Crawl space vapor barrier in Missoula MT - the dirt covered and the damp kept below
Musty smell, cold floors or bare damp dirt under the house? We cover the ground and seal the seams so that damp stays down in the soil.
Do I need a vapor barrier in my crawl space?
A crawl space vapor barrier is a heavy plastic sheet laid over the dirt floor under your house. In Missoula homes it keeps ground moisture down in the soil instead of letting it rise into the floor framing and the rooms above.
Most calls I get about crawl spaces start with a musty smell, floors that feel cold all winter or a hatch nobody has opened in years. The price mostly turns on how big the crawl space is, whether you want a plain ground cover or the whole space sealed, and whether water has to be dealt with first. Those same things set the schedule, along with any permit check. After I've been under your house, the written estimate lays out each step and why it's there.
- Licensed and fully insured.
- Free in-person estimates.
- Replies within 1 business day.
Vapor barrier, crawl space and attic work
How we put in a crawl space vapor barrier
I start by crawling the whole space with a flashlight, looking at where water gets in, how the vents are set up and what's down there, like a furnace, ducts or a water heater. If water is coming in, we deal with that first, because plastic laid over a wet problem just hides it, the same way you'd never frame a wall on a rotten sill. Then I walk you through the choice between a plain ground cover and sealing the whole crawl space, which means closing the vents, insulating the walls and sealing the cover to them so the space is kept heated like the rest of your house. Here's where I come down on it. If your furnace or ducts live down there, sealing usually wins, because it keeps humid outside air off that equipment and helps it last, and if the space is just dirt and pipes, a good ground cover is usually all you need. Once the debris is out, we roll out the plastic, overlap and seal the seams, seal it around pipes and run it up the walls and piers, and where someone will be crawling to the furnace, we lay down a tougher path so knees and toolboxes don't wear through it.
A crawl space is only one end of the house. If the walls or a basement need their own moisture layer, our vapor barrier installation work covers that. Up top, attic air sealing closes the gaps around can lights, pipes and the hatch, so warm air stops leaking out the top and pulling damp air up from below.
Why Missoula homeowners call us for crawl space vapor barriers
I crawl every job myself
I come out to look at each crawl space myself, and I work alongside our crew on the install, so the person who quoted the job is the one under your house. I framed houses for years before switching to insulation, and we started our own company in 2023, so I know how your floor framing sits before we open the hatch.
Licensed in Montana, fully insured
Montana requires every construction contractor to be licensed with the state Department of Labor & Industry, so it's fair to ask anyone you call whether they are. We're licensed and fully insured, so you aren't the one carrying the risk while our crew works under your house.
Inside and outside city limits
We're based in Missoula and work in Missoula, Orchard Homes and the cities around them, both inside and outside city limits. Whether your house sits on a city street or out past the limits, you get the same crew and the same order of work.
Under a house, what matters most is fixing the water before the plastic goes down. Call (406) 317-4027 or send us a request with your crawl space's rough size and whether a furnace or water heater sits down there, and I'll come take a look.
Get a written estimate for your crawl space vapor barrier
Send the form and we'll reply within one business day to set a time for me to come look. The on-site estimate is free and comes with no obligation.
- Licensed and fully insured.
- Free in-person estimates.
- Replies within 1 business day.
What happens after you call about your crawl space
Call or send a request
Call (406) 317-4027 or use the form, and we'll set a time for me to come out. If you've got things stored down there, clearing them out before the install lets the plastic cover the ground all the way to the walls.
I crawl it with you
I go through the crawl space with you and answer whatever you want to ask about what we find. Then I send a written estimate that explains each step and why it's there, with the plain cover and the sealed option both priced where both make sense.
We handle what comes first
We take care of anything that has to come first, like a water problem or a permit. Then we lay and seal the cover, or seal the whole space if that's what you chose.
Walk through it together
We clean up and walk the finished crawl space with you, seams, edges and the furnace path included. Your satisfaction, guaranteed.
Crawl space vapor barrier questions from Missoula
Does my crawl space need a vapor barrier if it has vents?
Yes, federal building guidance says the plastic ground cover should go in whether the crawl space is vented or sealed. So you can plan on the cover either way and settle the vent question on its own.
What does a sealed crawl space cost in Missoula?
Sealing a 1,500 sq ft crawl space in Missoula with a vapor barrier and a commercial dehumidifier usually runs about $5,000 to $9,000. That's the going rate around here for full sealing, not our price, and a plain ground cover is a smaller job. The written estimate after I've seen your crawl space gives you the number for your house.
What causes a wet crawl space?
In a vented crawl space, most of the moisture usually comes from water getting in, through ground that slopes toward the house, missing drainage around the foundation or sprinklers soaking the beds next to the wall. That's why a wet crawl space may need grading or drainage work as part of the plan, along with the plastic.
How do I find out if crawl space work needs a permit in Missoula?
Ask the City of Missoula if you're inside city limits, or the Missoula County Building Division if you're outside them. The city's list calls for mechanical permits on added vents, ducts and new heating or cooling equipment, and vapor barriers aren't named on it, so the answer can change with what your job includes. We check with whichever office covers your house, tell you what they said and take care of any permit the work needs before we start.
Is a safety test needed after sealing a crawl space?
Yes, if a natural draft furnace or water heater, one that sends its exhaust up a flue with no fan, sits in the crawl space, a federal checklist for this work calls for a combustion safety test after sealing. The test checks whether exhaust is spilling back from that equipment, so plan on it as part of the job, and I'll note it on the estimate when I see that kind of equipment down there.
Does a crawl space vapor barrier help with radon?
The plastic cover helps keep soil gases from coming up into your house, but it won't tell you what your radon level is, so a test is how you find out. Missoula County sells short-term radon test kits at a discounted price at 301 West Alder Street, or you can call them at 406-258-4755.
Where else we do insulation work
Work that pairs with a crawl space vapor barrier
Vapor barrier installation
When a basement wall or another part of the house needs its own moisture layer, we can plan that alongside the crawl space so the work fits together.
Attic air sealing
If upstairs rooms run cold or the power bill climbs every winter, sealing the attic's leaks is usually the next job after the floor below is done.