisture comes from but does not remove what is already in the air. We size it to the space.

Can I do part of it now?
Yes, and people do. Tell us the whole plan so we do the first part in a way that does not have to be undone.

How long does it take?
Most crawls are a day or two once we start. Rot repair or drainage adds time.

What you are seeing, and what it usually means

What you notice	What it usually points to	What we normally do
Musty smell in the rooms above	Crawl air moving up into the house	Seal the crawl, then control the moisture left in it
Cold or springy floors	Insulation failed, or framing has softened	Check the framing first, insulate after the seal
Condensation on ducts and pipes	Humid air meeting cold surfaces	Dehumidification sized to the space
Damp dirt floor in a dry spell	Ground moisture coming up continuously	Full floor liner, lapped and sealed to the walls
Standing water after rain	Water entering, not just vapour	Drainage or a pump before anything gets sealed
Fungus or soft spots on joists	Rot, which is structural	Repair the framing first. Sealing over rot hides it

How the job runs

Somebody comes out and gets into the crawl. Not a look through the hatch with a torch, actually in there, because you cannot see the far corners from the opening and the far corners are usually where the trouble is.

Then you get a written scope. What is coming out, what is going in, what it costs. If there is rot or standing water, that is its own line and its own sequence, because sealing over either one just hides it under a new liner.

On the day, the old material comes out first. Debris, fallen insulation, whatever the last owner left. The liner goes down across the full floor, runs up the walls, and every seam gets lapped and sealed. Then the moisture control goes in and gets set.

Most crawls are a day or two. Rot repair or drainage adds to that, and we will tell you which one you are before we start rather than after.

Lowell has been managing water since 1941

Lowell sits where the Concord River meets the Merrimack, and the city has spent most of a century dealing with what that means.

The Flood Damage Reduction system was originally constructed in 1941 by the Army Corps of Engineers, built in response to the devastating floods of 1936 and 1938 (City of Lowell). The Merrimack’s flood stage at Lowell is 52 feet, with action at 50, moderate at 54 and major at 58.

The city currently has 9 combined sewer overflow outfalls contributing 330 million gallons of combined sewer to the Merrimack, the Concord and Beaver Brook (Lowell Regional Wastewater Utility).

Where Lowell floods, by the city’s own record

Lowell’s Hazard Mitigation Plan names the places. The Beaver Brook dam area is recorded as “the most common area of flooding.” Townsend Avenue near Pawtucketville, next to Clay Pit Brook, is another. Beaver Brook, Black Brook, Clay Pit Brook and Scarlet Brook are all named perennial streams in the city.

The repetitive-loss figures are the ones worth sitting with: 25 repetitive-loss buildings, 55 losses, $584,907 in repetitive-loss payments, and 245 closed paid claims totalling $4,942,173. Those are properties that have flooded more than once and been paid out more than once.

The layer under your slab

Here is the part that actually explains a lot of wet Lowell basements. The major soil components mapped across the city carry a densic restrictive layer, and the depths are recorded: Paxton at 66 to 71 centimetres, Woodbridge at 76 to 81, Montauk at 87 to 92 (USDA NRCS Soil Data Access, clipped to the Lowell city polygon).

A densic layer is compacted glacial till that water does not readily pass through. Water moving down through the soil reaches it and has to go sideways instead. Where a foundation is in the way of sideways, you get a wet basement, and no amount of sealing the inside of the wall changes where the water is going.

The city’s elevation runs from about 39.5 feet to 313.6 feet, so how that plays out varies a great deal across town.

That is the mapped picture for Lowell as a whole. What is under your house on your street is established by looking, and the look is free.

The rivers, and the gauges that watch them

The Concord River gauge at Lowell sets action stage at 7.5 feet, minor at 8, moderate at 10 and major at 12, with a record crest of 9.74 feet and 5,840 cubic feet per second on 17 March 2010. That March 2010 event appears in the city’s own storm-event record.

Lowell has also put money behind one of its problem watersheds: a $138,000 state Municipal Vulnerability Preparedness grant in FY21 for the Claypit Brook watershed on the northwestern side of the city.

On geological hazards the city is direct. Its plan states that officials “did not identify any local areas that were previously recorded as being vulnerable to geologic hazards,” and classifies all of Lowell the same way for that risk. So the water story here is a surface-water and soil story, not a bedrock-instability one.

What our customers say

From our initial meeting with Rich to project close out with Nik 603Basement did not disappoint! We have a 12-18 inch crawl space under our house. Toni, Erik, Chris and Angel worked tirelessly in that tight space for over a week to clean out old debris, run a sump pump, humidifier, vapor barrier and spray foam to dry out the space and preserve our home. The sump worked overtime to keep our space dry during the torrential Christmas downpour. We cannot say enough about this team’s customer service and project commitment! Thanks 603B we will be calling you for future projects and referring friends. Ian and Shawna Evans

Shawna Evans, 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 Lowell

Book a free inspection in Lowell

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

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